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A large biodiversity of “skeneimorph” (Gastropoda:
Vetigastropoda) species from the South Azorean Seamount
Chain, with the description of seventeen new species
Una extensa biodiversidad de especies de “skeneimorfos”
(Gastropoda: Vetigastropoda) de la cadena de montañas submarinas
del Sur de las Azores, con la descripción de diecisiete especies nuevas
Leon HOFFMAN*, 1, Serge GOFAS** & André FREIWALD*
Recibido el 4-III-2020. Aceptado el 18-V-2020
ABSTRACT
Forty-six “skeneimorph” species from the South Azorean Seamount Chain (SASC) have been
studied. These comprise taxa in the superfamilies Trochoidea (family Skeneidae) and Seguen-
zioidea (families Trochaclididae, Pendromidae, Eudaroniidae and several genera which are
not assigned to a family). Seventeen new species are proposed, fifteen in Seguenzioidea
(Trochaclis fortis n. sp., Trochaclis carinata n. sp., Trochaclis platoensis n. sp., Adeuomphalus
axistriatus n. sp., Adeuomphalus curvistriatus n. sp., Eudaronia spirata n. sp., Eudaronia
mikra n. sp., Anekes anderswareni n. sp., Anekes mikrosculpta n. sp., Anekes umbilisculpta
n. sp., Anekes varisculpta n. sp., Moelleriopsis atlantis n. sp., Moelleriopsis gritta n. sp.,
Moelleriopsis meteorminora n. sp., and Trenchia teriuga n. sp.) and two in Trochoidea (Mikro
perforata n. sp., and Skenea basicarinata n. sp.). Three species are transferred to different
genera: Xyloskenea xenos Hoffman, van Heugten & Lavaleye, 2010 is assigned to Trenchia,
Trochus (Margarita) minima Seguenza, 1876 and Lissotesta scalaroides Rubio & Rolán, 2013
to Mikro. Twelve species (26%) are only known from the SASC and are probably endemic
to this region. Twenty-one species are known from the SASC and/or the Azores seamounts
and this set is probably endemic to this larger area. Five amphiatlantic species were found
(11% of total species): Ganesa nitidiuscula Jeffreys, 1883, Rugulina fragilis (G.O. Sars,
1878), Trochaclis islandica Warén, 1989, Xyloskenea naticiformis Jeffreys, 1883 and Xyloske-
nea translucens (Dall, 1927). About 50% of the skeneimorph species found on the SASC are
known from an extensive distribution area in the NE Atlantic and only few of them also live
in the Mediterranean Sea. As usual on seamounts, the number of live-taken specimens is very
low compared to empty shells of the thanatocenosis.
RESUMEN
Se han estudiado cuarenta y seis especies de “skeneimorfos” de la cadena de montañas
submarinas del Sur de las Azores (SASC). Entre ellos hay taxones en las superfamilias Tro-
choidea (familia Skeneidae) y Seguenzioidea (familias Trochaclididae, Pendromidae, Euda-
roniidae y varios géneros sin asignar a una familias). Se proponen diecisiete especies nue-
vas, quince en Seguenzioidea (Trochaclis fortis n. sp., Trochaclis carinata n. sp., Trochaclis
platoensis n. sp., Adeuomphalus axistriatus n. sp., Adeuomphalus curvistriatus n. sp., Euda-
* Marine Research Department, Senckenberg am Meer, Südstrand 40, Wilhelmshaven, Germany
** Departamento de Biología Animal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
1Corresponding author: leon.hoffman@senckenberg.de
© Sociedad Española de Malacología Iberus, 38 (Suplemento 9): 1-82, 2020
1
ronia spirata n. sp., Eudaronia mikra n. sp., Anekes anderswareni n. sp., Anekes mikros-
culpta n. sp., Anekes umbilisculpta n. sp., Anekes varisculpta n. sp., Moelleriopsis atlantis
n. sp., Moelleriopsis gritta n. sp., Moelleriopsis meteorminora n. sp. y Trenchia teriuga n.
sp.) y dos en Trochoidea (Mikro perforata n. sp. y Skenea basicarinata n. sp.). Se transfie-
ren tres especies a diferentes géneros: Xyloskenea xenos Hoffman, van Heugten & Lavaleye,
2010 se asigna a Trenchia, Trochus (Margarita) minima Seguenza, 1876 y Lissotesta
scalaroides Rubio & Rolán, 2013 a Mikro. Doce especies (26%) solo se conocen de la SASC
y son probablemente endémicos de esta región. Se conocen 21 especies de la SASC y/o
los montes submarinos de las Azores y este conjunto es probablemente endémico de este
área más grande. Se encontraron cinco especies anfatlánticas (11% del total de especies):
Ganesa nitidiuscula Jeffreys, 1883, Rugulina fragilis (G.O. Sars, 1878), Trochaclis islandica
Warén, 1989, Xyloskenea naticiformis Jeffreys, 1883 y Xyloskenea translucens (Dall, 1927).
El 50% de las especies de skeneimorfos que se encuentran en el SASC se conocen de una
amplia área de distribución en el Atlántico nororiental y pocas de ellas viven también en el
mar Mediterráneo. Como es habitual en montañas submarinas, el número de ejemplares
recolectados vivos es bajísimo comparado con el de conchas en la tanatocenosis.
KEY WORDS: Mollusca, Trochoidea, Skeneidae, Seguenzioidea, Pendromidae, Trochaclididae, Eudaroniidae,
North Atlantic, endemic species, taxonomy.
PALABRAS CLAVE: Moluscos, Trochoidea, Skeneidae, Seguenzioidea, Pendromidae, Trochaclididae, Euda-
roniidae, Atlántico norte, especies endémicas, taxonomía.
This paper is the fourth in a series of
studies on molluscan groups in the
SASC; previous papers discussed
Seguenziidae (H
OFFMAN ET AL
., 2020a),
the genus Papuliscala in Epitoniidae
(H
OFFMAN ET AL
., 2020b) and Callios-
tomatidae (G
OFAS
& H
OFFMAN
, 2020).
H
OFFMAN ET AL
. (2020a) discussed the
oceanographic aspects of the SASC
seamounts, an overview of previous
publications on Mollusca and the
methodology.
The family name Skeneidae has been
traditionally used as a “purgatory” for
minute, unpigmented, trochiform to
planispiral shells that lack nacre and
range from smooth to elaborately sculp-
tured, awaiting their classificatory fates
through anatomical and molecular
studies (H
ICKMAN
, 2013). To acknowl-
edge this situation, authors tended to
use the informal name “skeneimorph”
(W
ARÉN
, 1992; K
ANO
, 2008) or
“skeneiform” (H
ICKMAN
, 1998) for such
microgastropods sharing the characters
described above, whereas Skeneidae is
restricted for such species being closely
Iberus, 38 (Suplemento 9), 2020
2
INTRODUCTION
This paper reviews skeneimorph
species in the super families Trochoidea
and Seguenzioidea that were encoun-
tered in sediment samples gathered
during three cruises to seamounts in the
South Azorean Seamount Chain (SASC).
The SASC is located about 500 km south
of the Azores and about 1500 km west of
the NW African coastline (Fig. 1A). All
SASC and Azorean seamounts are of
volcanic origin with a summit bathy-
metric range between 200 and 500 m.
These submarine structures have a
rugged outline and most of them are
surrounded by a steep slope reaching
depths exceeding 1000 m.
The SEAMOUNT-2 cruise (G
OFAS
1993) visited the Atlantis, Tyro, Plato,
Irving, Hyères, and Great Meteor
seamounts (Fig. 1B). The POS397 cruise
(G
EORGE
2010) explored the summit
plateau of the Great Meteor Seamount.
The M151 cruise (F
RANK
2018)
appraised various seamounts South of
the Azores, and Atlantis, Great Meteor
and Little Meteor seamounts in the
SASC (Fig. 1B).
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
3
Figure 1. Location maps. A: overview of the NE Atlantic showing the South Azorean Seamount Chain
(SASC), the Azores and Lusitanian seamount group; B: seamounts in the SASC and near the Azores,
the stations from three cruises used in this study are shown; C: the Lusitanian seamount group with
key seamounts indicated. Bathymetric data from GEBCO, depth contours 1000 m.
Figura 1. Mapas de ubicación. A: vista general del Atlántico NE mostrando la cadena de montañas sub-
marinas del Sur de las Azores (SASC), las Azores y el grupo de montañas submarinas lusitánicas; B:
montañas submarinas en la SASC y cerca de las Azores, se muestran las estaciones de las tres campañas
utilizadas en este estudio; C: el grupo de montañas submarinas lusitánicas con indicación de las princi-
pales. Datos batimétricos de GEBCO, isobatas de 1000 m.
A
BC
related to the type genus Skenea
(H
ICKMAN
, 2013; H
ASZPRUNAR ET AL
.,
2016).
Many of the species historically
assigned to Skeneidae or Trochidae
(within Trochoidea) have not only been
excluded from this family but even
moved to other vetigastropod super-
families, like Seguenzioidea (K
ANO
,
2008; K
UNZE ET AL
., 2008, 2016; K
ANO ET
AL
., 2009) or other non-vetigastropod
clades, like Neomphalina (H
Eß ET AL
.,
2008; K
UNZE ET AL
., 2008), or families in
the subclass Heterobranchia (K
UNZE ET
AL
., 2008; H
ASZPRUNAR ET AL
., 2011).
Skeneimorph gastropods are widely
distributed on the bathyal slopes and
plateaus in the NE Atlantic (W
ARÉN
,
1992; H
OFFMAN ET AL
., 2010, 2018). Both
historical and recent papers are impor-
tant contributions on skeneimorph taxa
from the NE Atlantic. J
EFFREYS
(1883,
1884) reported on the Mollusca pro-
cured during the ‘Lightning’ and ‘Por-
cupine’ expeditions and introduced the
genus Ganesa Jeffreys, 1884 and several
new species. D
AUTZENBERG
& F
ISCHER
(1896, 1897) described the Mollusca col-
lected by R.V. Princess Alice, many of
them endemic species from around the
Azores. B
OUCHET
& W
ARÉN
(1979) and
W
ARÉN
(1989, 1991, 1992, 1996) intro-
duced the family Pendromidae Warén,
1991, the genera Anekes Bouchet &
Warén 1979, Akritogyra Warén 1992, Reti-
gyra Warén 1996, and Mikro Warén 1996
and many new species. Likewise W
ARÉN
(1992) provided the most important
review on skeneimorph species in the
NE Atlantic and the Mediterranean Sea.
M
ARSHALL
(1988, 1995) reviewed
skeneimorphs from the SW Pacific
Ocean and introduced the genus
Xyloskenea Marshall, 1988 and also
many new species. More recently,
H
OFFMAN ET AL
.(2008, 2010, 2018) intro-
duced the genus Lopheliella Hoffman,
van Heugten & Lavaleye, 2008 and
described several new species. K
ANO
,
C
HIKYU
& W
ARÉN
(2009) reviewed the
genus Adeuomphalus Seguenza, 1876,
and R
UBIO ET AL
.(2011, 2015, 2019) and
R
UBIO
& R
OLÁN
(2013) reviewed many
skeneimorphs, including the genus
Parviturbo Pilsbry & McGinty, 1945.
R
UBIO ET AL
.(2019), introduced the
genus Seamountiella Rubio, Gofas &
Rolán, 2019 and described several new
species.
MATERIAL AND METHODS
This paper combines material from
the cruises S
EAMOUNT
2 (G
OFAS
, 1993),
POS397 (G
EORGE
, 2010) and M151
(F
RANK
, 2018). All raw material from
POS397 and M151 were sediment
samples stored at SaM. The material
from the S
EAMOUNT
2 cruise were pre-
sorted samples obtained by dredges,
which were stored in the MNHN. The
POS397 material was sorted from sedi-
ment samples obtained by Shipek grabs.
Molluscan remains from M151 were
sorted from sediment samples taken by
ROV manipulator, van Veen grabs and
box cores. Very few specimens were col-
lected alive during these cruises; most
observations were based on empty
shells.
The shells were sorted to species
level using a stereo microscope. Selected
specimens for each species were pho-
tographed using a Scanning Electron
Microscope (SEM, Vega3 – Tescan at
SaM). The specimens were mounted on
SEM stubs and were coated with gold.
Previous attempts failed to obtain high
quality images of shells without gold
coating using low voltage and low
vacuum. SEM imaging was carried out
by secondary electron (SE) imaging
using an incident electron energy of 10
keV. Occasionally, back-scatter electron
(BSE) imaging was used when too much
sample charging was experienced in SE
imaging. Line drawings were addition-
ally made for the new species.
All holotypes and most paratypes
were deposited in MNHN. Their images
and associated location data will be
made accessible at the MNHN home-
page. Few paratypes were stored in
SMF. The remaining material from the
S
EAMOUNT
2 cruise was deposited in
MNHN. The remaining material from
the POS397 and M151 was stored in the
Iberus, 38 (Suplemento 9), 2020
4
reference collection at SaM. Albeit not
mandatory, ZooBank registrations were
made for all the new taxa described in
this paper.
A species distribution has been
inferred for all skeneimorph species
encountered during the three cruises of
this study as well as for species reported
by B
ECK ET AL
. (2006) from the Seine,
Ampère and Gettysburg seamounts and
by H
OFFMAN
& F
REIWALD
(2017) from
the Coral Patch Seamount (Fig. 1C).
Species in this list are compared with lit-
erature records from the NE and NW
Atlantic.
Coordinates in degrees and minutes
from original station lists were con-
verted to decimal degrees, which are
standard for use in Geographic Informa-
tion Systems (GIS).
Abbreviations:
Institutions: MNHN - Muséum National
d’Histoire Naturelle; SMF – Senck-
enberg Museum Frankfurt; SaM –
Senckenberg am Meer; SaMID – col-
lection identification number at
SaM.
Cruises: M151 – R/V Meteor Cruise 151;
POS397 – R/V Poseidon cruise 397;
R/V – research vessel; SMT2 – R/V
Suroit cruise SEAMOUNT2.
Morphology: H – height; W – width,
diameter in apertural view.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
5
SYSTEMATIC RESULTS
M
OLLUSCA
, G
ASTROPODA
, V
ETIGASTROPODA
Superfamily S
EGUENZIOIDEA
Verrill, 1884
We have included species belonging
to Pendromidae, Trochaclididae and Eudaroniidae, and others without
family allocation.
Family P
ENDROMIDAE
Warén, 1991
Genus Rugulina Palazzi, 1988
Type species: Daronia monterosatoi van Aartsen & Bogi, 1987 by original designation, Mediter-
ranean Sea.
Shells of Rugulina are fragile
depressed with wide open umbilicus,
and spiral cordlets. Aperture is strongly
prosocline, sharp, elongated.
Six species are currently known in the
genus; three from the Antarctic and three
from the northern hemisphere: Rugulina
monterosatoi (van Aartsen & Bogi, 1987)
from the Mediterranean Sea, R. fragilis
(G.O. Sars, 1878) from the northeastern
Atlantic and R. verrilli (Tryon, 1888) from
the northwestern Atlantic.
Rugulina fragilis (G.O. Sars, 1878) (Fig. 2)
Adeorbis fragilis G.O. Sars 1878: 213, tab. 22, fig. 19a-c.
Rugulina fragilis: W
ARÉN
, 1991: 72-73, figs. 11A-E; 13A-B.
Material examined: Azores, Mar da Prata • 4 shells; 37.601°N, 25.874°W; 190 m; 16 Oct. 2018;
M151/23160; grab. • 6 shells; 37.659°N, 25.789°W; 599 m; 19 Oct. 2018; M151/23181; box core. Atlan-
tis Seamount • 2 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. • 1 shell;
33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Plato Seamount • 5 shells; 33.210°N,
29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
Distribution: Greenland, Iceland,
Norway (W
ARÉN
, 1991), Rockall Bank,
Porcupine Basin (F
REIWALD
& B
ECK
,
2007, H
OFFMAN ET AL
., 2010), Seine
Seamount (B
ECK ET AL
., 2006), Canaries
(O
RTEGA
& G
OFAS
, 2019), Azores and
SASC (this study), 150–1500 m.
Remarks: The species has a yellowish
shell with spiral cords and a chaotic sculp-
ture on the upper part of the whorls.
Iberus, 38 (Suplemento 9), 2020
6
Figure 2. Rugulina fragilis (G.O. Sars, 1878). A: Plato Seamount – SMT2/DW250, H 2.6 mm, W
2.5 mm; B, C: protoconch W 0.21 mm.
Figura 2. Rugulina fragilis (G.O. Sars, 1878). A: Banco Plato - SMT2/DW250, 2,6 mm alto, 2,5
mm ancho; B, C: protoconcha 0,21 mm ancho.
A
BC
Family T
ROCHACLIDIDAE
Thiele, 1928
Genus Trochaclis Thiele, 1912
Type taxon: Trochaclis antarctica Thiele, 1912 by monotypy, Antarctic.
W
ARÉN
(1992) provided a diagnosis
for the shell in the genus: small, tall-spired
shell with smooth sculpture except for two
to four, strong, steeply ascending spiral
cords in the umbilicus. Protoconch spi-
rally aligned hexagonal cells.
Twelve species are currently known in
the genus, eight of them extant of which
five extant and two fossils were described
by M
ARSHALL
(1995) from New Zealand.
The species from New Zealand show a
wide morphological variability. Two
species are known in the Atlantic and
Mediterranean Sea: Trochaclis islandica
Warén, 1996 and T. versiliensis Warén, Car-
rozza & Rocchini in W
ARÉN
(1992).
Trochaclis islandica Warén, 1989 (Fig. 3)
Trochaclis islandica Warén, 1989: 9-11, figs. 6-7.
Material examined: Plato Seamount • 1 shell; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge.
Distribution: known from Green-
land, Iceland, Norway, off Ireland
(W
ARÉN
, 1989), SASC (this study),
150–1500 m.
Remarks: The species can be identi-
fied by three cords in the umbilical area;
it lacks a supraperipheral cord on the
first whorl of the teleoconch.
100 µm
100 µm
Trochaclis versiliensis Warén, Carrozza & Rocchini in Warén, 1992 (Fig. 4)
Trochaclis versiliensis Warén, Carrozza & Rocchini in Warén, 1992: 180, figs. 26E, 36A-D;
H
OFFMAN ET AL
. 2018: 30-31, figs. 21-24.
Material examined: Azores, Mar da Prata • 4 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. • 3 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab. • 1 shell;
37.666°N, 25.966°W; 952 m; 17 Oct. 2018; M151/23168; grab. • 5 shells; 37.659°N, 25.789°W; 599 m;
19 Oct. 2018; M151/23181; box core. Atlantis Seamount • 4 shells; 34.412°N, 30.513°W; 795–830 m;
03 Feb. 1993; SMT2/DW264; dredge. • 3 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404;
grab. • 3 shells; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Tyro Seamount • 1
live-collected specimen, 3 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278;
dredge. Great Meteor Seamount • 2 shells; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-
R6; ROV sample. • 4 shells; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample.
• 1 shell; 30.086°N, 28.726°W; 906 m; 26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Sea-
mount • 2 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
7
Figure 3. Trochaclis islandica Warén, 1989. A-C: Plato Seamount – SMT2/DW250, H 2.9 mm, W
3.0 mm; D: protoconch W 0.34 mm.
Figura 3. Trochaclis islandica Warén, 1989. A-C: Banco Plato – SMT2/DW250, 2,9 mm alto, 3,0
mm ancho; D: protoconcha 0,34 mm ancho. Barras de escala 100 m.
Distribution: Rockall Bank, Porcu-
pine Basin, the Lusitanian seamounts off
NW Morocco, off Portugal, NW Spain
(W
ARÉN
, 1992, H
OFFMAN ET AL
. 2018),
SASC, Azores (this study) and the
western Mediterranean (W
ARÉN
1992),
200–1000 m.
Remarks: The species can be identi-
fied by the two strong and rough cords
in the umbilical area, and a characteris-
tic cord on the first teleoconch whorl.
The latter feature is occasionally weak
or absent. T. islandica is more raised and
has three umbilical cords.
A
BC
D100 µm
Trochaclis fortis n. sp. (Figs. 5, 6)
Type material: Holotype, Little Meteor Seamount • 1 shell (Figs. 5A-D); 29.655°N, 29.004°W; 464 m;
27 Oct. 2018; M151/23438; grab, in coarse bioclastic sand with coral rubble; MNHN-IM-2000-35648.
Type locality: Little Meteor Seamount, 29.655°N – 29.004°W, 464 m.
Etymology: fortis (Latin) refers to the strong appearance of the shell.
surface flattened above cord, convex
below, numerous fine prosocline growth
lines. Second whorl convex, spiral cord
faded out, whorl descending with upper
suture below periphery, whorl surface
smooth (with round predation hole dor-
sally). Third (body) whorl smooth with
several prosocline growth markings,
suture shallow, smeared.
Base of body whorl with a weak keel
de marcating umbilical area and a thick
and steep cord at the outer edge of
umbilicus. Umbilicus very narrow, cres-
cent-shaped.
Aperture 50% of shell height, oblong,
slightly angular at union with penultimate
Iberus, 38 (Suplemento 9), 2020
8
Figure 4. Trochaclis versiliensis Warén, Carrozza & Rocchini, 1992. A, B: Atlantis Seamount –
M151/23404, H 1.9 mm, W 2.0 mm; C: protoconch W 0.25 mm, same as A-B; D, E: Little Meteor
Seamount – M151/23438, H 1.2 mm, W 1.2 mm; F: protoconch W 0.23 mm, same as D-E.
Figura 4. Trochaclis versiliensisWarén, Carrozza & Rocchini, 1992. A-B: Banco Atlantis – M151/23404,
1,9 mm alto, 2,0 mm ancho; C: protoconcha 0,25 mm ancho, misma que A-B; D, E: Pequeño Banco
Meteor – M151/23438, 1,2 mm alto, 1,2 mm ancho; F: protoconcha 0,23 mm ancho, misma que D-E.
Holotype, an empty shell (Figs. 6A-D):
Small (H 1.7 mm, W 1.4 mm) and solid
shell with a flattened apex, cyrtoconoid
outline, spire apical angle about 52°,
with umbilical cord on the base, white.
Protoconch: ¾ whorls, spirally
aligned flat pits with flattened walls, flex-
uous sharp lip, somewhat flaring, fol-
lowed by a straight thick varix forming a
rounded rim and with a tapering edge
towards teleoconch, W 0.25 mm. Transi-
tion to teleoconch clear by varix and
change in sculpture (Figs. 5B, 6D).
Teleoconch: Three rounded whorls,
suture very shallow. First whorl with
smooth spiral cord forming a weak keel,
A
B
C
DEF
100 µm
100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
9
Figure 5. Trochaclis fortis n. sp. A: Little Meteor Seamount – M151/23438, holotype, apertural
view, H 1.7 mm; B: apical view of protoconch showing sculpture with spirally aligned pits, a flexu-
ous lip followed by a varix, W 0.25 mm.
Figura 5. Trochaclis fortis n. sp. A: Pequeño Banco Meteor - M151/23438, holotipo, vista apertural,
1,7 mm alto; B: vista apical de la protoconcha mostrando la escultura con hoyos alineados en espiral, un
borde flexuoso seguido de una variz, 0,25 mm ancho.
Figure 6. Trochaclis fortis n. sp. A-C: Little Meteor Seamount – M151/23438, holotype, H 1.7
mm, W 1.4 mm. D: protoconch W 0.25 mm.
Figura 6. Trochaclis fortis n. sp. A-C: Pequeño Banco Meteor – M151/23438, holotipo, 1,7 mm alto,
1,4 mm ancho. D: protoconcha 0,25 mm ancho.
500 µm
100 µm
A
B
A
BC
D100 µm
whorl. Peristome flexuous at base, thick,
outer lip bevelled to a sharp edge, proso-
cline at 30° with spire axis. Columella and
parietal lip smooth, thick and curved,
inside of whorl smooth. Angle of union
with penultimate whorl about 80°.
Variability: Unknown.
Distribution: Only known from the
type locality.
Remarks: The species is placed in the
genus Trochaclis based on the proto-
conch and the umbilical sculpture. It is
very similar to Trochaclis versiliensis but
this species is less raised and it has an
open umbilicus with two strong cords
(Figs. 4A,B,D,E). It is also similar to
Trochaclis atypica (Laws, 1939) and
Trochaclis bucina (Laws, 1941), both from
the Miocene of New Zealand; these
species are adapically more raised and
their whorls are more flattened (M
AR
-
SHALL
, 1995).
Iberus, 38 (Suplemento 9), 2020
10
Figure 7. Trochaclis carinata n. sp. Plato Seamount – SMT2/DW250, holotype, apertural view, H
1.8 mm; B: apical view of protoconch showing sculpture with spirally aligned pits, a flexuous lip
followed by a varix, W 0.31 mm.
Figura 7. Trochaclis carinata n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apertural, 1,8
mm alto; B: vista apical de la protoconcha mostrando la escultura con hoyos alineados en espiral, un
borde flexuoso seguido de una variz, 0,31 mm ancho.
Trochaclis carinata n. sp. (Figs. 7, 8)
Type material: Holotype, Plato Seamount. •1 shell (Figs. 6A-D); 33.210°N, 29.287°W; 1450–1500 m;
01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments;MNHN-IM-2000-35649.
Type locality: Plato Seamount, 33.210°N – 29.287°W, 1450–1500 m.
Etymology: carinata (Latin) refers to the weak keels on the body whorl.
Holotype, an empty shell (Figs. 8A-D):
Small (H 1.8 mm, W 2.0 mm) and solid
shell, with a regularly raised spire, with
weakly angular whorls, apical angle
about 100°, with strong umbilical cords
on the base, white.
Protoconch: ¾ whorls, spirally
aligned network of flat pits on the
nucleus, smooth towards the convex lip,
thick rounded smooth varix, W 0.31
mm. Transition to teleoconch clear by
varix and change in sculpture (Fig. 8D).
Teleoconch: 2 ¼ smooth rounded
whorls, numerous fine, prosocline
growth lines, spiral supraperipheral
cord with weak keel decreasing in
strength, faded on body whorl. Surface
flattened above cord, convex below.
Suture very shallow, sloping, union at
about 80° to previous whorl. A second
weak cord above suture.
Base of body whorl with eight strong
spiral cords below periphery, smooth and
rounded, spaced irregularly with flattened
500 µm
100 µm
A
B
interspaces. Upper basal cord starting
below end of suture, forming weak keel.
Fourth basal cord forming another weak
keel demarcating umbilical area. Four
strong cords on umbilical area; last cord
with strong keel at edge of umbilicus.
Umbilicus narrow, deep, tortuous.
Aperture 60% of shell height,
rounded, angular at union with penulti-
mate whorl. Outer lip sharp, bevelled to
a cutting edge, thick, prosocline at 30°
with spire axis. Columella curved. Col-
umellar callus thick, smooth; parietal
callus thin, smooth; inside of whorl
smooth. Angle of union with penulti-
mate whorl sloping at about 75°.
Variability: unknown.
Distribution: only known from the
type locality.
Remarks: The species is placed in the
genus Trochaclis based on the protoconch
and umbilical sculpture. It is similar to
Trochaclis versiliensis as it shares the adapi-
cal cord on the upper whorl surface,
however, this species has only two strong
basal cords (Figs. 4A, B, D, E).
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
11
Figure 8. Trochaclis carinata n. sp. A-C: Plato Seamount – SMT2/DW250, holotype, H 1.8 mm,
W 2.0 mm; D: protoconch W 0.31 mm.
Figura 8. Trochaclis carinata n. sp. A-C: Banco Plato – SMT2/DW250, holotipo, 1,8 mm alto, 2,0
mm ancho; D: protoconcha 0,31 mm ancho.
Trochaclis platoensis n. sp. (Figs. 9, 10)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 10A-D); 33.210°N, 29.287°W; 1450–1500 m;
01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-
35650. Paratypes: • 3 shells (Figs. 10E-O); same data as for holotype; MNHN-IM-2000-35651. • 3
shells; same data as for holotype; MNHN-IM-2000-35652.
Type locality: Plato Seamount, 33.210°N – 29.287°W, 1450–1500 m.
Etymology: platoensis (Latin) refers to the type locality, the Plato Seamount.
ABC
D100 µm
Holotype, an empty shell (Figs. 10A-D):
Small (H 1.9 mm, W 2.3 mm) and mod-
erately solid shell with a regularly
raised apex with well-rounded whorls,
spire apical angle about 110°, sculpture
of strong spiral cords on rough whorl
surface, white.
Protoconch: ¾ whorls, spirally
aligned network of flat pits on the
nucleus, smooth towards the lip, convex
lip, thick rounded smooth varix, W 0.33
mm. Transition to teleoconch clear by
varix and change in sculpture (Fig. 10D).
Teleoconch: Two whorls, numerous
coarse, irregular prosocline growth
lines, micro-sculpture of minute gran-
ules and spiral line segments. On first
whorl, initially one supraperipheral
cord; second cord emerges at ¼ whorl
below first cord, a third cord above at ½
whorl, increasing to eight cords at start
of second (body) whorl. On body whorl,
top cord at some distance from suture,
remaining cords at irregular distances.
Suture shallow, impressed, union at
about 90° to previous whorl.
Base of body whorl with nine strong
spiral cords, smooth and rounded,
spaced regularly with rough inter-
spaces, last cord forming a strong keel
delimiting umbilicus. Base cords
stronger than cords on upper whorl
surface. Umbilicus open, deep, with
rough growth lines inside.
Iberus, 38 (Suplemento 9), 2020
12
Figure 9. Trochaclis platoensis n. sp. A: Plato Seamount – SMT2/DW250, holotype, apertural view,
H 1.9 mm; B: apical view of protoconch showing sculpture with spirally aligned pits, a flexuous
lip followed by a varix, W 0.33 mm.
Figura 9. Trochaclis platoensis n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apertural, 1,9
mm alto; B: vista apical de la protoconcha mostrando la escultura con hoyos alineados en espiral, un
borde flexuoso seguido de una variz, 0,33 mm ancho.
(Right page) Figure 10. Trochaclis platoensis n. sp. A, B: Plato Seamount – SMT2/DW250, holotype,
H 1.9 mm, W 2.3 mm; C: microsculpture on periphery of body whorl of the holotype; D: proto-
conch of the holotype W 0.33 mm; E: paratype 1, W 1.4 mm; F: microsculpture on top of body
whorl, same as E; G: protoconch W 0.33 mm, same as E; H-J: paratype 2, H 1.9 mm, W 2.3 mm;
K: microsculpture on base of body whorl, same as J; L: protoconch W 0.33 mm, same as J; M, N:
paratype 3, H 1.7 mm, W 2.0 mm; O: protoconch W 0.32 mm, same as N.
(Página derecha) Figura 10. Trochaclis platoensis n. sp. A, B: Banco Plato - SMT2/DW250, holotipo,
1,9 mm alto, 2,3 mm ancho; C: microescultura en periferia de última vuelta del holotipo; D: protocon-
cha del holotipo 0,33 mm ancho; E: paratipo 1, 1,4 mm ancho; F: microescultura en parte superior de
última vuelta, misma que E; G: protoconcha 0,33 mm ancho, misma que E; H-J: paratipo 2, 1,9 mm
alto, 2,3 mm ancho; K: microescultura en base de última vuelta, misma que J; L: protoconcha 0,33 mm
ancho, misma que J; M, N: paratipo 3, 1,7 mm alto, 2,0 mm ancho; O: protoconcha 0,32 mm ancho,
misma que N.
500 µm
100 µm
A
B
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
13
AB
C
DEF
H
IG
JKL
M
NO
100 µm
100 µm 100 µm
100 µm
100 µm 100 µm
100 µm
Aperture 70% of shell height, D-
shaped, with sharp outer lip, angular at
union with penultimate whorl and at base
of columella. Outer lip prosocline at 30°
with spire axis. Columellar lip sharp,
slightly curved, callus smooth; parietal
callus thin, smooth; inside of whorl
smooth. Suture deeply impres sed.
Variability: little variability, in type
material 16–19 spiral cords on body
whorl, protoconch width 0.32-0.33 mm.
Distribution: only known from the
type locality.
Remarks: This species is placed in the
genus Trochaclis based on the sculpture
of the protoconch and the smooth,
rounded spiral cords. It is similar to
Trochaclis carinata n. sp. as it shares the
spiral cords on the whorl surface,
however, T. platoensis n. sp. has more
cords without keels and a rough whorl
surface. It is likely that this species
belongs to a different, undescribed
genus but we prefer to retain the species
in Trochaclis without the availability of
soft parts or molecular analysis.
Iberus, 38 (Suplemento 9), 2020
14
Family E
UDARONIIDAE
Gründel, 2004
Genus Eudaronia Cotton, 1945
Type taxon: Cyclostrema jaffaensis Verco, 1909 by subsequent designation, off southern Australia.
The latest classification places this
genus in Seguenzioidea (K
ANO ET AL
.
2009; B
OUCHET ET AL
., 2017). Shells in
the genus are small, up to 3 mm in
diameter, colourless, almost perfectly
planispiral, with deeply concave apical
surface and base; aperture trapezoidal
with convex outer lip, sharp. Protoconch
paucispiral, ca. 0.2 mm in diameter.
Teleoconch whorls smooth with fine
growth lines, often glossy, strongly
keeled at both apical and basal sides;
suture impressed; aperture nearly ortho-
cline, trapezoidal, convex outer lip
sharp.
Only two species are known globally
of which one is found in the NE
Atlantic: Eudaronia aperta (Sykes, 1925).
Distribution: Iceland, Western Norway
to Portugal (W
ARÉN
,1991: 80; H
OFFMAN
ET AL
., 2010: 54), Coral Patch Seamount
(H
OFFM AN
& F
REIWALD
, 2017), Plato
Seamount (this study), 250–2000 m.
Remarks: Eudaronia aperta is very
similar to the type species; the cross-
section of the whorl is more rounded
in the type species, whose keels are
weaker and more placed towards the
apex and base. The protoconch is
rough on the nucleus and smooth
towards the edge (W
ARÉN
,1991: fig.
18D).
Eudaronia aperta (Sykes, 1925) (Fig. 11)
Omalogyra aperta Sykes, 1925: 192.
Eudaronia aperta: W
ARÉN
,1991: 80, figs. 14C-D, 18D.
Material examined: Plato Seamount •434 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge.
Eudaronia spirata n. sp. (Figs. 12, 13)
Type material: Holotype, Plato Seamount • 1 live collected specimen (Figs. 13A-C); 33.210°N,
29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral frag-
ments; MNHN-IM-2000-35653. Paratypes: • 1 shell (Paratype 1) and 1 live collected (Paratype 2)
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
15
Figure 11. Eudaronia aperta (Sykes, 1925). A: Plato Seamount – SMT2/DW250, W 1.2 mm; B:
protoconch in apical view W 0.23 mm, same as A; C-E: same locality, H 0.6 mm, W 1.2 mm; F:
protoconch in basal view W 0.20 mm, same as C; G, H: same locality, H 0.6 mm, W 1.2 mm, I:
protoconch in basal view W 0.20 mm, same as G.
Figura 11. Eudaronia aperta (Sykes, 1925). A: Banco Plato - SMT2/DW250, 1,2 mm alto; B: vista
apical de la protoconcha 0,23 mm ancho, misma que A; C-E: misma localidad, 0,6 mm alto, 1,2 mm
ancho; F: vista basal de la protoconcha 0,20 mm ancho, misma que C; G, H: misma localidad, 0,6 mm
alto, 1,2 mm ancho; I: vista basal de la protoconcha 0,20 mm ancho, misma que G.
with dried soft parts (Figs. 13D-G); same data as for holotype; MNHN-IM-2000-35654. • 52 shells;
same data as for holotype; MNHN-IM-2000-35655. • 4 shells; same data as for holotype; SMF 351094.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: spirata (Latin) refers to the spiral cords on the protoconch.
Holotype, with dried soft parts inside
shell (Fig. 13A-C): Very small (H 0.6 mm,
W 1.0 mm) planispiral, with weak keels
on apical and basal sides, translucent
white.
Protoconch: ¾ whorls, nucleus
coarsely sculptured by shallow pits.
Four rough spiral cords visible adapi-
cally and three cords basally. End of
whorl with sharp flexuous lip, W 0.18
mm. Apical and basal view similar.
Transition to teleoconch demarcated by
varix and fine growth markings on the
teleoconch (Fig. 13C, G).
Teleoconch: Planispiral with two
rounded smooth whorls; perfectly
concave spire apically and basally. Two
weak keels placed at the centre of the
apical and basal whorl surfaces. Numer-
ous fine and flexuous growth lines.
100 µm
100 µm
100 µm
A
B
C
D
E
F
H
I
G
Iberus, 38 (Suplemento 9), 2020
16
Figure 12. Eudaronia spirata n. sp. A, B: Plato Seamount – SMT2/DW250, paratype 1, apical view,
W 1.9 mm, apertural view, H 0.9 mm; C: paratype 2, protoconch in basal view, W 0.16 mm.
Figura 12. Eudaronia spirata n. sp. A, B: Banco Plato - SMT2/DW250, paratipo 1, vista apical, 1,9
mm ancho, vista apertural, 0,9 mm alto; C: paratipo 2, vista basal de la protoconcha, 0,16 mm ancho.
Apical and basal sides nearly symmetri-
cal. Suture shallow, impressed.
Aperture 100% of shell height and
35% of shell width, rounded on all sides,
kidney-shaped, perfectly symmetrical.
Peristome blunt, smooth, concavely flex-
uous on parietal side, outer lip nearly
orthocline but flexuous, protruding at
periphery. Callus smooth, nearly disap-
pearing on parietal side, inside of whorl
smooth. Angle of union with penulti-
mate whorl about 80°.
Operculum, multispiral, chitinous,
brown translucent (Fig. 13B).
Variability: Width up to 1.7 mm, pro-
toconch width 0.16-0.18 mm.
Distribution: only known from the
type material.
Remarks: The species is most similar
to Eudaronia aperta, however, the latter
lacks the spiral cordlets on the proto-
conch, and the body whorl is united
with the penultimate whorl over the
rounded peripheral area rather than
over the whole space between keels
resulting in a sharper angle at the
union, about 30° versus about 80° in E.
spirata.
Eudaronia mikra n. sp. (Figs. 14, 15)
Type material: Holotype, Plato Seamount •1 shell (Figs. 15D-G); 33.210°N, 29.287°W; 1450–1500 m;
01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-
35656. Paratypes: • 1 shell (Paratype 1, Figs. 15H-J); same data as for holotype; MNHN-IM-2000-
35657. • 9 shells; same data as for holotype; MNHN-IM-2000-35658. • 2 shells; same data as for
holotype; SMF 351095.
Other material examined: Atlantis Seamount • 2 shells (Figs. 15H-J); 33.971°N, 30.206°W; 677 m;
21 Oct. 2018; M151/23404; grab; SMF 351096. Plato Seamount • 16 shells (some as Eudaronia cf.
mikra n. sp., Fig. 15 K-L); 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: mikra (Greek mikro) refers to the small size of the protoconch.
Holotype, empty shell (Figs. 15A-D):
Very small (H 0.9 mm, W 1.7 mm)
planispiral shell, with strong keels on
apical and basal sides, translucent white.
Protoconch: ¾ whorls, coarsely
sculptured by shallow pits. End of
whorl with sharp flexuous lip, some-
what flaring, W 0.14 mm. Apical and
500 µm
500 µm
50 µm
A
C
B
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
17
Figure 13. Eudaronia spirata n. sp. A: Plato Seamount – SMT2/DW250, holotype, apical view; B:
holotype, apertural view with operculum inside, H 0.6 mm, W 1.0 mm; C: protoconch of the
holotype in apical view W 0.18 mm. D, E: paratype 1, H 0.9 mm, W 1.7 mm, protoconch W
0.18 mm. F, G: paratype 2; F: basal view W 1.2 mm; G: protoconch in basal view W 0.16 mm.
Figura 13. Eudaronia spirata n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apical; B: holotipo en
vista apertural con opérculo en el interior, 0,6 mm alto, 1,0 mm ancho; C: vista apical de la protoconcha
del holotipo 0,18 mm ancho; D, E: paratipo 1, 0,9 mm alto, 1,7 mm ancho, protoconcha 0,18 mm ancho.
F, G: paratipo 2; F: vista basal 1,2 mm ancho; G: vista basal de la protoconcha 0,16 mm ancho.
basal view similar. Transition to teleo-
conch demarcated by lip and change in
sculpture (Figs. 15C, G, J).
Teleoconch: Planispiral with three
rounded smooth whorl; perfectly
concave spire apically and basally, sym-
metrical. Two strong keels with smooth
cords placed at the centre of the apical
side and more towards periphery on the
basal surface. On the first teleoconch
whorl, 24 broad and straight axial ribs
merging into the spiral cords; ribs
extending towards suture at periphery.
Axial ribs fading on second whorl; third
whorl smooth. Numerous fine growth
lines. Suture deeply impressed.
Aperture 100% of shell height and
28% of shell width, rounded on parietal
and peripheral sides, weakly angular at
both keels, nearly symmetrical. Peris-
tome blunt, smooth, concavely flexuous
on parietal side, outer lip nearly ortho-
cline but flexuous, protruding at periph-
ery. Callus smooth, fading away on pari-
etal side, inside of whorl smooth. Angle
of union with penultimate whorl about
40°.Variability: Width up to 2.0 mm, pro-
toconch width 0.13-0.14 mm. Some of
the shells (Figure 15 K-L) from Plato
Seamount, DW242 have the ribs contin-
ued over the subsequent whorls, yet
definitely evanescent compared to
Adeuomphalus densicostatus.
Distribution: SASC, Plato and
Atlantis Seamounts.
100 µm
100 µm
A
B
C
D
E
F
G
Iberus, 38 (Suplemento 9), 2020
18
Figure 14. Eudaronia mikra n. sp. A, B: Plato Seamount – SMT2/DW250, holotype, apical view,
W 1.7 mm, apertural view, H 0.9 mm; C: paratype 1, protoconch in basal view, W 0.14 mm.
Figura 14. Eudaronia mikra n. sp. A, B: Banco Plato - SMT2/DW250, holotipo, vista apical, 1,7 mm
ancho, vista apertural, 0,9 mm alto; C: paratipo 1, vista basal de la protoconcha, 0,14 mm ancho.
Remarks: Eudaronia mikra differs strik-
ingly from the two previous species in
having distinct axial riblets on the early
part of the teleoconch, very much in the
style of Adeuomphalus spp. E. aperta, has a
larger protoconch and weaker spiral cords.
Eudaronia spirata n. sp. has spiral cordlets
on its protoconch, which is also larger.
Family not assigned
Genus Adeuomphalus Seguenza, 1876
Type taxon: Adeuomphalus ammoniformis Seguenza, 1876 by monotypy, Pliocene to Lower Pleis-
tocene, Sicily, Italy.
K
ANO ET AL
. (2009) reviewed this genus
and placed it in Seguenzioidea, but its fam-
ily is currently unassigned. These authors
provided a detailed diagnosis: shell small,
up to 3 mm in diameter, colourless, almost
planispiral with concave apical surface and
base. Protoconch paucispiral, about 0.2 mm
in diameter. Teleoconch whorls sculptured
with straight or flexuous axial ribs, often
keeled at both apical and basal sides; suture
deeply impressed; aperture nearly ortho-
cline, horseshoe-shaped.
Twelve Recent species are known
globally, three of which live in bathyal
zones of the NE Atlantic: A. ammoni-
formis Seguenza, 1876, A. densicostatus
(Jeffreys, 1884) and A. sinuosus (Sykes,
1925). All these NE Atlantic species were
found on the SASC and two additional
new species are described herein.
Adeuomphalus ammoniformis Seguenza, 1876 (Figs. 16H-L)
Adeuomphalus ammoniformis Seguenza, 1876: 10; K
ANO ET AL
., 2009: 401-403, figs. 1F-I.
Material examined: Plato Seamount • 3 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993;
SMT2/DW242; dredge. • 1 shell; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
500 µm
500 µm
50 µm
A
C
B
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
19
Figure 15. Eudaronia mikra n. sp. A-C: Plato Seamount – SMT2/DW250, holotype, apical and
apertural views H 0.9 mm, W 1.7 mm; D: protoconch of the holotype in apical view W 0.14 mm;
E, F: same locality, paratype 1, basal and apertural views, H 0.8 mm, W 1.6 mm; G: protoconch
in basal view W 0.14 mm, same as E; H, I: Atlantis Seamount – M151/23404, apical view and
apertural views H 0.9 mm, W 1.7 mm; J: protoconch in apical view W 0.13 mm, same as H; K:
Eudaronia cf. mikra n. sp., Plato Seamount – SMT2/DW242, a small shell with ribbing continued
until second whorl, apical view W 0.95 mm; L: protoconch, same as K.
Figura 15. Eudaronia mikra n. sp. A-C: Banco Plato - SMT2/DW250, holotipo, vistas apical y aper-
tural, 0,9 mm alto, 1,7 mm ancho; D: vista apical de la protoconcha del holotipo 0,14 mm ancho; E,
F: misma localidad, paratipo 1, vistas basal y apertural, 0,8 mm alto, 1,6 mm ancho; vista basal de la
protoconcha 0,14 mm ancho, misma que E; H, I: Banco Atlantis - M151/23404, vistas apical y aper-
tural 0,9 mm alto, 1,7 mm ancho; J: vista apical de la protoconcha 0,13 mm ancho, misma que H; K:
Eudaronia cf. mikra n. sp., concha pequeña con costillas continuadas hasta la segunda vuelta, Banco
Plato - SMT2/DW242, vista apical W 0,95 mm; L: protoconcha, misma que K.
A
B
C
D
E
F
H
I
GJ
KL
100 µm
100 µm 100 µm
100 µm
Iberus, 38 (Suplemento 9), 2020
20
Figure 16. Adeuomphalus densicostatus (Jeffreys, 1884). A-C: Plato Seamount – SMT2/DW250, H
0.6 mm, W 1.1 mm; D: apical view of the protoconch W 0.15 mm, same as A; E-G: H 0.7 mm,
W 1.3 mm. H-J: Adeuomphalus ammoniformis Seguenza, 1876, Plato Seamount – SMT2/DW250.
H 0.57 mm, W 1.07 mm; K: apical view of the protoconch W 0.13 mm, same as H; L:
microsculpture, same as H.
Figura 16. Adeuomphalus densicostatus (Jeffreys, 1884). A-C: Banco Plato - SMT2/DW250,0,6 mm
alto, 1,1 mm ancho; D: vista apical de la protoconcha 0,15 mm ancho, misma que A; E-G: 0,7 mm
alto, 1,3 mm ancho. H-J: Adeuomphalus ammoniformis Seguenza, 1876, Banco Plato -
SMT2/DW250, 0,57 mm alto, 1,07 mm ancho; K: vista apical de la protoconcha 0,13 mm ancho,
misma que H; L: microescultura, misma que H.
Distribution: dead or fossil in
western Mediterranean (W
ARÉN
, 1991),
living in the Alboran sea (G
OFAS ET AL
.
2011). Hatton- and Rockall Banks
(H
OFFMAN ET AL
., 2010), Porcupine
Seabight (F
REIWALD
& B
ECK
, 2007), Lusi-
A
B
C
D
E
F
H
I
GJ
K
L
100 µm 100 µm 100 µm
tanian seamounts and banks (B
ECK ET
AL
., 2006; H
OFFMAN
& F
REIWALD
, 2017),
Plato Seamount (this study).
Remarks: Adeuomphalus ammoniformis
is similar to A. densicostatus, but the
axial ribs of the present species are
stronger, more sinuous and more widely
spaced (K
ANO ET AL
., 2009) and the two
spiral cords form keels and are placed
closer to the periphery.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
21
Adeuomphalus densicostatus (Jeffreys, 1884) (Figs. 16A-G)
Homalogyra densicostata Jeffreys, 1884: 129, pl. 10, fig. 1
Adeuomphalus densicostatus: K
ANO ET AL
., 2009: 403-404, figs. 1A-E.
Material examined: Azores, Mar da Prata • 1 shell; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018;
M151/23168; grab. Plato Seamount • 2 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge.
Distribution: dead or fossil in western
Mediterranean (K
ANO ET AL
., 2009), Hatton-
and Rockall Banks (H
OFFMAN ET AL
., 2010),
Lusitanian seamounts, banks and off west-
ern Iberian Peninsula (K
ANO ET AL
., 2009;
H
OFFMAN
& F
REIWALD
, 2017), Azores, Plato
Seamount (this study). Watson (1886: 677)
reported this species from off Culebra
Island, West Indies, but F
ERNÁNDEZ
-
G
ARCÉS ET AL
. (2019) described several sim-
ilar species from the Caribbean and a re-
Adeuomphalus cf. sinuosus (Sykes, 1925) (Fig. 17)
Homalogyra sinuosa Sykes, 1925: 192, pl. 9, fig. 8.
Adeuomphalus sinuosus: K
ANO ET AL
., 2009: 408, figs. 4A-B.
Material examined: Plato Seamount • 13 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge.
Distribution: off southern Portugal
(39°42’N, 09°43’W, 1990 m), Plato Sea -
mount (this study, 1500 m).
Remarks: Adeuomphalus sinuosus is a rare
species only known from two bathyal loca-
tions. Compared to A. densicostatus, the
axial ribs of the present species are stronger,
more sinuous and more widely spaced
(K
ANO ET AL
., 2009) and there are no keels
whatsoever on the sides. The syntypes of A.
sinuosus and a further specimen collected
on the Galicia Bank have axial ribs fading
out on the last whorls, contrary to the spec-
imens from Plato. Specimens, however, are
too few for a conclusion to be reached.
F
ERNÁNDEZ
-G
ARCÉS ET AL
. (2019: 4-5, figs.
1A-F) described a very similar A. diegoale-
jandroi from off North Cuba (1455 m),
which has a more pronounced microsculp-
ture between the axial ribs.
Adeuomphalus axistriatus n. sp. (Figs. 18, 19)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 19A-D); 33.210°N, 29.287°W; 1450–1500 m; 01
Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-35659.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: axistriatus (Latin) refers to the straight axial rib sculpture.
examination of the specimen would be
needed to ascertain the record.
Remarks: see remarks under Adeuom-
phalus ammoniformis for differences with
this species. As in A. ammoniformis, the
axial ribs on our specimens have faded on
the periphery; this is considered a variety.
Adeuomphalus xerente Absalão, 2009 from
off Brazil may be a junior synonym of A.
densicostatus, but our material is not suf-
ficient for this to be ascertained.
Iberus, 38 (Suplemento 9), 2020
22
Figure 17. Adeuomphalus cf. sinuosus (Sykes, 1925). A-C: Plato Seamount – SMT2/DW250, H 0.9
mm, W 2.0 mm; D: protoconch in basal view W 0.16 mm, same as A; E: microsculpture, same as
C; F-H: same locality, H 0.9 mm, W 1.8 mm; I: protoconch in apical view W 0.18 mm, same as F.
Figura 17. Adeuomphalus cf. sinuosus (Sykes, 1925). A-C: Banco Plato - SMT2/DW250, 0,9 mm
alto, 2,0 mm ancho; D: vista basal de la protoconcha 0,16 mm ancho, misma que A; E: microescultura,
misma que C; F-H: misma localidad, 0,9 mm alto, 1,8 mm ancho; I: vista apical de la protoconcha
0,18 mm ancho, misma que F.
Holotype, an empty shell (Figs. 19A-D):
Very small (H 0.5 mm, W 1.2 mm)
planispiral shell with strong straight
axial rib sculpture, without spiral cords,
white.
Protoconch: ¾ whorls, coarsely
sculptured by flat pits, straight thick
and smooth varix, W 0.14 mm. Apical
and basal view very similar. Transition
to teleoconch clear by varix and change
in sculpture (Fig. 19D).
Teleoconch: Planispiral with two
rounded whorls, with smooth straight
ribs, regularly spaced, continuous from
A
B
C
DE
F
H
I
G
100 µm 100 µm 100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
23
Figure 18. Adeuomphalus axistriatus n. sp. A: Plato Seamount – SMT2/DW250, holotype, apical
view W 1.2 mm, apertural view H 0.5 mm; C: protoconch in basal view, W 0.14 mm.
Figura 18. Adeuomphalus axistriatus n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apical
1,2 mm ancho, vista apertural 0,5 mm alto; C: vista basal de la protoconcha, 0,14 mm ancho.
Figure 19. Adeuomphalus axistriatus n. sp. A-C: Plato Seamount – SMT2/DW250, holotype, H
0.5 mm, W 1.2 mm; D: protoconch in apical view W 0.14 mm.
Figura 19. Adeuomphalus axistriatus n. sp. A-C: Banco Plato – SMT2/DW250, holotipo, 0,5 mm
alto, 1,2 mm ancho; D: vista apical de la protoconcha 0,14 mm ancho.
A
B
CD100 µm
200 µm
200 µm
50 µm
A
C
B
apical to basal end, 19 ribs on first
whorl, 42 ribs on the second whorl.
Areas between ribs smooth with very
fine growth lines. Apical to basal sides
nearly symmetrical. Suture very deep.
Aperture 100% of shell height and
35% of shell width, rounded on all sides,
kidney-shaped, slightly oblique adapi-
cally. Peristome blunt, smooth, con-
cavely flexuous on parietal side, outer
lip nearly orthocline. Callus smooth,
thinning on parietal side, inside of whorl
smooth with weak axial undulations fol-
lowing external sculpture. Angle of
union with penultimate whorl 0°.
Variability: unknown.
Distribution: only known from the
type locality.
Remarks: The species is placed in the
genus Adeuomphalus based on the mor-
phology of the symmetrical planispiral
shell, sculpture and protoconch. It is
similar to Adeuomphalus densicostatus,
however, this species has flexuous ribs
and two spiral cords forming keels (Figs.
16A-G). It is also similar to A. ammoni-
formis, which has less but stronger axial
ribs and also two spiral keels (Figs. 16H-
L). Adeuomphalus sinuosus also lacks the
spiral ribs but has sharp, flexuous axial
ribs (Figs. 17A-I). F
ERNÁNDEZ
-G
ARCÉS ET
AL
. (2019: 5, figs. 2A-F) described a very
similar A. valentinae from off the north-
ern coast of Cuba (1455 m); that species
has micro-cordlets between the axial ribs
whereas A. axistriatus n. sp. is smooth.
Iberus, 38 (Suplemento 9), 2020
24
Figure 20. Adeuomphalus curvistriatus n. sp. A: Plato Seamount – SMT2/DW250, holotype, apical
view W 2.3 mm, apertural view H 1.0 mm; C: protoconch in basal view, W 0.20 mm.
Figura 20. Adeuomphalus curvistriatus n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apical
2,3 mm ancho, vista apertural 1,0 mm alto; C: vista basal de la protoconcha, 0,20 mm ancho.
Adeuomphalus curvistriatus n. sp. (Figs. 20, 21)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 21A-E); 33.210°N, 29.287°W; 1450–1500 m; 01
Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-35660.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: curvistriatus (Latin) refers to the flexuous axial rib sculpture.
Holotype, an empty shell (Figs. 21A-E):
Very small (H 1.0 mm, W 2.3 mm)
planispiral shell with flexuous axial rib
sculpture, without spiral cords on body
whorl, white.
Protoconch: ¾ whorls, nucleus
coarsely sculptured by flat pits, end of
whorl smooth with straight thick and
smooth varix, W 0.20 mm. Apical and
basal view similar. Transition to teleo-
500 µm 500 µm
100 µm
A
C
B
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
25
Figure 21. Adeuomphalus curvistriatus n. sp. A-C: Plato Seamount – SMT2/DW250, holotype, H
1.0 mm, W 2.3 mm; D: protoconch in basal view W 0.20 mm; E: microsculpture.
Figura 21. Adeuomphalus curvistriatus n. sp. A-C: Banco Plato – SMT2/DW250, holotipo, 1,0 mm
alto, 2,3 mm ancho; D: vista basal de la protoconcha 0,20 mm ancho; E: microescultura.
conch clear by varix and change in
sculpture (Fig. 21D).
Teleoconch: Planispiral with 2 ¼
rounded whorls with smooth flexuous
ribs on apical and on basal surfaces,
faded on periphery, 24 ribs on first
whorl, 43 on the body whorl. Two
smooth spiral cords on first ½ whorl,
merged into the axial ribs. Axial ribs
weak on apical and basal ends of first
whorl, fine growth lines between ribs.
Strong growth markings between ribs
on body whorl. Apical to basal sides
nearly symmetrical. Suture deep.
Aperture 100% of shell height and
35% of shell width, rounded on all sides,
kidney-shaped, perfectly symmetrical.
Peristome blunt, smooth, concavely flex-
uous on parietal side, outer lip nearly
orthocline but flexuous, protruding at
periphery. Callus smooth, nearly disap-
pearing on parietal side, inside of whorl
smooth. Angle of union with penulti-
mate whorl 0°.
Variability: unknown.
Distribution: only known from the
type locality.
Remarks: The species is similar to
Adeuomphalus densicostatus, however, this
species has two spiral cords and lacks the
marked growth lines between ribs (Figs.
16A-G). A deuomphal us axistriatus has
straight axial ribs, which are continuous
on the peripheral whorl surface, and has
a smaller protoconch (Figs. 18A-D).
Adeuomphalus sinuosus has strong and
sharp flexuous ribs, which are continuous
across the periphery (Figs. 17A-I).
Genus Akritogyra Warén, 1992
Type taxon: Akritogyra curvilineata Warén, 1992 by original designation. The type locality is the
Bay of Biscay, 48°47’N - 11°13’W, 1430–1550 m.
W
ARÉN
(1992) originally placed Akri-
togyra within Skeneidae (Trochoidea),
but K
ANO ET AL
. (2009) relocated the
genus in Seguenzioidea, even though its
family is currently unassigned. W
ARÉN
(1992) provided a detailed diagnosis of
the genus based on Akritogyra similis (Jef-
freys, 1883), A. conspicua (Monterosato,
1880) and A. curvilineata Warén, 1992.
The shell has the following characteris-
100 µm
A
BD
E
C
100 µm
tics (W
ARÉN
1992): protoconch of 0.5 - 0.6
whorls, finely granulate. First 0.1 - 0.5
teleoconch whorl often sculptured with
irregular net-sculpture or by short lines,
or smooth. An uneven, irregularly pitted
surface in umbilicus. Up to 2.5 convex
teleoconch whorls.
Four species are known in the NE
Atlantic: the type species Akritogyra
curvilineata Warén, 1992, A. conspicua
(Monterosato, 1880) from the Mediter-
ranean Sea, A. similis (Jeffreys, 1883)
from off Iceland and NW Europe, A.
helicella Warén, 1993 from off Iceland.
Iberus, 38 (Suplemento 9), 2020
26
Figure 22. Akritogyra similis (Jeffreys, 1883). A-B: Plato Seamount – SMT2/DW250, H 1.5 mm,
W 1.7 mm; C: same locality, apical view, W 1.7 mm; D: protoconch W 0.27 mm, same as C.
Figura 22. Akritogyra similis (Jeffreys, 1883). A-B: Banco Plato - SMT2/DW250, 1,5 mm alto, 1,7
mm ancho; C: vista apical, 1,7 mm ancho; D: protoconcha 0,27 mm ancho, misma que C.
Akritogyra similis (Jeffreys, 1883) (Fig. 22)
Cyclostrema simile Jeffreys, 1883: 92, pl. 19 fig. 4.
Akritogyra similis: W
ARÉN
, 1992: 161-162, figs. 13E-F, 14A-B, 15C.
Material examined: Azores, Mar da Prata • 2 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. • 1 shell; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018; M151/23168; grab. Atlantis
Seamount • 1 shell; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Plato Seamount •
6 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. • 13 shells; 33.210°N,
29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
Distribution: NE Atlantic: Iceland,
Bay of Biscay, NW Morocco (W
ARÉN
,
1992), Rockall and Hatton Banks
(H
OFFMAN ET AL
.2010), Azores, SASC
(D
AUTZENBERG
, 1927 and this study),
593–2102 m.
Remarks: The shell of Akritogyra similis
has straight growth lines and lip and a
smooth surface of whorls. The Mediter-
ranean species A. conspicua(Monterosato,
1880) is similar but has a smaller proto-
conch and teleoconch (W
ARÉN
, 1992).
A
B
D
C
100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
27
W
ARÉN
(1992) provided a diagnosis for
the shell: small, tall-spired, with fine sculp-
ture of irregularly branching or anasto-
mosing lines, usually of mainly spiral direc-
tion. Protoconch with granular sculpture.
Four species are currently known in
the NE Atlantic: Anekes undulisculpta
Bouchet & Warén, 1979, A. affinis (Jeffreys,
1883), A. paucistriata Warén, 1992, and A.
sculpturata Warén, 1992.
Anekes paucistriata Warén, 1992 (Fig. 23)
Anekes paucistriata Warén, 1992: 165-166, figs. 19D, 20B-D, 21A, 22B
Material examined: Azores, Mar da Prata • 82 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. • 39 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab. • 1 shell;
37.666°N, 25.966°W; 961 m; 09 Oct. 2018; M151/23121; grab. Atlantis Seamount • 270 shells; 34.082°N,
30.255°W; 335–340 m; 02 Feb. 1993; SMT2/DW255; dredge. • 270 shells; 33.997°N, 30.203°W; 420–460
m; 02 Feb. 1993; SMT2/DW258; dredge. • 94 shells; 34.080°N, 30.248°W; 330 m; 04 Feb. 1993;
SMT2/TS270; suprabenthic sled. • 8 shells; 34.086°N, 30.226°W; 280 m; 05 Feb. 1993; SMT2/DW274;
dredge. Tyro Seamount • 5 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278;
dredge. Plato Seamount • 26 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242;
dredge. Hyères Seamount• 1 shell; 31.387°N, 28.892°W; 480 m; 15 Jan. 1991; SMT2/DW182; dredge.
• 1 shell; 31.465°N, 28.985°W; 700–750 m; 17 Jan. 1998; SMT2/DW192; dredge. Great Meteor Sea-
mount • 5 shells; 29.565°N, 28.339°W; 948 m; 25 Oct. 2018; M151/23425-R1; ROV sample. • 6 shells;
29.565°N, 28.332°W; 945 m; 25 Oct. 2018; M151/23425-R4; ROV sample. • 16 shells; 29.565°N,
28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample. • 14 shells; 29.568°N, 28.339°W; 855
m; 25 Oct. 2018; M151/23425-R9; ROV sample. • 1 shell; 30.086°N, 28.726°W; 906 m; 26 Oct. 2018;
M151/23429-R8; ROV sample. Little Meteor Seamount • 12 shells; 29.654°N, 29.015°W; 852 m; 27
Oct. 2018; M151/23436; grab.
Distribution: off southwestern Portu-
gal and Mediterranean Sea (W
ARÉN
,
1992; M
ETZGER
, 2005; B
ECK ET AL
., 2006),
Porcupine Basin (F
REIWALD
& B
ECK
,
2007), Rockall Bank (H
OFFMAN ET AL
,
2010), Madeira and Seine Seamount
(S
EGERS ET AL
. 2009), Coral Patch
Seamount (H
OFFMAN
& F
REIWALD
,
2017), Canary Is. (O
RTEGA
& G
OFAS
,
2019) SASC and the Azores (this study),
167–1500 m.
Remarks: The species can be identified
by the flexuous sharp lip and the sculp-
ture of fine anastomosing threads on the
initial teleoconch and the sparsely-
spread, short branching threads on the
last two whorls. Its suture is shallow,
impressed. An adult of A. paucistriata was
found afloat in a plankton tow far from
the bottom (W
ARÉN
, 1992), a circum-
stance which could explain a very broad
distribution across seamounts.
Anekes mikrosculpta n. sp. (Figs. 24, 25)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 25A-E); 33.210°N, 29.287°W; 1450–1500 m;
01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-
35661. Paratypes: • 2 shells (Figs. 25F-I); same data as for holotype; MNHN-IM-2000-35662. • 37
shells; same data as for holotype; MNHN-IM-2000-35663.
Other material examined: Azores, Mar da Prata • 1 shell; 37.666°N, 25.966°W; 961 m; 09 Oct. 2018;
M151/23121; grab. • 10 shells; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018; M151/23168; grab. Atlan-
tis Seamount • 2 shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993; SMT2/DW264; dredge. • 30
Genus Anekes Bouchet & Warén, 1979
Type taxon: Anekes undulisculpta Bouchet & Warén, 1979 by original designation, Arctic, abyssal. The genus
was included in Seguenzioidea by K
ANO ET AL
. (2009) and this is reflected in M
OLLUSCA
B
ASE
(2020).
Iberus, 38 (Suplemento 9), 2020
28
Figure 23. Anekes paucistriata Warén, 1992. A, B: Great Meteor Seamount – M151/23425-ROV6,
A-B: H 1.3 mm, W 1.1 mm; C: same locality, W 1.0 mm; D: protoconch W 0.22 mm and
microsculpture of teleoconch whorls 1 & 2, same as C; E: microsculpture, same as A; F: same
locality, H 1.0 mm, W 0.9 mm; G: same locality, H 1.0 mm, W 0.9 mm. H: Tyro Seamount –
SMT2/TS270, H 0.9 mm, W 0.8 mm; I: same locality, H 1.4 mm, W 1.1 mm; J: same locality,
W 0.9 mm; K: protoconch W 0.22 mm, same as J.
Figura 23. Anekes paucistriata Warén, 1992. A, B: Gran Banco Meteor - M151/23425-ROV6, 1,3
mm alto, 1,1 mm ancho; C: misma localidad, 1,0 mm ancho; D: protoconcha 0,22 mm ancho y micro-
escultura de vueltas 1 y 2 de teleoconcha, misma que C; E: microescultura, misma que A; F: misma
localidad, 1,0 mm alto, 0,9 mm ancho; G: misma localidad, 1,0 mm alto, 0,9 mm ancho. H: Banco
Tyro - SMT2/TS270, 0,9 mm alto, 0,8 mm ancho; I: misma localidad, 1,4 mm alto, 1,1 mm ancho;
J: misma localidad, 0,9 mm ancho; K: protoconcha 0,22 mm ancho, misma que J.
shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. Tyro Seamount• 11 shells (Figs.
25J-M of two shells); 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge. Plato
Seamount • 4 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. • 1 shell;
33.207°N, 29.247°W; 1700–1800 m; 01 Feb. 1992; SMT2/DW249; dredge. Great Meteor Seamount •
3 shells; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample. • 2 shells; 29.568°N,
28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. • 1 shell; 30.086°N, 28.726°W; 906 m;
26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Seamount• 2 shells; 29.654°N, 29.015°W;
865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 47 shells; 29.654°N, 29.015°W; 852 m; 27 Oct.
2018; M151/23436; grab. • 1 shell; 29.654°N, 29.014°W; 811 m; 27 Oct. 2018; M151/23437; grab.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: The name refers to the microscopic sculpture (Greek: mikro for small).
ABC
D
E
F
HI
G
JK
100 µm
100 µm
100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
29
Figure 24. Anekes mikrosculpta n. sp. A: Plato Seamount – SMT2/DW250, holotype, apertural
view, H 2.1 mm; B: Tyro Seamount – SMT2/DW278, apical view of finely granulated proto-
conch, W 0.39 mm.
Figura 24. Anekes mikrosculpta n. sp. A: Banco Plato - SMT2/DW250, holotipo, vista apertural, 2,1
mm alto; B: Banco Tyro - SMT2/DW278, vista apical de la protoconcha finamente granulada, 0,39
mm ancho.
Holotype, an empty shell (Figs. 24A,
25A-E): Small (H 2.1, W 2.3 mm), thin
and fragile shell with a low spire (apical
angle 100°) and raised apex, deep
suture, a fine network of microsculpture
covering the entire teleoconch, translu-
cent white.
Protoconch: Simple nucleus, ½
whorl, finely granulated, with convex
sharp lip, somewhat flaring, W 0.38
mm. Transition to teleoconch clear by
change in sculpture (Figs. 25D of holo-
type, 25I,M of paratype and additional
shell).
Teleoconch: 2 ¼ rounded whorls, all
whorls convex, fine network structure of
oblique anastomosing and branching
cordlets on the second and body whorls
(Fig. 25E). Fine oblique and flexuous
growth lines, few stronger growth
marks, angle with spire axis at periph-
ery about 30°. Umbilicus wide open.
Aperture 60% of shell height, nearly
circular, slightly angular basally and
adapically at union with penultimate
whorl. Columellar lip sharp, partly cov-
ering umbilicus. Outer lip sharp, proso-
cline, slightly flexuous. Callus smooth,
inside of whorl smooth. Section of union
with penultimate whorl short, with an
angle nearly 0°.
Variability: Little variability in shell
shape, some variability in density of net
sculpture, height up to 2.1 mm, proto-
conch width 0.36–0.38 mm.
Distribution: SASC and Azores,
677–1800 m.
Remarks: The species is placed in the
genus Anekes based on the protoconch,
and of the diagnostic network sculpture
which continues into the open umbili-
cus. The type species A. undulisculpta,
from the Norwegian Sea, has a more
raised spire and more spirally oriented
microsculpture. Anekes sculpturata has a
rough sculpture and straight growth
lines. Anekes affinis has a straight lip and
a much looser mesh of microsculpture.
Anekes paucistriata has a smooth whorl
surface with scarce oblique cordlets.
Akritogyra curvilineata is similar to this
species because it also has oblique flexu-
ous growth markings but it lacks a retic-
ulate microsculpture.
100 µm
AB
1 mm
Iberus, 38 (Suplemento 9), 2020
30
Figure 25. Anekes mikrosculpta n. sp. A-C: Plato Seamount – SMT2/DW250, holotype, H 2.1
mm, W 2.3 mm; D: protoconch of the holotype, W 0.38 mm; E: microsculpture; F, G: paratype
1, same locality, H 2.0 mm, W 2.1 mm; H: paratype 2, same locality, apical view, W 1.8 mm; I:
protoconch W 0.36 mm, same as H; J, K: Tyro Seamount – SMT2/DW278, H 2.0 mm, W 2.0
mm; L: same locality, apical view, W 1.6 mm; M: protoconch W 0.39 mm, same as L.
Figura 25: Anekes mikrosculpta n. sp. A-C: Banco Plato - SMT2/DW250, holotipo, 2,1 mm alto, 2,3
mm ancho; D: protoconcha del holotipo 0,38 mm ancho; E: microescultura; F, G: paratipo 1, misma
localidad, 2,0 mm alto, 2,1 mm ancho; H: paratipo 2, misma localidad, vista apical, 1,8 mm ancho; I:
protoconcha 0,36 mm ancho, misma que H; J, K: Banco Tyro - SMT2/DW278, 2,0 mm alto, 2,0 mm
ancho; L: misma localidad, vista apical, 1,6 mm ancho; M: protoconcha 0,39 mm ancho, misma que L.
A
B
CD
E
F
H
I
G
J
K
L
M
100 µm
100 µm
100 µm
100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
31
Figure 26. Anekes anderswareni n. sp. A: Little Meteor Seamount – M151/23436, holotype, aper-
tural view H 1.9 mm; B: apical view of finely granulated protoconch, W 0.33 mm.
Figura 26. Anekes anderswareni n. sp. A: Pequeño Banco Meteor - M151/23436, holotipo, vista aper-
tural 1,9 mm alto; B: vista apical de la protoconcha finamente granulada, 0,33 mm ancho.
Anekes anderswareni n. sp. (Figs. 26, 27)
Type material: Holotype, Little Meteor Seamount • 1 shell (Figs. 27A-C); 29.654°N, 29.015°W; 852
m; 27 Oct. 2018; M151/23436; grab, in bioclastic sand with dead coral fragments. Paratypes: • 3
shells (Figs. 27D-H); same data as for holotype; MNHN-IM-2000-35664. • 2 shells; same data as for
holotype; SMF 351097.
Other material examined: Azores, Mar da Prata • 10 shells; 37.673°N, 25.925°W; 595 m; 08 Oct.
2018; M151/23111; grab. • 36 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab.
• 6 shells; 37.666°N, 25.966°W; 961 m; 09 Oct. 2018; M151/23121; grab. • 1 shell; 37.659°N, 25.789°W;
599 m; 19 Oct. 2018; M151/23181; box core. Azores, Açor Bank • 9 shells; 38.156°N, 29.084°W; 339
m; 13 Oct. 2018; M151/23139; grab. Atlantis Seamount • 4 shells; 34.086°N, 30.226°W; 280 m; 05
Feb. 1993; SMT2/DW274; dredge. • 63 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404;
grab. Tyro Seamount • 32 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278;
dredge. Plato Seamount • 4 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242;
dredge. • 121 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Hyères
Seamount • 6 shells; 31.387°N, 28.892°W; 480 m; 15 Jan. 1991; SMT2/DW182; dredge. Little Meteor
Seamount • 2 shells; 29.654°N, 29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 1
shell; 29.654°N, 29.014°W; 811 m; 27 Oct. 2018; M151/23437; grab.
Type locality: Little Meteor Seamount – 29.654°N – 29.015°W, 852 m.
Etymology: The specific name anderswareni is honouring the significant contributions of Anders
Warén to the knowledge of the NE Atlantic molluscs, particularly the taxonomic review of
skeneimorphs.
Holotype, an empty shell (Figs. 27A-C):
Small (H 1.9 mm, W 1.7 mm), thin and
fragile shell with a regularly raised
outline, convex whorls, spire apical
angle about 75°, with fine irregular
umbilical cordlets, translucent white.
Protoconch: ¾ whorls, finely granu-
lar, convex sharp lip, W 0.34 mm. Transi-
tion to teleoconch clear by lip (Fig. 27C).
Teleoconch: 2 ¾ rounded whorls, su-
ture shallow impressed. Whorl surface
smooth with fine growth lines at about 30°
100 µm
A
B
500 µm
Iberus, 38 (Suplemento 9), 2020
32
Figure 27. Anekes anderswareni n. sp. A, B: Little Meteor Seamount – M151/23436, holotype, H
1.9 mm, W 1.7 mm; C: protoconch of the holotype, W 0.33 mm; D: paratype 1, same locality, W
1.5 mm; E: paratype 2, same locality, H 2.0 mm, W 1.9 mm; F, G: paratype 3, same locality, H
1.7 mm, W 1.7 mm; H: protoconch, same as F; I: Plato Seamount – SMT2/DW250, H 2.1 mm,
W 1.9 mm; J: protoconch W 0.37 mm, same as I; K: same locality, H 2.0 mm, W 1.9 mm.
Figura 27. Anekes anderswareni n. sp. A, B: Pequeño Banco Meteor - M151/23436, holotipo, 1,9 mm
alto, 1,7 mm ancho; C: protoconcha del holotipo 0,33 mm ancho; D: paratipo 1, misma localidad, 1,5
mm ancho; E: paratipo 2, misma localidad, 2,0 mm alto, 1,9 mm ancho; F, G: paratipo 3, misma locali-
dad, 1,7 mm alto, 1,7 mm ancho; H: protoconcha, misma que F; I: Banco Plato - SMT2/DW250, 2,1
mm alto, 1,9 mm ancho; J: protoconcha 0,37 mm ancho, misma que I; K: 2,0 mm alto, 1,9 mm ancho.
A
B
C
D
E
F
H
I
G
J
K
100 µm
100 µm
100 µm
with spire axis. The first whorl with fine
network of axial and spiral line segments;
network faded away on second whorl.
Base of body whorl with about 10
interrupted, irregular spiral cordlets
outside umbilical area, minor spiral line
segments inside umbilicus. Umbilicus
open, deep.
Aperture 60% of shell height, nearly
circular, angular at the union to penulti-
mate whorl with an angle ca. 90°. Peris-
tome thin and sharp, outer lip proso-
cline. Columella thin and curved. Callus
very thin and smooth, inside of whorl
smooth.
Variability: Most specimens show a
shallow impressed suture; the union of
outer lip with the preceding whorl is at
nearly 90°. Very few specimens show a
deep suture on the body whorl with a
rounded peristome and a tangential
union with the penultimate whorl. The
number of umbilical cordlets is variable;
the holotype has about 10 spiral cordlets
but its umbilicus is predominantly
smooth. Some specimens have up to 12
threads that develop also inside the
umbilicus.
Distribution: SASC, Azores, 280–1500
m. B
ECK ET AL
. (2006: 49) showed a shell
from the Seine Seamount.
Remarks: Placement in the genus
Anekes is based on the morphology of
the protoconch, and on the umbilical
sculpture. This species is similar to
Anekes paucistriata, but the latter has a
more raised spire (apical angle 60° com-
pared to 75° in A. anderswareni), weak
cordlets on the second whorl, and a
chaotic umbilical sculpture. All other
species of Anekes have a fine network
sculpture on the whorl surface.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
33
Anekes umbilisculpta n. sp. (Figs. 28, 29)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 29A-D); 33.210°N, 29.287°W; 1450–1500 m;
01 Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-
35666. Paratypes: • 1 shell (Paratype 1, Fig. 29E); same data as for holotype; MNHN-IM-2000-35667.
• 2 shells (Paratypes 2, 3, Figs. 29F-H); MNHN-IM-2000-35668.
Other material examined: Azores, Albatroz Seamount • 2 shells; 38.116°N, 27.182°W; 770 m; 10
Oct. 2018; M151/23125; grab. Great Meteor Seamount• 1 shell (as Anekes cf umbilisculpta n. sp., Fig.
29J); 29.565°N, 28.332°W; 945 m; 25 Oct. 2018; M151/23425-R4; ROV sample. Little Meteor Sea-
mount • 1 shell; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: umbilisculpta refers to the sculpture, solely present in the umbilical area.
Holotype, an empty shell (Figs. 29A-D):
Very small (H 1.5 mm, W 1.3 mm), thin
and fragile shell with a regularly raised
outline, convex whorls, apical angle
about 70°, microsculpture only present
in umbilicus, translucent white.
Protoconch: ¾ whorls, finely granu-
lar on nucleus, smooth towards lip,
convex sharp lip, W 0.29 mm. Transition
to teleoconch clear by lip and change in
sculpture (Figs. 29D,I).
Teleoconch: 2 ½ rounded whorls,
suture initially deep, shallow impressed
on body whorl. Whorl surface smooth
with numerous irregular growth lines,
prosocline at about 30° with spire axis.
Umbilicus narrow, open, deep;
sculpture of numerous spiralling
dashes, restricted to base of whorl and
umbilicus (Figs. 29B,G).
Aperture 50% of shell height, nearly
circular, angular at the union to penulti-
mate whorl (angle ca. 90°). Peristome;
thin and sharp, outer lip prosocline.
Columella thin and curved. Callus very
thin and smooth, inconspicuous along
parietal area, inside of whorl smooth
(Fig. 29A,E,F,J).
Variability: Height of shells up to 1.7
mm. Observed range of protoconch width
is small: 0.28–0.29 mm (Figs. 29D,I). The
ratio of the aperture height to the shell
height varies between 45% in a large spec-
imen (Fig. 29J) to 55% in a smaller speci-
men (Fig. 29F). Range of apical angle:
59–74°. Slight variation in density of dashes
in umbilical sculpture. The specimen from
the Great Meteor Seamount could be a dif-
ferent, even if closely related species, as it
has a more elevated profile and an incon-
spicuous oblique sculpture on the second
teleoconch whorl (Fig. 28, 29J).
Distribution: SASC, Azores, 852–1500 m.
Remarks: Placement in the genus
Anekes is based on the morphology of
the protoconch and outline and on the
umbilical sculpture. The species is most
similar to A. anderswareni n. sp.
Anekes paucistriata and Anekes ander-
swareni n. sp. have a microsculpture on
the first teleoconch whorl whereas A.
umbilisculpta n. sp. has none. Anekes pau-
cistriata has a dense and chaotic umbili-
cal sculpture and A. anderswareni n. sp.
has a more continuous spiral sculpture
in the umbilical area. All other species in
Anekes have a microsculpture on the
first whorl of the teleoconch and a more
chaotic umbilical sculpture similar to A.
paucistriata.
Iberus, 38 (Suplemento 9), 2020
34
Figure 28. Anekes umbilisculpta n. sp. A: Great Meteor Seamount – M151/23425R4, apertural
view, H 1.7 mm; B: apical view of finely granulated protoconch, W 0.28 mm.
Figura 28. Anekes umbilisculpta n. sp. A: Gran Banco Meteor - M151/23425R4, vista apertural, 1,7
mm alto; B: vista apical de la protoconcha finamente granulada, 0,28 mm ancho.
Anekes varisculpta n. sp. (Figs. 30, 31)
Type material: Holotype, Tyro Seamount• 1 shell (Figs. 31G-H); 33.963°N, 28.373°W; 890–925 m; 06 Feb.
1993; SMT2/DW278; dredge; MNHN-IM-2000-35669. Paratypes: • 2 shells (Fig. 31I); same data as for
holotype; MNHN-IM-2000-35670.• 10 shells; same data as for holotype; MNHN-IM-2000-35671.
Other material examined: Azores, Albatroz Seamount • 2 shells; 38.116°N, 27.182°W; 770 m; 10
Oct. 2018; M151/23125; grab. Atlantis Seamount • 24 shells (Figs. 31A-F); 33.971°N, 30.206°W; 677
m; 21 Oct. 2018; M151/23404; grab. Plato Seamount • 51 shells; 33.197°N, 28.949°W; 690–710 m; 31
Jan. 1993; SMT2/DW242; dredge. • 9 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge. Great Meteor Seamount • 1 shell; 29.565°N, 28.339°W; 948 m; 25 Oct. 2018;
M151/23425-R1; ROV sample. • 1 shell; 29.565°N, 28.332°W; 945 m; 25 Oct. 2018; M151/23425-R4;
ROV sample. • 1 shell; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample. •
1 shell; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. • 1 shell; 30.086°N,
28.726°W; 906 m; 26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Seamount • 5 shells;
29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab. • 1 shell; 29.654°N, 29.014°W; 811 m;
27 Oct. 2018; M151/23437; grab.
Type locality: Tyro Seamount – 33.963°N – 28.373°W, 890–925 m.
Etymology: varisculpta refers the change in sculpture between the first whorl and the body whorl.
100 µm
A
B
500 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
35
Figure 29. Anekes umbilisculpta n. sp. A, B: Plato Seamount, SMT2/DW250, holotype, H 1.5
mm, W 1.3 mm; C: detail of the umbilicus; D: protoconch of the holotype W 0.29 mm; E:
paratype 1, same locality, H 1.4 mm W 1.3 mm; F: paratype 2, same locality, H 1.4 mm, W 1.3
mm; G: detail of microsculpture near umbilicus, same as F; H: paratype 3, same locality, W 1.3
mm; I: protoconch W 0.28 mm, same as H; J: Anekes cf. umbilisculpta n. sp., Great Meteor
Seamount, M151/23425R4, H 1.7 mm, W 1.5 mm, protoconch W 0.28 mm.
Figura 29. Anekes umbilisculpta n. sp. A, B: Banco Plato, SMT2/DW250, holotipo, 1,5 mm alto, 1,3
mm ancho;; C: detalle del ombligo; D: protoconcha del holotipo 0,29 mm ancho; E: paratipo 1, misma
localidad, 1,4 mm alto, 1,3 mm ancho; F: Paratype 2, misma localidad, 1,4 mm alto, 1,3 mm ancho;
G: detalle de la microescultura cerca del ombligo, misma que F; H: paratipo 3, misma localidad, 1,3
mm ancho; I: protoconcha 0,28 mm ancho, misma que H; J: Anekes cf. umbilisculpta n. sp., Gran
Banco Meteor, M151/23425R4, 1,7 mm alto, 1,5 mm ancho, protoconcha 0,28 mm ancho.
A
B
C
D
E
F
H
I
G
J
100 µm
100 µm
100 µm
100 µm
Holotype, an empty shell (Figs. 31G-H):
Very small (H 1.2 mm, W 1.2 mm), thin
and fragile shell with a regularly raised
outline, convex whorls, spire apical
angle about 80°, microsculpture of
branching and anastomosing threads,
translucent white.
Protoconch: ¾ whorls, finely granu-
lar, convex sharp lip, W 0.21 mm. Tran-
sition to teleoconch clear, limited by a
lip (Fig. 31D, F, H).
Teleoconch: 2 ¼ rounded whorls,
suture deep. Whorl surface with
network sculpture, dominating axial
undulating ridges. Irregular flexuous
growth lines at about 30° with spire
axis. The first whorl with fine network
of axial undulating lines connected with
short spiral line segments.
Base of body whorl sculpture coarser,
dominating undulating and discontinu-
ous axial ridges and coarse granules (Fig.
31B). Umbilicus open, deep; sculpture
network of horizontal undulating lines
connected by short axial line segments.
Aperture 58% of shell height, nearly
circular, tangential to penultimate whorl
(angle 0°). Peristome uninterrupted, thin
and sharp, columellar lip slightly
flaring, outer lip prosocline, slightly
flexuous. Columella thin and curved.
Callus very thin and smooth, inside of
whorl smooth (Fig. 31G).
Variability: Height and width of
shells up to 1.3 mm. Range of proto-
conch width is large: 0.21–0.29 mm
(Figs. 31D, F, H). Apical outline angle
76–81°. Suture of body whorl shallow
impressed rather than deep in some
specimens (Fig. 31I, paratype 1). Slight
variation in coarseness of sculpture.
Distribution: SASC, Azores, 677–1500 m.
Remarks: Anekes affinis (Jeffreys, 1883)
and Granigyra inflata (Warén, 1992) have
a similar outline but these species have
a looser mesh of the microsculpture.
Anekes sculpturata Warén, 1992 also has a
similar outline but that species has a
finer net sculpture with branching and
anastomosing lines whereas A.
varisculpta n. sp. has coarse isolated
ridges. Anekes mikrosculpta n. sp. has a
lower spire and a finer, more predomi-
nantly spiral net sculpture. Anekes
undulisculpta Bouchet & Warén, 1979
was described from abyssal depths in
the Norwegian Sea and it has a network
of fine undulating spiral striae. Anekes
paucistriata Warén, 1992 and A. ander-
swareni n. sp. have a predominantly
smooth body whorl with a mostly
umbilical microsculpture.
Iberus, 38 (Suplemento 9), 2020
36
Figure 30. Anekes varisculpta n. sp. A: Tyro Seamount – SMT2/DW278, holotype, apertural view,
H 1.2 mm; B: apical view of finely granulated protoconch, W 0.21 mm.
Figura 30. Anekes varisculpta n. sp. A: Banco Tyro - SMT2/DW278, holotipo, vista apertural, 1,2
mm alto; B: vista apical de la protoconcha finamente granulada, 0,21 mm ancho.
100 µm
AB
500 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
37
Figure 31. Anekes varisculpta n. sp. A, B: Atlantis Seamount – M151/23404, H 1.3 mm, W 1.3
mm; C, D: protoconch W 0.29 mm, same as A-B; E: same locality, W 1.3 mm; F: protoconch W
0.28 mm, same as E; G: Tyro Seamount – SMT2/DW278, holotype, H 1.2 mm, W 1.2 mm; H
protoconch of the holotype W 0.21 mm; I: paratype 1, same locality, H 1.0 mm, W 0.9 mm.
Figura 31. Anekes varisculpta n. sp. A, B: Banco Atlantis - M151/23404, 1,3 mm alto, 1,3 mm
ancho; C, D: protoconcha 0,29 mm ancho, misma que A-B; E: misma localidad, 1,3 mm ancho; F:
protoconcha 0,28 mm ancho, misma que E; G: Banco Tyro - SMT2/DW278, holotipo, 1,2 mm alto,
1,2 mm ancho; H: protoconcha del holotipo 0,21 mm ancho; I: paratipo 1, misma localidad, H 1,0
mm alto, W 0,9 mm ancho.
Genus Granigyra Dall, 1889
Type taxon: Granigyra limata (Dall, 1889) by monotypy, off Cuba, 560 m.
The latest classification includes the
genus in Seguenzioidea, but its family is
currently unassigned (K
ANO ET AL
. 2009;
M
OLLUSCA
B
ASE
, 2020). W
ARÉN
(1992)
provided a diagnosis of the shell of the
genus: small-sized, globular shell with
granular sculpture, round aperture and
open umbilicus.
Five species are known in the NE At-
lantic and Mediterranean Sea: Granigyra
tenera (Jeffreys, 1883) and G. pruinosa
(Jeffreys, 1883) described from off Portu-
AB
C
DEF
H
I
G
100 µm
100 µm
100 µm
100 µm
gal, G. granulifera Warén, 1992 described
from the central Mediterranean,
2460–2500 m and G. arenosa Warén, 1993
described from off the Faroes, 1083 m.
W
ARÉN
(1996) added Granigyra inflata
(Warén, 1992) on the grounds that the
radula and soft parts are more similar to
other Granigyra than to Anekes where it
was originally included based on its
reticulate microsculpture.
Iberus, 38 (Suplemento 9), 2020
38
Granigyra granulifera Warén, 1992 (Fig. 32)
Granigyra granulifera Warén, 1992: 176-177, figs. 32E-F, 34B, 35A-E.
Material examined: Little Meteor Seamount • 2 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018;
M151/23436; grab.
Distribution: Bay of Biscay to
Madeira and the central Mediterranean
Sea (W
ARÉN
, 1992), Little Meteor
Seamount (this study), 700–4300 m.
Remarks: Granigyra granulifera can
be differentiated from G. arenosa
Warén, 1993 by its finer granular sculp-
ture.
Figure 32. Granigyra granulifera Warén, 1992. A, B: Little Meteor Seamount – M151/23436, H
1.6 mm, W 1.7 mm; C: same locality, W 1.8 mm; D: protoconch W 0.28 mm, same as C; E:
micro-sculpture, same as C.
Figura 32. Granigyra granulifera Warén, 1992. A, B: Pequeño Banco Meteor - M151/23436, 1,6 mm
alto, 1,7 mm ancho; C: misma localidad, 1,8 mm ancho; D: protoconcha 0,28 mm ancho, misma que
C; E: microescultura, misma que C.
A
B
C
DE
100 µm 100 µm
The latest classification places the
genus is in Seguenzioidea, but its
family is currently unassigned (K
ANO
ET AL
. 2009; M
OLLUSCA
B
ASE
, 2020).
W
ARÉN
(1989: 6) provided a diagnosis
for the genus: small depressed shell
covered by two sets of narrow and
raised ribs on a smooth surface,
which form a net-sculpture. Umbili cus
wide.
Three species are known in the genus;
all of them from the NE Atlantic: Retigyra
millipunctata (Friele, 1886), R. iheringi
(Dautzenberg & H. Fischer, 1897) from the
Azores, 1600 m, and R. granulosa (Sykes,
1925) from off western Portugal, 1993 m.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
39
Figure 33. Retig yra iheringi (Dautzenberg & H. Fischer, 1897). A-C: Plato Seamount –
SMT2/DW250, H 0.7 mm, W 1.4 mm; D: microsculpture; E: protoconch W 0.32 mm.
Figura 33. Retigyra iheringi (Dautzenberg & H. Fischer, 1897). A-C: Banco Plato - SMT2/DW250,
0,7 mm alto, W 1,4 mm ancho; D: microescultura; E: protoconcha 0,32 mm ancho.
Genus Retigyra Warén, 1989
Type taxon: Cyclostrema millipunctatum Friele, 1886 by original designation, north of Lofoten, ca.
1000 m.
Retigyra iheringi (Dautzenberg & H. Fischer, 1897) (Fig. 33)
Cyclostrema iheringi Dautzenberg & H. Fischer, 1897: 174-175, pl. IV, figs. 5-8.
Material examined: Plato Seamount • 3 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge.
Distribution: The Azores (D
AUTZEN
-
BERG
& H. F
ISCHER
, 1897) and Plato
Seamount (this study), 1450–1600 m.
Remarks: The species has a very
depressed teleoconch with a deep
suture and a wide-open umbilicus; the
lip is slightly flexuous. The sculpture is
a regular diamond-shaped network of
curved lines (Figs. 33D-E). It appears to
be a very rare taxon.
A
BC
DE
100 µm 100 µm
cus, with three strong cords in the
umbilical area (B
USH
, 1897).
Ten species are known of which three
are extant in the NE Atlantic: Moelleriop-
sis messanensis (Seguenza, 1876), described
from Pleistocene outcrop near Messina,
Sicily, Moelleriopsis normani (Dautzenberg
& H. Fischer, 1897) and Moelleriopsis richardi
(Dautzenberg & H. Fischer, 1896) described
from the Azores.
Iberus, 38 (Suplemento 9), 2020
40
Figure 34. Moelleriopsis richardi (Dautzenberg & H. Fischer, 1896). A: Plato Seamount –
SMT2/DW250, H 1.6 mm, W 2.3 mm; B: protoconch W 0.28 mm, same as A; C: W 1.7 mm;
D: apical view, W 2.3 mm; E: protoconch W 0.30 mm, same as D; F: Atlantis Seamount –
M151/23404, H 1.0 mm, W 1.5 mm.
Figura 34. Moelleriopsis richardi (Dautzenberg y H. Fischer, 1896). A: Banco Plato -
SMT2/DW250, 1,6 mm alto, 2,3 mm ancho; B: protoconcha 0,28 mm ancho, misma que A; C: 1,7
mm ancho; D: vista apical, 2,3 mm ancho; E: protoconcha 0,30 mm ancho, misma que D; F: Banco
Atlantis - M151/23404, 1,0 mm alto, 1,5 mm ancho.
Genus Moelleriopsis Bush, 1897
Type taxon: Moelleriopsis abyssicola Bush, 1897 by original designation. Type locality off New
England, 1769 fathoms.
K
ANO ET AL
. (2009) listed the genus
as a “plausible” member of the Seguen-
zioidea, but did not include it in their
molecular dataset. M
OLLUSCA
B
ASE
(2020) includes it in Seguenzioidea with
its family currently unassigned. Never-
theless R
OMANI
& B
OGI
(2016) proposed
to provisionally place Moelleriopsis in the
family Skeneidae. The type species is
quite raised with a deep open umbili-
Moelleriopsis richardi (Dautzenberg & H. Fischer, 1896) (Fig. 34)
Cyclostrema richardi Dautzenberg & H. Fischer, 1896: 484-485, pl. 21 figs. 7-9
Material examined: Atlantis Seamount • 4 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018;
M151/23404; grab. • 9 shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993; SMT2/DW264; dredge.
A
B
CD
E
100 µm 100 µm
F
Distribution: Azores (D
AUTZENBERG
& H. F
ISCHER
, 1896) and northern SASC
(this study), 677–1500 m.
Remarks: The species can be identified
by its depressed outline, strong umbilical
cords (Figs. 34A,C,F), weak supra-periph-
eral spiral ridge (Figs. 34B, D-E), and dark
brown periostracum. Moelleriopsis messa-
nensis (Seguenza, 1876) is somewhat more
raised and has a different protoconch
(R
OMANI
& B
OGI
, 2016). Moelleriopsis
normani (Figs. 35A-C) is more flattened
and has weak cordlets in the umbilical
area and on the whorl surface.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
41
Figure 35. Moelleriopsis normani (Dautzenberg & H. Fischer, 1897). A-C: Plato Seamount –
SMT2/DW250.H 0.6 mm, W 1.6 mm; D: apical view of protoconch W 0.37 mm; E: basal view
of protoconch.
Figura 35. Moelleriopsis normani (Dautzenberg y H. Fischer, 1897). A-C: Banco Plato -
SMT2/DW250, 0,6 mm alto, 1,6 mm ancho; D: vista apical de la protoconcha, 0,37 mm ancho; E:
vista basal de la protoconcha.
Moelleriopsis normani (Dautzenberg & H. Fischer, 1897) (Fig. 35)
Cyclostrema normani Dautzenberg & H. Fischer, 1897: 175-176, pl. 4 figs. 9-11
Material examined: Azores, Mar da Prata • 1 shell; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018;
M151/23168; grab. Azores, Açor Bank • 2 shells; 38.156°N, 29.084°W; 339 m; 13 Oct. 2018; M151/23139;
grab. Plato Seamount • 25 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242;
dredge. • 1 shell; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
Distribution: Azores (D
AUTZENBERG
& H. F
ISCHER
, 1897: 175; this study)
and Plato Seamount (this study), 952-
1846 m.
Remarks: The species can be identified
by its nearly planispiral outline (Figs. 35A-
C). All other NE Atlantic taxa in Moelleri-
opsis have a slightly raised spire.
Tyro Seamount • 27 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge.
Plato Seamount• 175 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
A
BC
DE
100 µm 100 µm
Holotype, an empty shell (Fig. 37A):
Small (H 1.1 mm, W 1.5 mm) fragile
shell with a flattened apex, irregularly
growing spire, whorls nearly circular in
section, with spiral cordlets, deep
suture, translucent white.
Protoconch: Simple nucleus, ¾
whorls, with somewhat rough surface,
orthocline sharp lip, flexuous, some-
what flaring with thin rim, W 0.24 mm
(Fig. 37D from paratype 2). Transition to
teleoconch clear by change in sharp lip
(Fig. 37D).
Teleoconch: two inflated whorls
with circular cross-section and several
clear growth lines, flat apex with
descending body whorl.
First whorl flush with protoconch,
first ¼ whorl with one faint cordlet, next
½ whorl with a second cordlet close
above the first. Following ¼ whorl with
third cordlet close below first. Second
(body) whorl, first ½ whorl smooth with
three supraperipheral cordlets, fine
growth lines, oblique yet straight at 10°
with spire axis; whorl descending in last
½ whorl well below periphery of penul-
timate whorl. Base with eight fine spiral
cordlets in the umbilical area; umbilicus
deep and open (Fig. 37B of paratype 1).
Aperture 65% of spire height with
nearly circular, slightly prosocline,
rounded lip straightened on with pari-
etal area and slightly angular at the
union with penultimate whorl. Outer lip
blunt, somewhat bevelled inside, col-
umellar lip sharp. Inside smooth.
Variability: Variability of outline is
low; the number and frequency of
growth scars and the strength of spiral
cords on the base is variable.
Distribution: SASC and Azores,
280–811 m.
Remarks: Moelleriopsis messanensis
(Seguenza G., 1876) and M. richardi
(Dautzenberg & Fischer H., 1896) have a
raised apex and strong umbilical cords
whereas M. atlantis n. sp. has a
depressed apex and weak umbilical
cordlets. Moelleriopsis normani (Dautzen-
berg & H. Fischer, 1897) has a nearly
planispiral spire. “Cyclostrema” sykesi
Dautzenberg & Fischer, 1897 is larger,
with a higher spire and it has more
regular and stronger spiral cordlets api-
cally and in the umbilical area.
Iberus, 38 (Suplemento 9), 2020
42
Moelleriopsis atlantis n. sp. (Figs. 36, 37)
Type material: Holotype, Atlantis Seamount• 1 shell (Fig. 37A); 33.971°N, 30.206°W; 677 m; 21 Oct.
2018; M151/23404; grab, in coarse bioclastic sand with coral rubble, live hydrozoans and sponges;
MNHN-IM-2000-35672. Paratypes: • 4 shells (Figs. 37B-D); same data as for holotype; MNHN-IM-
2000-35673, • 5 shells; same data as for holotype; SMF 351098.
Other material examined: Azores, Mar da Prata• 2 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. Atlantis Seamount • 230 shells; 34.082°N, 30.255°W; 335–340 m; 02 Feb. 1993;
SMT2/DW255; dredge. • 10 shells; 34.432°N, 30.542°W; 610–655 m; 03 Feb. 1993; SMT2/DW263;
dredge. • 23 shells; 34.080°N, 30.248°W; 330 m; 04 Feb. 1993; SMT2/TS270; suprabenthic sled. • 70 shells;
34.086°N, 30.226°W; 280 m; 05 Feb. 1993; SMT2/DW274; dredge. • 10 shells; 33.996°N, 30.177°W;
617 m; 21 Oct. 2018; M151/23408; grab. Tyro Seamount • 74 shells; 33.963°N, 28.373°W; 890–925 m; 06
Feb. 1993; SMT2/DW278; dredge. Plato Seamount • 40 shells; 33.197°N, 28.949°W; 690–710 m; 31
Jan. 1993; SMT2/DW242; dredge. Great Meteor Seamount • 2 shells; 29.816°N, 28.433°W; 299 m; 19
Mar. 2010; POS397/106-1; grab. • 1 shell; 29.816°N, 28.433°W; 300 m; 19 Mar. 2010; POS397/106-2; grab.
• 1 shell; 29.750°N, 28.466°W; 292 m; 21 Mar. 2010; POS397/111-2; grab. • 1 shell; 29.683°N, 28.434°W;
289 m; 21 Mar. 2010; POS397/114-7; grab. • 1 shell; 29.565°N, 28.339°W; 948 m; 25 Oct. 2018;
M151/23425-R1; ROV sample. • 2 shells; 29.565°N, 28.332°W; 945 m; 25 Oct. 2018; M151/23425-R4; ROV
sample. • 1 shell; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample. • 6 shells;
29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. • 1 shell; 30.086°N, 28.726°W;
906 m; 26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Seamount • 2 shells; 29.654°N,
29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 18 shells; 29.654°N, 29.015°W; 852 m;
27 Oct. 2018; M151/23436; grab. • 7 shells; 29.654°N, 29.014°W; 811 m; 27 Oct. 2018; M151/23437;
grab. • 1 shell; 29.655°N, 29.004°W; 464 m; 27 Oct. 2018; M151/23438; grab.
Type locality: Atlantis Seamount – 33.971°N – 30.206°W, 677 m.
Etymology: atlantis refers to the type locality, the Atlantis Seamount.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
43
Figure 36. Moelleriopsis atlantis n. sp. A: Atlantis Seamount – M151/23404, holotype, apertural
view, H 1.1 mm; B: paratype 2, apical view of smooth protoconch, W 0.24 mm.
Figura 36. Moelleriopsis atlantis n. sp. A: Banco Atlantis - M151/23404, holotipo, vista apertural,
1,1 mm alto; B: paratipo 2, vista apical de la protoconcha lisa, 0,24 mm ancho.
Figure 37. Moelleriopsis atlantis n. sp. A: Atlantis Seamount – M151/23404, holotype, H 1.1 mm,
W 1.5 mm; B: same locality, paratype 1, W 1.5 mm; C: same locality, paratype 2 in apical view;
D: protoconch W 0.24 mm, same as C; E-G: Plato Seamount – SMT2/DW242, H 1.2 mm, W
2.0 mm; H: protoconch W 0.22 mm, same as G.
Figura 37. Moelleriopsis atlantis n. sp. A: Banco Atlantis - M151/23404. A: holotipo, 1,1 mm alto,
1,5 mm ancho; B: paratipo 1, 1,5 mm ancho; C: paratipo 2, vista apical; D: protoconcha 0,24 mm
ancho, misma que C; E-G: Banco Plato - SMT2/DW242, 1,2 mm alto, 2,0 mm ancho; H: protocon-
cha 0,22 mm ancho, misma que G.
100 µm
AB
500 µm
A
BC
D
EF
H
G
100 µm 100 µm
Holotype, an empty shell (Figs. 39A-D):
Small (H 2.3 mm, W 2.6 mm), moder-
ately solid shell with a flattened apex,
cyrtoconoid outline with convex whorls,
strong spiral carinae, white shell.
Protoconch: ½ whorls, smooth with
fine irregular spiral striae, convex sharp
lip, W 0.32 mm. Transition to teleoconch
clear by change in sculpture (Fig. 39D).
Teleoconch: 2 ½ rounded whorls,
suture shallow.
First whorl flush with protoconch, with
one thick, smoothly rounded cord on the
shoulder. Surface smooth with numerous
fine growth lines and three growth marks
with thickened line. Microsculpture with
numerous rounded shallow pits, pit diam-
eter about 1 µm. Remaining 1 ½ whorls
descending, spiral cord sharper forming
a keel. Microsculpture as in first whorl.
Base of body whorl with two strong
spiral cords, widely spaced, one outside
and one in the umbilical area. Umbilicus
open, deep, tortuous, partly covered by
columellar callus. Inside smooth with
fine growth lines.
Iberus, 38 (Suplemento 9), 2020
44
Figure 38. Moelleriopsis gritta Hoffman n. sp. A: Plato Seamount – SMT2/DW242, holotype,
apertural view, H 2.3 mm; B: Atlantis Seamount – M151/23404, apical view of protoconch with
fine spiral striae, W 0.32 mm, followed by initial teleoconch with supraperipheral cord.
Figura 38. Moelleriopsis gritta Hoffman n. sp. A: Banco Plato - SMT2/DW242, holotipo, vista aper-
tural, 2,3 mm alto; B: Banco Atlantis - M151/23404, vista apical de la protoconcha con estrías espira-
les finas, 0,32 mm ancho, seguida del inicio de la teleoconcha con cordón supraperiférico.
Moelleriopsis gritta Hoffman n. sp. (Figs. 38, 39)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 39A-D); 33.197°N, 28.949°W; 690–710 m;
31 Jan. 1993; SMT2/DW242; dredge, in bioclastic sand with live and dead corals and live sponges;
MNHN-IM-2000-35674. Paratypes: • 1 shell (Figs. 39E-F); same data as for holotype; MNHN-IM-
2000-35675. • 14 shells; same data as for holotype; MNHN-IM-2000-35675.
Other material examined: Azores, Mar da Prata • 8 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. • 6 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab. • 1 shell;
37.659°N, 25.789°W; 599 m; 19 Oct. 2018; M151/23181; box core. Atlantis Seamount • 9 shells (Figs.
39G-I); 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. • 5 shells; 33.996°N, 30.177°W;
617 m; 21 Oct. 2018; M151/23408; grab. Great Meteor Seamount • 1 shell; 30.084°N, 28.500°W; 309
m; 17 Mar. 2010; POS397/98-1; grab. • 1 shell; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-
R6; ROV sample. Little Meteor Seamount • 5 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018;
M151/23436; grab. • 1 shell; 29.655°N, 29.004°W; 464 m; 27 Oct. 2018; M151/23438; grab. • 1 shell;
29.645°N, 28.975°W; 284 m; 27 Oct. 2018; M151/23440; grab.
Type locality: Plato Seamount – 33.197°N – 28.949°W, 690–710 m.
Etymology: named after Gritta Veit-Köhler, marine biologist and partner of the first author, for her
support in the studies.
200 µm
AB
1 mm
Aperture 65% of shell height, near cir-
cular with convex indent along parietal
side, angular (ca. 90°) at union of outer lip
to penultimate whorl. Peristome thick and
rounded, outer lip prosocline at 20° with
spire axis, opening nearly flat. Columella
thin and curved. Callus thick and smooth
with thickened rim on inside columellar
lip, inside of whorl smooth.
Variability: Height up to 2.3 mm.
The thin umbilical cord inside the
umbilicus may be faint or occasionally
lacking.
Distribution: SASC and Azores,
309–944 m.
Remarks: The placement in the genus
Moelleriopsis is based on the protoconch
and the spiral cords in the umbilicus
and on the presence of a shoulder. The
new species is morphologically similar
to the type species Moelleriopsis abyssi-
cola.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
45
Figure 39. Moelleriopsis gritta Hoffman n. sp. A-C: Plato Seamount – SMT2/DW242, holotype,
H 2.3 mm, W 2.8 mm; D: protoconch of the holotype, W 0.31 mm; E: paratype W 2.6 mm; F:
microsculpture, same as E; G-I: Atlantis Seamount – M151/23404, H 2.3 mm, W 2.6 mm; I:
protoconch W 0.32 mm.
Figura 39. Moelleriopsis gritta Hoffman n. sp. A-C: Banco Plato - SMT2/DW242, holotipo, 2,3 mm
alto, 2,8 mm ancho; D: protoconcha del holotipo, 0,31 mm ancho; E: paratipo 2,6 mm ancho; F:
microescultura, misma que E; G-I Banco Atlantis - M151/23404, 2,3 mm alto, 2,6 mm ancho; proto-
concha 0,32 mm ancho.
A
B
C
DE
F
HI
G
100 µm 100 µm
100 µm
Holotype, an empty shell (Figs. 41A-B):
Small (H 1.5 mm, W 1.7 mm) fragile
shell with a cyrtoconoid outline and
flattened apex, irregularly growing
spire, rounded whorls, deep suture,
translucent white.
Protoconch: Simple nucleus, 0.6
whorls, smooth background with three
spiral cordlets, convex sharp lip, W 0.30
mm. Transition to teleoconch clear by
change in sculpture (Fig. 41E of
paratype 2).
Teleoconch: two inflated whorls
with circular cross-section and several
clear growth lines.
First whorl, first ¼ whorl rough
frosted sculpture, ending with sharp
growth scar; following ¾ whorl with
fine frosted sculpture with fine micro-
scopic pits; last ¼ whorl descending
towards periphery of protoconch whorl.
Second (body) whorl with several
growth scars, fine growth lines, oblique
yet straight at 10° with spire axis; whorl
descending well below periphery of
penultimate whorl. Base with eight fine
spiral threads below periphery and four
spiral cords surrounding the wide open
and deep umbilicus (Fig. 32C of
paratype 1). Smooth apparently but
microsculpture irregularly pitted, pit
size 0.5–1.5 µm (Fig. 41B).
Aperture 50% of spire height with
nearly circular, slightly prosocline, com-
Iberus, 38 (Suplemento 9), 2020
46
Moelleriopsis meteorminora n. sp. (Figs. 40, 41)
Type material: Holotype, Little Meteor Seamount • 1 shell (Figs. 41A-B); 29.655°N, 29.004°W; 464
m; 27 Oct. 2018; M151/23438; grab, in coarse bioclastic sand with coral rubble; MNHN-IM-2000-
35677. Paratypes: • 2 shells (Paratypes 1 and 2, Figs. 41C-E); same data as for holotype; MNHN-
IM-2000-35678; • 4 shells; same data as for holotype; SMF 351099.
Other material examined: Great Meteor Seamount • 1 shell; 29.750°N, 28.533°W; 319 m; 24 Oct.
2018; M151/23419; grab. • 1 shell; 30.084°N, 28.566°W; 301 m; 15 Mar. 2010; POS397/92-2; grab. •
1 shell; 30.017°N, 28.533°W; 288 m; 16 Mar. 2010; POS397/95-6; grab. • 1 shell; 29.683°N, 28.434°W;
289 m; 21 Mar. 2010; POS397/114-6; grab. • 3 shells; 29.683°N, 28.434°W; 289 m; 21 Mar. 2010;
POS397/114-7; grab. Little Meteor Seamount • 9 shells; 29.645°N, 28.975°W; 284 m; 27 Oct. 2018;
M151/23440; grab. • 4 shells; 29.633°N, 28.967°W; 282 m; 27 Oct. 2018; M151/23441; grab..
Type locality: Little Meteor Seamount – 29.655°N – 29.004°W, 464 m.
Etymology: meteorminora refers to the type locality; Little Meteor Seamount.
Figure 40. Moelleriopsis meteorminora n. sp. A: Little Meteor Seamount – M151/23438, holotype,
apertural view, H 1.5 mm; B: paratype 2, apical view of protoconch showing three spiral cordlets,
W 0.30 mm, followed by a finely pitted teleoconch.
Figura 40. Moelleriopsis meteorminora n. sp. A: Pequeño Banco Meteor - M151/23438, holotipo,
vista apertural, 1,5 mm alto; B: paratipo 2, vista apical de la protoconcha mostrando tres cordones espi-
rales, 0,30 mm ancho, seguida de una teleoconcha con diminutas punturas.
200 µm
AB
500 µm
plete peristome with rounded outline
with concave bulge on parietal side
(Figs. 41A,C). Suture deep, aligned with
surface penultimate whorl (Fig. 41A).
Inner lip with raised edge (likely coinci-
dent with edge of operculum), inside
smooth (Fig. 41A).
Variability: Variability of outline is
low; the number and frequency of
growth scars and the strength of spiral
threads and cords on the base is variable.
Distribution: SASC, Little- and Great
Meteor Seamounts, 282–464 m.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
47
Figure 41. Moelleriopsis meteorminora n. sp. A: Little Meteor Seamount – M151/23438, holotype,
apertural view, H 1.5 mm, W 1.7 mm; B: microsculpture of the holotype; C: paratype 1, same
locality, basal view, W 1.5 mm; D: paratype 2, same locality, apical view, W 1.7 mm; E: proto-
conch W 0.30 mm, same as D.
Figura 41. Moelleriopsis meteorminora n. sp. A: Pequeño Banco Meteor - M151/23438, holotipo,
vista apertural, 1,5 mm alto, 1,7 mm ancho; B: microescultura del holotipo; C: paratipo 1, misma loca-
lidad, vista basal, 1,5 mm ancho; D: paratipo 2, misma localidad, vista apical, 1,7 mm ancho, proto-
concha 0,30 mm ancho, misma que D.
Genus Xyloskenea B.A. Marshall, 1988
Type taxon: Xyloskenea costulifera B.A. Marshall, 1988 by original designation, off New Zealand.
M
ARSHALL
(1988) originally placed
Xyloskenea in Skeneidae (Trochoidea), but
K
ANO ET AL
. (2009) included it in Seguen-
Remarks: The placement in the genus
Moelleriopsis is based on the protoconch
and the spiral cords in the umbilical
area.
Moelleriopsis normani has a nearly
planispiral outline, and Moelleriopsis
sykesi has stronger umbilical cords and it
is more depressed than M. meteorminora.
Moelleriopsis messanensis from off the
continental margins of SW Europe and
NW Africa has a more depressed outline
and has more and stronger umbilical
cords.
zioidea without an assigned family. The
shell of the type taxon (see W
ARÉN
&
B
OUCHET
1993: 29) is characterised by an
A
B
C
D
E100 µm
100 µm
inflated spire with a flattened apex, an
open umbilicus with strong spiralling keel
that ends on the columella. The protoconch
is sculptured with spiral cords. The initial
teleoconch has several strong axial ribs.
Eight species are currently known
worldwide (M
OLLUSCA
B
ASE
, 2020). The
most important review on Xyloskenea
was provided by M
ARSHALL
(1988), who
described four species with a similar
shell shape from New Zealand. Two
species were described by D
ALL
(1927)
Iberus, 38 (Suplemento 9), 2020
48
Xyloskenea naticiformis (Jeffreys, 1883) (Fig. 42)
Cithna naticiformis Jeffreys, 1883: 112, pl. 20, fig. 11.
Xyloskenea naticiformis:W
ARÉN
, 1996: 202, figs. 3A-D, 5A-D, 6A-D, 7C.
Material examined: Atlantis Seamount • 1 shell (Figs. 42A-B); 34.082°N, 30.255°W; 335 m; 02 Feb.
1993; SMT2/DW255; dredge. • 8 shells; 34.373°N, 30.463°W; 1190–1340 m; 03 Feb. 1993; SMT2/DW261;
dredge. • 1 shell; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993; SMT2/DW264; dredge. • 5 shells;
33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. Tyro Seamount • 2 shells; 33.963°N,
28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge. Plato Seamount • 2 shells; 33.197°N,
28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. • 12 shells (Figs. 33C-I); 33.210°N,
29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Little Meteor Seamount • 1 shell;
29.654°N, 29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 1 shell; 29.654°N, 29.015°W;
852 m; 27 Oct. 2018; M151/23436; grab.
Distribution: Amphiatlantic, 18–65°N,
677–4862 m (W
ARÉN
, 1996: 202; R
EX ET AL
.,
2002: 218-223; H
OFFMAN ET AL
, 2010: 53;
this study).
Remarks: The shell of X. naticiformis ex-
hibits a wide morphological variability:
within one location we found a gradual
transition from somewhat compressed
specimens with a single keel at the base
of the body whorl to specimens with more
raised and inflated whorls that also have
a supraperipheral angle without really
forming a keel. The form with a basal keel
only has been figured by W
ARÉN
(1996)
whereas specimens with an incipient ad-
ditional keel high on the whorl surface
have been shown by R
EX ET AL
.(2002);
these specimens may be conspecific with
X. naticiformis or alternatively belong to
X. translucens (Dall, 1927).
Xyloskenea translucens (Dall, 1927) (Fig. 43)
Lydiphnis translucens Dall, 1927: 124.
Xyloskenea translucens:R
UBIO ET AL
, 2011: 212, figs. 120A-F.
Material examined: Atlantis Seamount • 55 shells; 34.082°N, 30.255°W; 335–340 m; 02 Feb. 1993;
SMT2/DW255; dredge. • 2 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. • 1
shell; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Plato Seamount • 25 shells;
33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. Great Meteor Seamount • 1
shell; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample.
Distribution: off Georgia, U.S.A. (D
ALL
,
1927; R
UBIO ET AL
, 2011), SASC (this study),
Lusitanian banks and seamounts (H
OFF
-
MAN
& F
REIWALD
, 2017: 68, figs. 37-40 as
Trenchia biangulata Rubio & Rolán, 2013).
Amphiatlantic, 29.5–34.1°N, 335–1050 m.
from the NW Atlantic and subsequently
placed in Xyloskenea (R
UBIO ET AL
., 2011:
212): one originally in Tornidae (Lydiph-
nis translucens), and one in Vitrinellidae
(Vitrinella rhyssa). J
EFFREYS
(1883)
described Cithna naticiformis from the
NE Atlantic and W
ARÉN
(1996)
redescribed this taxon and transferred it
to Xyloskenea. H
OFFMAN ET AL
. (2010)
described Xyloskenea xenos from the
Hatton Bank, but this taxon is here
transferred to Trenchia (see below).
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
49
Figure 42. Xyloskenea naticiformis (Jeffreys, 1883). A: Atlantis Seamount – SMT2/DW255, H 1.4
mm, W 1.6 mm; B: protoconch W 0.26 mm, same shell as A; C-E: Plato Seamount –
SMT2/DW250, H 1.5 mm, W 1.9 mm; F: protoconch W 0.25 mm, same as E; G: same locality,
W 1.8 mm; H: same locality, W 1.6 mm; I: protoconch W 0.25 mm, same as H.
Figura 42. Xyloskenea naticiformis (Jeffreys, 1883). A: Banco Atlantis - SMT2/DW255, 1,4 mm alto,
1,6 mm ancho; B: protoconcha 0,26 mm ancho, misma que A; C-E: Banco Plato - SMT2/DW250, 1,5
mm alto, 1,9 mm ancho; F: protoconcha 0,25 mm ancho, misma que E; G: misma localidad, 1,8 mm
ancho; H: misma localidad, 1,6 mm ancho; I: protoconcha 0,25 mm ancho, misma que H.
Remarks: Trenchia biangulata Rubio &
Rolán, 2013 is similar in having two
keels but has a smooth protoconch. The
specimens reported by H
OFFMAN
&
F
REIWALD
(2017: figs. 37-40 as Trenchia
biangulata) from the Coral Patch
Seamount show three cordlets on the
protoconch, therefore belong to Xyloske-
nea translucens as shown by R
UBIO ET AL
.
(2011: 212, USNM108434). The speci-
mens found in this study (Figs. 43C, G)
also show the spiral cordlets and are
considered conspecific to Xyloskenea
translucens.
Genus Trenchia Knudsen, 1964
Type taxon: Trenchia wolffi Knudsen, 1964 by original designation, Kermadec Trench, 5850–6730 m.
K
ANO ET AL
. (2009) included the
genus in Seguenzioidea without an
assigned family.
K
NUDSEN
(1964) provided a brief
diagnosis for the genus: a small conical
shell, a relatively large aperture, a thin
A
B
CDE
F
H
I
G
100 µm
100 µm 100 µm
horny operculum and a rhipidoglossate
radula with two lateral teeth and
numerous marginal teeth. The type
species has a smooth protoconch, diam-
eter 0.35 mm. The teleoconch has one
cord on the upper whorl surface, one
below the periphery and a sharp keel in
the umbilicus. Compared to Xyloskenea,
species of Trenchia have a similar shell
and radula but differ essentially in
having a smooth and featureless proto-
conch, (W
ARÉN
& B
OUCHET
1993).
R
UBIO
& R
OLÁN
(2013) described two
species: Trenchia anselmoi from the Alboran
Sea and T. biangulata from Galicia Bank
and the Canaries. Xyloskenea xenos
Hoffman, van Heugten & Lavaleye, 2010
is transferred herein to the genus Trenchia.
Iberus, 38 (Suplemento 9), 2020
50
Trenchia xenos (Hoffman, van Heugten & Lavaleye, 2010) comb. nov. (Fig. 44)
Xyloskenea xenos Hoffman, van Heugten & Lavaleye, 2010: 53-54, figs. 28-33.
Material examined: Azores, Mar da Prata • 1 shell; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. Atlantis Seamount • 53 shells; 34.373°N, 30.463°W; 1190–1340 m; 03 Feb. 1993;
SMT2/DW261; dredge. • 9 shells; 34.432°N, 30.542°W; 610–655 m; 03 Feb. 1993; SMT2/DW263;
dredge. • 2 shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993; SMT2/DW264; dredge. • 28 shells
(Figs. 44A-D); 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. Tyro Seamount • 1 shell;
33.998°N, 28.343°W; 945–1000 m; 06 Feb. 1995; SMT2/DW277; dredge. • 39 shells (Figs. 44F-I);
33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge. Plato Seamount • 4 shells;
Figure 43. Xyloskenea translucens (Dall, 1927). A, B: Atlantis Seamount – M151/23408, H 1.4
mm, W 1.6 mm; C: protoconch W 0.26 mm, same as B; D, E: same locality, H 1.5 mm, W 1.9
mm; F: detail of umbilicus, same as D; G: protoconch W 0.25 mm, same as D.
Figura 43. Xyloskenea translucens (Dall, 1927). A, B: Banco Atlantis - M151/23408, 1,4 mm alto,
1,6 mm ancho; C: protoconcha 0,26 mm ancho, misma que B; D, E: misma localidad, 1,5 mm alto,
1,9 mm ancho; F: detalle del ombligo. misma que D; G: protoconcha 0,25 mm ancho, misma que D.
A
B
C
D
E
F
G
100 µm
100 µm
100 µm
33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. • 13 shells (Fig. 44E); 33.210°N,
29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Great Meteor Seamount • 1 shell;
29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample. • 1 shell; 29.568°N, 28.339°W;
855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. Little Meteor Seamount •12 shells; 29.654°N,
29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
the original description, which should
be W 0.20-0.28 mm (Figs. 44C, F).
The smooth protoconchs of speci-
mens from the SASC fit Trenchia rather
than Xyloskenea whose protoconch has a
spiral cord sculpture (M
ARSHALL
, 1988;
B
OUCHET
& W
ARÉN
, 1993; R
UBIO ET AL
.,
2011).
M
C
L
EAN
(1992: 275) reviewed the
similar genus Choristella Bush 1892, which
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
51
Figure 44. Trenchia xenos (Hoffman, van Heugten & Lavaleye, 2010). A, B: Atlantis Seamount –
M151/23404, H 3.1 mm, W 4.1 mm; C: same locality, W 1.5 mm; D: protoconch W 0.20 mm,
same as C; E: Plato Seamount – SMT2/DW250, H 2.4 mm, W 3.1 mm. F: Tyro Seamount –
SMT2/DW278, W 1.8 mm; G: protoconch W 0.28 mm, same as F; H, I: same locality, live-col-
lected specimen, H 1.6 mm, W 2.2 mm.
Figura 44. Trenchia xenos (Hoffman, van Heugten y Lavaleye, 2010). A, B: Banco Atlantis -
M151/23404, 3.1 mm alto, 4,1 mm ancho; C: misma localidad, 1,5 mm ancho; D: protoconcha 0,20
mm ancho, misma que C; E: Banco Plato - SMT2/DW250, 2,4 mm alto, 3.1 mm ancho. F: Banco
Tyro - SMT2/DW278, 1,8 mm ancho; G:protoconcha 0,28 mm ancho, misma que F; H, I: misma
localidad, ejemplar recogido vivo, 1,6 mm alto, 2,2 mm ancho.
Distribution: Hatton Bank (H
OFFMAN
ET AL
., 2010), Azores and SASC (this
study), 340–1340 m.
Remarks: The morphology of the
shell is variable; some specimens have a
flat apex (Figs. 35D, G), others are more
raised (Fig. 35E). Trenchia xenos has a
smooth protoconch, ¾ whorl; R
UBIO
&
R
OLÁN
(2013) indicated an error with
the reported size of the protoconch in
A
B
CD
E
F
H
I
G
100 µm
100 µm
has a smooth protoconch, a complete peri-
stome, a deep suture and an umbilical keel.
Most species in Choristella have a raised
spire with 2–3 smooth inflated whorls like
for example Choristella nofronii McLean,
1992 from the Alboran Sea (M
C
L
EAN
, 1992:
281-282, fig. 16). C. ponderi McLean, 1992
from Australia has a flattened spire as our
species. W
ARÉN
(1996: 202) suggested a
Iberus, 38 (Suplemento 9), 2020
52
Trenchia biangulata Rubio & Rolán, 2013 (Fig. 45)
Trenchia biangulata Rubio & Rolán, 2013: 2-4, figs. 1-6.
Material examined: Atlantis Seamount • 2 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018;
M151/23404; grab. • 1 shell; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab.
Distribution: Galicia Bank, Canary
and Salvage Islands (R
UBIO
& R
OLÁN
,
2013), Coral Patch Seamount (H
OFFMAN
& F
REIWALD
, 2017) and Atlantis
Seamount (this study), 400–1000 m.
Shells reported as Trenchia sp. from the
Sedlo, Seine and Ampère Seamounts by
B
ECK ET AL
.(2006) cannot be conclu-
sively be identified as belonging to this
species or to Xyloskenea translucens, since
the image of the protoconch is unclear.
Remarks: Xyloskenea translucens has a
protoconch sculpture with spiral cords
and the spire is slightly more raised.
Trenchia biangulata has a smooth proto-
conch sculpture.
granular sculpture of the nucleus; this
character is not present in our species.
We move Xyloskenea xenos to the genus
Trenchia to be consistent with the mor-
phological assignment of the European
species Trenchia anselmoi Rubio & Rolán,
1993 and Trenchia biangulata Rubio & Rolán,
1993, both with a smooth protoconch and
flattened outline.
Figure 45. Trenchia biangulata Rubio & Rolán, 2013. A-C: Atlantis Seamount – M151/23404, H
1.5 mm, W 2.5 mm; D: protoconch W 0.26 mm; E: Atlantis Seamount – M151/23408, W 2.3
mm; F: protoconch W 0.22 mm.
Figura 45. Trenchia biangulata Rubio & Rolán, 2013. A-C: Banco Atlantis – M151/23404, 1,5 mm
ancho, 2,5 mm ancho; D: protoconcha 0,26 mm ancho; E: Banco Atlantis– M151/23408, 2,3 mm
ancho; F: protoconcha 0,22 mm ancho.
A
BC
DEF
100 µm 100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
53
Figure 46. Trenchia teriuga n. sp. A: Tyro Seamount – SMT2/DW278, holotype, apertural view, H
1.4 mm; B: Atlantis Seamount – M151/23404, apical view of smooth protoconch with flexuous
lip, W 0.26 mm.
Figura 46. Trenchia teriuga n. sp. A: Tyro Seamount - SMT2/DW278, holotipo, vista apertural, 1,4 mm alto;
B: Atlantis Seamount - M151/23404, vista apical de la protoconcha liso con un borde flexuoso, 0,26 mm ancho.
Trenchia teriuga n. sp. (Figs. 46, 47)
Type material: Holotype, Tyro Seamount • 1 shell (Figs. 47A-D); 33.963°N, 28.373°W; 890–925 m;
06 Feb. 1993; SMT2/DW278; dredge, in sediment with live and dead corals, live sponges, brachio-
pods, echinoderms and crustaceans; MNHN-IM-2000-35679. Paratypes: • 2 shells (Figs. 47E-F, G);
same data as for holotype; MNHN-IM-2000-35680. • 125 shells; same data as for holotype; MNHN-
IM-2000-35681.
Other material examined: Azores, Mar da Prata • 1 shell; 37.666°N, 25.966°W; 961 m; 09 Oct. 2018;
M151/23121; grab. • 1 shell; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018; M151/23168; grab. Atlantis
Seamount •40 shells; 34.373°N, 30.463°W; 1190–1340 m; 03 Feb. 1993; SMT2/DW261; dredge. • 6
shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993; SMT2/DW264; dredge. • 18 shells (Figs. 47H-
L); 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. Plato Seamount • 4 shells; 33.197°N,
28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. • 22 shells; 33.210°N, 29.287°W; 1450–1500
m; 01 Feb. 1993; SMT2/DW250; dredge. • Great Meteor Seamount • 1 shell; 29.565°N, 28.339°W;
948 m; 25 Oct. 2018; M151/23425-R1; ROV sample. • 2 shells; 29.565°N, 28.339°W; 944 m; 25 Oct.
2018; M151/23425-R6; ROV sample. • 2 shells; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-
R9; ROV sample. • 1 shell; 30.086°N, 28.726°W; 906 m; 26 Oct. 2018; M151/23429-R8; ROV sample.
Little Meteor Seamount •13 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
Type locality: Tyro Seamount – 33.963°N – 28.373°W, 890–925 m.
Etymology: teriuga (Latin: ter iuga) refers to the three ridges (cords) on the body whorl.
Holotype, an empty shell (Figs. 47A-D):
Small (H 1.4 mm, W 2.3 mm) solid shell
with a flat, regularly growing spire,
with three sharp spiral keels, white.
Protoconch: Simple nucleus, ¾
whorls, smooth, flexuous sharp lip,
somewhat flaring, W 0.26 mm. Transi-
tion to teleoconch clear by change in
sculpture (Fig. 47D of holotype, Fig. 47F
of paratype).
Teleoconch: 2 ¼ rounded whorls, all
whorls moderately convex, suprape-
ripheral spiral cord forming a weak
keel. Peripheral cord visible only on the
last whorl, but determines a channel
above suture on previous whorls. Suture
deeply impressed.
First whorl flush with protoconch,
numerous fine growth lines with a few
growth scars. Second whorl (in part
body whorl) with strong second cord at
periphery, smooth and rounded. Whorl
surface sloping above top spiral cord,
convex below. Numerous growth lines,
prosocline. The upper cord fades on the
body whorl.
Base of body whorl (second whorl
and ¼ of third whorl) with third spiral
cord, forming a keel, whorl flattened
above and below towards umbilicus.
100 µm
A
B
500 µm
Iberus, 38 (Suplemento 9), 2020
54
Figure 47. Trenchia teriuga n. sp. A-C: Tyro Seamount – SMT2/DW278, holotype, H 1.4 mm, W
2.3 mm; D: protoconch of the holotype W 0.26 mm; E: Paratype 1, same locality, W 2.3 mm; F:
protoconch W 0.26 mm, same as E; G: paratype 2, same locality, H 1.3 mm, W 2.2 mm. H:
Atlantis Seamount – M151/23404, W 1.9 mm; I: same locality, W 2.0 mm; J: protoconch W 0.26
mm, same as I; K, L: same locality, H 1.3 mm, W 2.1 mm.
Figura 47. Trenchia teriuga n. sp. A-C: Banco Tyro – SMT2/DW278, holotipo, 1,4 mm alto, 2,3 mm
ancho; D: protoconcha del holotipo 0,26 mm ancho; E: paratipo 1, misma localidad, 2,3 mm ancho; F:
protoconcha 0,26 mm ancho, misma que E; G: paratipo 2, misma localidad, 1,3 mm alto, 2,2 mm
ancho; H: Banco Atlantis – M151/23404, 1,9 mm ancho; I: misma localidad, 2,0 mm ancho; J: pro-
toconcha 0,26 mm ancho, misma que I; K, L: misma localidad, 1,3 mm alto, 2,1 mm ancho.
Umbilicus wide and open, demarcated
by another sharp keel running from base
of columella and spiralling inside. Inside
umbilicus, numerous growth lines.
Aperture 75% of shell height,
oblong, angular (90°) at union with
penultimate whorl. Columellar lip
sharp, protruding at its base to cover
A
B
C
D
EF
H
I
G
J
K
L
100 µm
100 µm
100 µm
umbilical keel. Outer lip sharp, proso-
cline. Columellar and parietal callus
smooth, thinning on parietal side, inside
of whorl smooth. Angle of union with
penultimate whorl about 90°.
Variability: The upper cord is occa-
sionally absent, or only weakly present
on the initial teleoconch. The peripheral
and base cords are always present.
Width up to 2.5 mm.
Distribution: SASC, Azores, 677–1500
m.
Remarks: This species is placed in the
genus Trenchia based on the smooth pro-
toconch. B
ECK ET AL
. (2006) illustrated as
Circulus supranitidus (Wood, 1848) a
shell from the Sedlo Seamount which
we believe to be Trenchia teriuga n. sp.
Circulus has a wide umbilicus with
several spiral cords and a strongly
prosocline lip, whereas Trenchia has its
umbilicus partly covered and has a
sharp umbilical keel.
Lydiphnis hendersoni Dall, 1927 is a
very similar species but has a distinctly
protruding peripheral keel with a flat
upper and lower side (R
UBIO ET AL
.,
2011: 93-95, figs. 48A-F as Cyclostremis-
cus hendersoni placed in Tornidae), and it
has a tenuous spiral microsculpture on
the adapical surface of the last whorl.
The animal of that species is unknown
but its shell has a sharp umbilical keel
similar to species in Xyloskenea or
Trenchia, where it is likely to belong.
Trenchia teriuga is similar to Xyloske-
nea naticiformis (Jeffreys, 1883) and X.
translucens (Dall, 1927), however, these
species lack the peripheral cord and
their protoconchs have a spiral sculp-
ture. Trenchia xenos (Hoffman, van
Heugten & Lavaleye, 2010) has a similar
protoconch but its shell is larger with
inflated whorls and it lacks the spiral
cords. T. biangulata Rubio & Rolán, 2013
lacks the peripheral cord.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
55
Superfamily T
ROCHOIDEA
Rafinesque, 1815
Family S
KENEIDAE
W. Clark, 1851
Genus Cirsonella Angas, 1877
Type taxon: Cirsonella australis Angas, 1877 accepted as Cirsonella weldii (Tenison Woods, 1877),
type by monotypy.
W
ARÉN
(1992) provided a diagnosis
of the shell: small, almost globular and
smooth shell, prosocline aperture,
umbilicus covered by callus. Protoconch
finely and irregularly spirally striated.
Twenty-seven species are known
globally according to M
OLLUSCA
B
ASE
(2020) three of which live in the NE
Atlantic and Mediterranean Sea:
Cirsonella romettensis (Granata, 1877)
from the continental shelves of the
Mediterranean Sea, SW Europe and
NW Africa, and C. ateles (Dautzenberg
& H. Fischer, 1896) and C. gaudryi
(Dautzenberg & H. Fischer, 1896) from
off the Azores.
Cirsonella ateles (Dautzenberg & H. Fischer, 1896) (Fig. 48)
Tharsis ateles Dautzenberg & H. Fischer, 1896: 484, pl. 22 figs. 1-3.
Material examined: Azores, Mar da Prata • 1 shell; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018;
M151/23112; grab. • 2 shells; 37.666°N, 25.966°W; 952 m; 17 Oct. 2018; M151/23168; grab. • 1 shell;
37.659°N, 25.789°W; 599 m; 19 Oct. 2018; M151/23181; box core. Atlantis Seamount • 24 shells;
34.373°N, 30.463°W; 1190–1340 m; 03 Feb. 1993; SMT2/DW261; dredge. • 1 shell; 34.432°N, 30.542°W;
610–655 m; 03 Feb. 1993; SMT2/DW263; dredge. • 40 shells; 34.412°N, 30.513°W; 795–830 m; 03
Feb. 1993; SMT2/DW264; dredge. • 13 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404;
grab. Tyro Seamount • 186 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278;
dredge. Plato Seamount • 9 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242;
dredge. • 492 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Irving
Seamount • 1 shell; 32.143°N, 28.178°W; 1030–1035 m; 28 Jan. 1996; SMT2/DW225; dredge. Hyères
Seamount • 21 shells; 31.425°N, 28.863°W; 950–1250 m; 16 Jan. 1993; SMT2/DW185; dredge. • 675
shells; 31.158°N, 28.725°W; 845–990 m; 19 Jan. 1993; SMT2/DW203; dredge. Great Meteor Seamount
• 4 shells; 30.082°N, 28.730°W; 1032 m; 26 Oct. 2018; M151/23429-R1; ROV sample. • 2 shells;
30.086°N, 28.726°W; 906 m; 26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Seamount •
5 shells; 29.654°N, 29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 56 shells; 29.654°N,
29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab. • 4 shells; 29.645°N, 28.975°W; 284 m; 27 Oct.
2018; M151/23440; grab.
Iberus, 38 (Suplemento 9), 2020
56
Distribution: Azores (D
AUTZENBERG
& H. F
ISCHER
, 1896; this study) and
SASC (this study), 284–2102 m.
Remarks: This species is charac-
terised by a descending body whorl, a
crescent-shaped opening at the umbili-
cus, which is demarcated by a nodular
keel. Occasionally, the umbilicus is fully
closed by a thin transparent callus. Its
umbilical area has 1–3 thin incised lines
(Fig. 48D, visible in juveniles). The
diameter of the protoconch is 0.28–0.30
mm. Cirsonella gaudryi (Dautzenberg &
H. Fischer, 1896) is similar but it has
always a closed umbilicus when adult,
it is smaller and more compact; the
diameter of its protoconch is 0.24–0.25
mm. Adult specimens of Cirsonella
romettensis (Granata, 1877) have a closed
umbilicus; their umbilical area has
strong spiral cordlets and the diameter
of the protoconch is 0.25–0.29 mm.
Most shells from the Azores and the
SASC have fine, incised spiral lines on
the basal part of the body whorl, con-
trary to C. romettensis which is smooth.
We are uncertain whether the mor-
phological differences of the three NE
Atlantic species in Cirsonella are variations
within one species or whether they belong
to two or three species. In this study they
are retained as separate species.
Cirsonella gaudryi (Dautzenberg & H. Fischer, 1896) (Fig. 49)
Tharsis gaudryi Dautzenberg & H. Fischer, 1896: 486, pl. 21 figs. 13-15.
Material examined: Azores, José Gaspar Seamount • 1 live specimen and 7 shells; 37.675°N,
25.717°W; 329 m; 06 Oct. 2018; M151/23105; grab. • 3 shells; 37.675°N, 25.717°W; 311 m; 16 Oct.
2018; M151/23161; box core. Azores, Mar da Prata • 69 shells; 37.673°N, 25.925°W; 595 m; 08 Oct.
2018; M151/23111; grab. • 76 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab.
• 10 shells; 37.601°N, 25.874°W; 190 m; 16 Oct. 2018; M151/23160; grab. • 1 shell; 37.644°N, 25.781°W;
610 m; 16 Oct. 2018; M151/23162; grab. Azores, Açor Bank • 18 shells; 38.156°N, 29.084°W; 339 m;
13 Oct. 2018; M151/23139; grab. Atlantis Seamount • 1665 shells; 34.082°N, 30.255°W; 335–340 m;
02 Feb. 1993; SMT2/DW255; dredge. • 270 shells; 33.997°N, 30.203°W; 420–460 m; 02 Feb. 1993;
SMT2/DW258; dredge. • 19 shells; 34.080°N, 30.248°W; 330 m; 04 Feb. 1993; SMT2/TS270; supra-
benthic sled. • 270 shells; 34.086°N, 30.226°W; 280 m; 05 Feb. 1993; SMT2/DW274; dredge. • 16
shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab. • 82 shells; 33.996°N, 30.177°W;
617 m; 21 Oct. 2018; M151/23408; grab. Tyro Seamount • 1 shell; 33.998°N, 28.343°W; 945–1000 m;
06 Feb. 1995; SMT2/DW277; dredge. Plato Seamount • 3 shells; 33.205°N, 29.032°W; 565 m; 31 Jan.
1993; SMT2/DW240; dredge. • 13 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242;
dredge. • 41 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Irving
Seamount • 2 shells; 32.264°N, 27.531°W; 670–715 m; 30 Jan. 1993; SMT2/DW237; dredge. Hyères
Seamount • 6 shells; 31.499°N, 28.992°W; 300–310 m; 17 Jan. 1994; SMT2/DE188; dredge. • 4 shells;
31.465°N, 28.985°W; 700–750 m; 17 Jan. 1998; SMT2/DW192; dredge. Great Meteor Seamount • 13
live-collected specimens 81 shells; 30.033°N, 28.368°W; 470 m; 11 Jan. 1993; SMT2/DW152; dredge.
• 1 shell; 29.670°N, 28.433°W; 290 m; 13 Jan. 1993; SMT2/TS163; dredge. • 13 shells; 30.040°N,
28.712°W; 620–650 m; 14 Jan. 1993; SMT2/DE174; dredge. • 2 shells; 29.750°N, 28.533°W; 316 m; 14
Mar. 2010; POS397/89-5; grab. • 1 shell; 29.750°N, 28.533°W; 315 m; 14 Mar. 2010; POS397/89-6;
grab. • 1 shell; 29.884°N, 28.601°W; 295 m; 14 Mar. 2010; POS397/90-1; grab. • 2 shells; 30.083°N,
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
57
Figure 48. Cirsonella ateles (Dautzenberg & H. Fischer, 1896). A: Hyères Seamount – SMT2/DW203,
H 2.1 mm, W 2.1 mm; B: same locality, H 2.0, W 2.1 mm; C: umbilical area, same as B; D: same
locality, W 1.8 mm, umbilical view; E: same locality, W 1.6 mm; F: protoconch W 0.28 mm, same
as E; G: Plato Seamount – SMT2/DW250, H 2.0 mm, W 2.3 mm; H: same locality, H 2.6 mm, W
2.6 mm; I: same locality, W 2.5 mm; J: protoconch W 0.30 mm, same as I.
Figura 48. Cirsonella ateles (Dautzenberg & H. Fischer, 1896). A: Banco Hyères – SMT2/DW203,
2,1 mm alto, 2,1 mm ancho; B: misma localidad, H 2,0 mm alto, 2,1 mm ancho; C: area del ombligo,
misma que B; D: misma localidad, 1,8 mm ancho, vista umbilical; E: misma localidad, 1,6 mm
ancho; F: protoconcha 0,28 mm ancho, misma que E; G: Banco Plato – SMT2/DW250, 2,0 mm alto,
2,3 mm ancho; H: misma localidad, 2,6 mm alto, 2,6 mm ancho; I: misma localidad, 2,5 mm ancho;
J: protoconcha 0,30 mm ancho, misma que I.
28.633°W; 310 m; 15 Mar. 2010; POS397/91-10; grab. • 2 shells; 30.083°N, 28.634°W; 311 m; 15 Mar.
2010; POS397/91-11; grab. • 1 shell; 30.084°N, 28.566°W; 301 m; 15 Mar. 2010; POS397/92-2; grab.
• 2 shells; 30.017°N, 28.533°W; 288 m; 16 Mar. 2010; POS397/95-6; grab. • 1 shell; 29.950°N, 28.633°W;
309 m; 17 Mar. 2010; POS397/96-7; grab. • 2 shells; 29.950°N, 28.567°W; 285 m; 19 Mar. 2010;
POS397/98-1; grab. • 1 shell; 29.950°N, 28.567°W; 285 m; 19 Mar. 2010; POS397/98-3; grab. • 2
AB
C
DE
F
H
I
G
J
100 µm
100 µm
100 µm
shells; 29.950°N, 28.567°W; 285 m; 19 Mar. 2010; POS397/102-3; grab. • 1 shell; 29.816°N, 28.433°W;
299 m; 19 Mar. 2010; POS397/106-1; grab. • 4 shells; 29.816°N, 28.433°W; 300 m; 19 Mar. 2010;
POS397/106-2; grab. • 2 shells; 29.816°N, 28.433°W; 300 m; 19 Mar. 2010; POS397/106-3; grab. • 2
shells; 29.817°N, 28.567°W; 308 m; 20 Mar. 2010; POS397/109-7; grab. • 3 shells; 29.750°N, 28.466°W;
291 m; 21 Mar. 2010; POS397/111-1; grab. • 6 shells; 29.750°N, 28.466°W; 292 m; 21 Mar. 2010;
POS397/111-2; grab. • 2 shells; 29.750°N, 28.466°W; 293 m; 21 Mar. 2010; POS397/111-3; grab. • 4
shells; 29.683°N, 28.434°W; 288 m; 21 Mar. 2010; POS397/114-5; grab. • 4 shells; 29.683°N, 28.434°W;
289 m; 21 Mar. 2010; POS397/114-6; grab. • 15 shells; 29.683°N, 28.434°W; 289 m; 21 Mar. 2010;
POS397/114-7; grab. • 18 shells; 29.750°N, 28.533°W; 319 m; 24 Oct. 2018; M151/23419-2; grab. •
2 shells; 29.565°N, 28.339°W; 948 m; 25 Oct. 2018; M151/23425-R1; ROV sample. • 2 shells; 29.565°N,
28.332°W; 945 m; 25 Oct. 2018; M151/23425-R4; ROV sample. • 35 shells; 29.565°N, 28.339°W; 944
m; 25 Oct. 2018; M151/23425-R6; ROV sample. • 39 shells; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018;
M151/23425-R9; ROV sample. Little Meteor Seamount • 34 shells; 29.654°N, 29.015°W; 852 m; 27
Oct. 2018; M151/23436; grab. • 210 shells; 29.655°N, 29.004°W; 464 m; 27 Oct. 2018; M151/23438;
grab. • 22 shells; 29.645°N, 28.975°W; 284 m; 27 Oct. 2018; M151/23440; grab. • 16 shells; 29.633°N,
28.976°W; 282 m; 27 Oct. 2018; M151/23441; grab. • 9 shells; 29.633°N, 28.983°W; 274 m; 27 Oct.
2018; M151/23442; grab.
cordlets or is smooth (H
OFFMAN ET AL
.,
2008, figs. 33J-K). Adult specimens of C.
ateles grow larger with a more descend-
ing body whorl, a larger protoconch
(0.28-0.30 mm versus 0.24-0.25 mm in C.
gaudryi) and the umbilicus has a narrow
crescent-shaped opening in most speci-
mens; most specimens are found deeper
then those of C. gaudryi.
Iberus, 38 (Suplemento 9), 2020
58
Distribution: Azores (D
AUTZENBERG
& H. F
ISCHER
, 1896; this study), SASC
(this study), off western Morocco
(D
AUTZENBERG
, 1927) and Hatton Bank
(H
OFFMAN ET AL
., 2010), 274–2018 m.
Remarks: Cirsonella romettensis
(Granata, 1877) is similar but its umbili-
cal area has strong spiral cords in juve-
niles whereas C. gaudryi has weak
Genus Ganesa Jeffreys, 1883
Type taxon: Ganesa nitidiuscula Jeffreys, 1883, subsequent designation by B
USH
(1897), syntypes
from Donegal Bay, Ireland and off Cape Mondego, Portugal, bathyal.
Three species are known globally:
the type taxon and Ganesa panamensis
Dall, 1881, from off western Central
America, and Ganesa poseidonae
Hoffman & Freiwald, 2018 from off
Mauritania.
Ganesa nitidiuscula Jeffreys, 1883 (Fig. 50)
Ganesa nitidiuscula Jeffreys, 1883: 94, pl. XIX fig. 8.
Ganesa nitidiuscula: W
ARÉN
, 1980: 17; W
ARÉN
, 1991: 176, fig. 33B; H
OFFMAN ET AL
., 2018: 28-29,
figs. 1-12.
Material examined: Azores, Mar da Prata • 43 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. Atlantis Seamount • 17 shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993;
SMT2/DW264; dredge. • 30 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404; grab.
Tyro Seamount • 1 shell; 33.998°N, 28.343°W; 945–1000 m; 06 Feb. 1995; SMT2/DW277; dredge. •
203 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge. Plato Seamount •
5 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993; SMT2/DW242; dredge. Great Meteor Sea-
mount • 1 shell; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. Little
Meteor Seamount• 4 shells; 29.654°N, 29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample.
• 21 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab. • 2 shells; 29.654°N, 29.014°W;
811 m; 27 Oct. 2018; M151/23437; grab.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
59
Figure 49. Cirsonella gaudryi (Dautzenberg & H. Fischer, 1896). A: Atlantis Seamount –
SMT2/DW255, H 1.7 mm, W 1.8 mm; B: protoconch W 0.24 mm, same as A; C, D: Great
Meteor Seamount – SMT2/DW152, H 1.7 mm, W 2.0 mm; E: protoconch W 0.24 mm; F: oper-
culum W 0.90 mm, same specimen as C-D; G: Little Meteor Seamount – M151/23438, H 1.7
mm, W 1.9 mm; H: protoconch W 0.25 mm, same as G; I: Great Meteor Seamount –
POS397/114, H 1.9 mm, W 2.0 mm; J, K: same locality, H 1.3 mm, W 1.5 mm.
Figure 49. Cirsonella gaudryi (Dautzenberg & H. Fischer, 1896). A: Banco Atlantis –
SMT2/DW255, 1,7 mm alto, 1,8 mm ancho; B:protoconcha 0,24 mm ancho, misma que A; C, D:
Gran Banco Meteor – SMT2/DW152, 1,7 mm alto, 2,0 mm ancho; E: protoconcha 0,24 mm ancho;
F: opérculo 0,90 mm ancho, mismo ejemplar que C-D; G: Pequeño Banco Meteor – M151/23438, 1,7
mm alto, 1,9 mm ancho; H: protoconcha 0,25 mm ancho, misma que G; I: Gran Banco Meteor –
POS397/114, 1,9 mm alto, 2,0 mm ancho; J, K: misma localidad, 1,3 mm alto, 1,5 mm ancho.
AB
CD
E
F
H
I
G
JK
100 µm
100 µm 100 µm
Distribution: Known from the Faroes
(Jeffreys, 1883) to Mauritania (H
OFFMAN
ET AL
., 2018) and SASC (this study) in the
NE Atlantic and on the Bahamas Bank in
the NW Atlantic (H
OFFMAN ET AL
., 2018).
Bathymetric range 474–2000 m.
Remarks: This species can easily be
identified by its chaotic cellular sculp-
ture on the protoconch and the near-
vertical rib in the umbilical area
(H
OFFMAN ET AL
., 2018; this study, Figs.
50A-F).
Iberus, 38 (Suplemento 9), 2020
60
Figure 50. Ganesa nitidiuscula Jeffreys, 1883. A: Tyro Seamount – SMT2/DW278, H 2.7 mm, W
2.5 mm; B: detail of umbilical area; C: protoconch W 0.28 mm, same as A; D, E: same locality, H
2.4 mm, W 2.5 mm; F: same locality, W 1.4 mm; G: protoconch W 0.28 mm, same as F.
Figura 50. Ganesa nitidiuscula Jeffreys, 1883. A: Banco Tyro – SMT2/DW278, 2,7 mm alto, 2,5 mm
ancho; B: protoconcha 0,28 mm ancho, misma que A; D, E: misma localidad, 2,4 mm alto, 2,5 mm
ancho; F: misma localidad, 1,4 mm ancho; G: protoconcha 0,28 mm ancho, misma que F.
Genus Lopheliella Hoffman, van Heugten & Lavaleye, 2008
Type taxon: Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008 by original designa-
tion, Rockall Bank.
H
OFFMAN ET AL
. (2008) provided a
diagnosis: adult size 1.8 to 2.8 mm,
somewhat swollen or globose elevated
spire, solid, with prosocline aperture.
Protoconch globose, maximum diam-
eter 0.3 mm, ending with varix and a
regular honeycomb sculpture. Ex -
posed and open umbilicus with a
chink, which is smooth or with a
spiral cord.
A
BC
D
E
F
G
100 µm
100 µm 100 µm
Five species are known in the NE
Atlantic of which four species were
described by H
OFFMAN ET AL
. (2008)
from the Rockall Bank: Lopheliella rock-
allensis, L. moolenbeeki, L. hermesae and L.
moundforceae; H
OFFMAN ET AL
. (2018)
described L. coralfishae from the Hatton
Bank.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
61
Figure 51. Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008. A, B: Tyro Seamount
– SMT2/DW278, H 2.1 mm, W 1.9 mm; C: same locality, W 1.7 mm; D: protoconch W 0.31
mm, same as C.
Figura 51. Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008. A, B: Banco Tyro –
SMT2/DW278, 2,1 mm alto, 1,9 mm ancho; C: misma localidad, 1,7 mm ancho; D: protoconcha
0,31 mm ancho, misma que C.
Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008 (Fig. 51)
Lopheliella rockallensis Hoffman, van Heugten & Lavaleye, 2008: 41, figs. 1-5, 20.
Material examined: Tyro Seamount • 4 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993;
SMT2/DW278; dredge.
Distribution: The species is known
from Rockall Bank (H
OFFMAN ET AL
.,
2008) and Tyro Seamount (this study),
557–925 m.
Remarks: This species has only been
encountered in two locations; in the Rockall
Bank it was found in association with
sponges (Hexactinellida) and coral rubble.
Lopheliella moolenbeeki Hoffman, van Heugten & Lavaleye, 2008 (Fig. 52)
Lopheliella moolenbeeki Hoffman, van Heugten & Lavaleye, 2008: 41-42, figs. 6-9, 21.
Material examined: Tyro Seamount • 5 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993;
SMT2/DW278; dredge.
AB
C
D100 µm
Distribution: The species is known
from Rockall- and Hatton Bank
(H
OFFMAN ET AL
., 2008), and Tyro
Seamount (this study), 557–958 m.
Remarks: It has been found in the
Rockall and Hatton Banks in association
with siliceous sponges (Hexactinellida)
and coral rubble.
Iberus, 38 (Suplemento 9), 2020
62
Figure 52. Lopheliella moolenbeeki Hoffman, van Heugten & Lavaleye, 2008. A, B: Tyro Seamount – SMT2
/DW278, H 1.6 mm, W 1.7 mm; C: same locality, W 1.3 mm; D: protoconch W 0.30 mm, same as C.
Figura 52. Lopheliella moolenbeeki Hoffman, van Heugten & Lavaleye, 2008. A, B: Banco Tyro –
SMT2/DW278, 1,6 mm alto, 1,7 mm ancho; C: misma localidad, 1,3 mm ancho; D: protoconcha
0,30 mm ancho, misma que C.
Genus Mikro Warén, 1996
Type taxon: Mikro globulus Warén, 1996 by original designation, off Iceland, 1099 m.
W
ARÉN
(1996) provided a diagnosis
of the shell: very small, with smooth
protoconch, apically keeled first teleo-
conch whorl, and intra-umbilical keel.
Five species are known in the Atlantic
and Mediterranean Sea: the type species,
M. cerion (Dall, 1927) from off SE U.S.A.,
M. giustii (Bogi & Nofroni, 1989) from off
southern Europe, M. hattonensis Hoffman,
van Heugten & Lavaleye, 2010 described
from the Hatton Bank, and M. oviceps
Ortega & Gofas, 2019 from the Canaries.
Mikro globulus Warén, 1996 (Fig. 53)
Mikro globulus Warén, 1996: 199, figs. 1C-F, 2, 7D, 8D, 10D.
Material examined: Atlantis Seamount • 1 shell; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404;
grab. Tyro Seamount • 1 shell; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993; SMT2/DW278; dredge.
Plato Seamount • 2 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge.
Little Meteor Seamount • 1 shell; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
A
BC
D100 µm
Distribution: This species has been
found off Iceland (W
ARÉ N
, 1996), the
Rockall Bank (F
REI WALD
& B
ECK
,
2007), and SASC (this study), 677–1500
m.
Remarks: Shell characterised by the
depressed spire with inflated whorls
and its flexuous outer lip.The umbilical
keel is similar to that of Xyloskenea Mar-
shall, 1988 and Trenchia Knudsen, 1964.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
63
Figure 53. Mikro globulus Warén, 1996. A, B: Plato Seamount – SMT2/DW250, H 1.2 mm, W
1.4 mm; C: same locality, W 1.4 mm; D: protoconch W 0.26 mm, same as C.
Figura 53. Mikro globulus Warén, 1996. A, B: Banco Plato – SMT2/DW250, 1,2 mm alto, 1,4 mm
ancho; C: misma localidad, 1,4 mm ancho; D: protoconcha 0,26 mm ancho, misma que C.
Mikro minima (G. Seguenza, 1876) comb. nov. (Fig. 54)
Trochus (Margarita) minima Seguenza, 1876: 186.
Trochus minutulus Jeffreys, 1883: 95, pl. 20 fig. 2.
Lissotesta minima: W
ARÉN
, 1992: 171-172, figs. 25E-F, 29A-C.
Material examined: Tyro Seamount • 20 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993;
SMT2/DW278; dredge. Plato Seamount •55 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993;
SMT2/DW250; dredge. Great Meteor Seamount • 1 shell; 29.601°N, 28.380°W; 550–575 m; 13 Jan.
1994; SMT2/DW166; dredge. Little Meteor Seamount • 1 shell; 29.654°N, 29.015°W; 865 m; 27 Oct. 2018;
M151/23434-R4; ROV sample. • 1 shell; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
Distribution: From the Rockall Bank
(H
OFFMAN ET AL
., 2010), Bay of Biscay to
the Ibero-Moroccan Gulf (W
ARÉN
, 1992),
the Canaries (O
RTEGA
& G
OFAS
, 2019,
misidentified as Mikro globulus), and
SASC (this study), 500–2300 m.
Remarks: This species has been placed
by W
ARÉN
(1992) in the genus Lissotesta
Bush, 1897, which has a partially hidden
protoconch and a rounded shoulder on
the initial whorls. The genus Mikro Warén,
1996 has an exposed protoconch and the
initial teleoconch has a flattened shoul-
der with a keel; the umbilical area is conical
with a weak keel. Mikro minima shares the
shell morphology of Mikro and not that of
Lissote sta. Its similarity to Mikro was
already highlighted by W
ARÉN
(1996: 199).
A
B
C
D100 µm
Iberus, 38 (Suplemento 9), 2020
64
Figure 54. Mikro minima (G. Seguenza, 1876). A-C: Plato Seamount – SMT2/DW250, H 1.1
mm, W 1.1 mm; D: same locality, H 1.4 mm, W 1.3 mm; E: umbilical view, same as D; F: same
locality, basal view, W 1.3 mm; G: same locality, apical view, W 1.2 mm; H: protoconch W 0.20
mm, same as G; I: apical view, W 1.0 mm; J: protoconch W 0.20 mm, same as I.
Figura 54. Mikro minima (G. Seguenza, 1876). A-C: Banco Plato – SMT2/DW250, 1,1 mm alto,
1,1 mm ancho; D: misma localidad, 1,4 mm alto, 1,3 mm ancho; E: vista umbilical, misma que D; F:
misma localidad, vista basal, 1,3 mm ancho; G: misma localidad, vista apical, 1,2 mm ancho; H: pro-
toconcha 0,20 mm ancho, misma que G; I: misma localidad, vista apical, 1,0 mm ancho; J: protocon-
cha 0,20 mm ancho, misma que I.
Mikro minima is most similar to Mikro
cerion (Dall, 1927), M. giusti i Bogi &
Nofroni, 1989 and M. hattonensis Hoffman,
van Heugten & Lavaleye, 2010; these
species have a similar protoconch, outline,
and cord on the shoulder of the initial
teleoconch. M. cerion and M. giustii are
more compressed than M. minima. M. hat-
tonensis has a pitted microsculpture on the
apex and the umbilical area.
A
B
C
D
E
F
H
I
G
J
100 µm
100 µm
100 µm
Distribution: Hatton- and Rockall
Bank (H
OFFMAN ET AL
., 2010), Galicia
Bank (SaMID 73164), Canaries (O
RTEGA
& G
OFAS
, 2019) and SASC (this study),
852–1500 m.
Remarks: We are uncertain on the spe-
cific determination of the specimens from
the SASC because the shells are eroded
and the pitted microsculpture is barely
visible. Mikro globulus and M. giustii have
a clearly lower spire and lack the apical
and umbilical pitted sculpture. Mikro per-
forata differs in that the pitted microsculp-
ture covers the whole shell.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
65
Figure 55. Mikro cf. hattonensis Hoffman, van Heugten & Lavaleye, 2010. A-C: Little Meteor
Seamount – M151/23436, H 1.0 mm, W 1.0 mm; D: protoconch W 0.20 mm.
Figure 55. Mikro cf. hattonensis Hoffman, van Heugten & Lavaleye, 2010. A-C: Pequeño Banco
Meteor – M151/23436, 1,0 mm alto1,0 mm ancho; D: protoconcha 0,20 mm ancho.
Mikro cf. hattonensis Hoffman, van Heugten & Lavaleye, 2010 (Fig. 55)
Mikro hattonensis Hoffman, van Heugten & Lavaleye, 2010: 51-52, figs. 15-22.
Material examined: Tyro Seamount • 1 shell; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993;
SMT2/DW278; dredge. Plato Seamount • 19 shells; 33.197°N, 28.949°W; 690–710 m; 31 Jan. 1993;
SMT2/DW242; dredge. • 1 shell; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250;
dredge. Little Meteor Seamount • 2 shells; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab.
Holotype, an empty shell (Figs. 57A-E):
Small (H 1.1 mm, W 1.0 mm), minute
shell with a regularly raised, stepped
outline, minutely pitted micro-sculpture,
spiral cords, open umbilicus and flat
apex, apical angle 70°, translucent white.
Protoconch: ½ whorls, finely pitted
sculpture, convex lip, W 0.20 mm. Tran-
sition to teleoconch clear by change in
sculpture (Fig. 57D).
Teleoconch: three angular whorls, deep
suture. Shell covered with micro-sculp-
Mikro perforata n. sp. (Figs. 56, 57)
Type material: Holotype, Plato Seamount • 1 shell (Figs. 57A-D); 33.210°N, 29.287°W; 1450–1500 m; 01
Feb. 1993; SMT2/DW250; dredge, in sediment with dead coral fragments; MNHN-IM-2000-35682.
Type locality: Plato Seamount – 33.210°N – 29.287°W, 1450–1500 m.
Etymology: perforata refers to the pitted microsculpture.
AB
C
D100 µm
ture of rounded pits (diameter 1–3 µm)
and fine growth lines, straight and slightly
prosocline on upper whorl. Two rounded
and smooth cords forming keels on the
upper whorl; upper keel bordering the
shoulder, a second keel above the suture.
Shoulder area sloping and flattened. Area
between cords slightly convex.
Base of body whorl with third cord
and keel demarcating the umbilical area.
Supraperipheral cords fade away on
body whorl. Umbilicus open, funnel-
shaped, deep. Inside umbilicus, one
strong spiral cord, strong growth mark-
ings.
Aperture 50% of shell height, oval,
flattened along parietal side. Union of
outer lip perpendicular to penultimate
whorl. Peristome with blunt edge, outer
lip prosocline, flexuous at the base. Co -
lumella thin and curved. Callus thin and
smooth, inside of whorl smooth.
Variability: unknown.
Distribution: only known from the
type locality.
Remarks: Placement in the genus Mikro
is based on the morphology of the shell;
the small size, an exposed protoconch, the
flat shoulder with spiral cord and keel, an
open, funnel-shaped umbilicus with a
strong cord and keel. It is similar to M.
minima, M. hattonensis, M. cerion and M.
giustii that all have a smooth whorl surface
whereas M. perforata n. sp. has a pitted
micro-sculpture covering the full shell.
Lissotesta scalaroides Rubio & Rolán,
2013 is exceedingly similar and probably
related, but differs in that the protoconch
is much less sunken, in lacking a periph-
eral and periumbilical keel and in having
a much less dense microsculpture on the
shell surface, particularly on the base. To
be consistent with the generic placement
of our new species, the new combination
Mikro scalaroides (Rubio & Rolán, 2013) is
here introduced.
Iberus, 38 (Suplemento 9), 2020
66
Figure 56. Mikro perforata n. sp., Plato Seamount – SMT2/DW250, holotype, apertural view, H 1.1 mm.
Figura 56. Mikro perforata n. sp., Banco Plato - SMT2/DW250, holotipo, vista apertural, 1,1 mm alto.
Genus Parviturbo Pilsbry & McGinty, 1945
Type taxon: Parviturbo rehderi Pilsbry & McGinty, 1945 by original designation. Its type locality
was Palm Beach, Florida, U.S.A., intertidal.
P
ILSBRY
& M
C
G
INTY
(1945) provided
a diagnosis of the shell of the genus:
small, solid, perforate, or narrowly
umbilicate, turbinate or globose-conic,
few strongly convex whorls, subequal
spiral ridges, intervals crossed by axial
threads. Aperture rounded, concave col-
umella thickened. Protoconch with one
or two smooth whorls. Operculum thin,
corneous, and multispiral.
200 µm
Thirty six extant and five fossil
species are currently known globally
according to M
OLLUSCA
B
ASE
(2020),
nine of them known in the NE Atlantic
and Mediterranean Sea (R
UBIO ET AL
.,
2015): Parviturbo elegantulus (Philippi,
1844), P. alboranensis Penas & Rolán,
2006, P. fenestratus (Chaster, 1896), P.
insularis Rolán, 1988, P. rolani Engl, 2001,
and four species described by R
UBIO ET
AL
. (2015): P. ergasticus, P. azoricus, P.
multispiralis, and P. seamountensis.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
67
Figure 57. Mikro perforata n. sp. A-C: Plato Seamount – SMT2/DW250, holotype H 1.1 mm, W
1.0 mm; D: protoconch W 0.20 mm; E: micro-sculpture of the body whorl.
Figura 57. Mikro perforata n. sp. A-C: Banco Plato – SMT2/DW250, holotipo 1,1 mm alto, 1,0 mm
ancho; D: protoconcha 0,20 mm ancho; E: microescultura de la última vuelta.
Parviturbo seamountensis Rubio, Rolán & Gofas, 2015 (Fig. 58)
Parviturbo seamountensis Rubio, Rolán & Gofas in R
UBIO ET AL
., 2015: 188, figs. 11A-B, 12 A-F.
Material examined: Atlantis Seamount• 1 shell; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018; M151/23404;
grab. • 2 shells; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Great Meteor Seamount
• 2 shells; 29.750°N, 28.533°W; 316 m; 14 Mar. 2010; POS397/89-5; grab. • 2 shells; 29.750°N, 28.533°W;
315 m; 14 Mar. 2010; POS397/89-6; grab. • 1 shell; 29.884°N, 28.601°W; 295 m; 14 Mar. 2010; POS397/90-
1; grab. • 2 shells; 29.884°N, 28.601°W; 295 m; 14 Mar. 2010; POS397/90-2; grab. • 1 shell; 29.884°N,
28.601°W; 294 m; 14 Mar. 2010; POS397/90-3; grab. • 4 shells; 30.083°N, 28.633°W; 310 m; 15 Mar. 2010;
POS397/91-10; grab. • 3 shells; 30.083°N, 28.634°W; 311 m; 15 Mar. 2010; POS397/91-11; grab. • 2 shells;
30.084°N, 28.566°W; 301 m; 15 Mar. 2010; POS397/92-2; grab. • 2 shells; 30.084°N, 28.566°W; 301 m;
15 Mar. 2010; POS397/92-3; grab. • 1 shell; 30.017°N, 28.533°W; 286 m; 16 Mar. 2010; POS397/95-5; grab.
• 1 shell; 30.017°N, 28.533°W; 288 m; 16 Mar. 2010; POS397/95-6; grab. • 11 shells; 30.084°N, 28.500°W;
309 m; 17 Mar. 2010; POS397/98-1; grab. • 2 shells; 30.084°N, 28.500°W; 330 m; 17 Mar. 2010;
POS397/98-2; grab. • 1 shell; 30.084°N, 28.501°W; 308 m; 17 Mar. 2010; POS397/98-3; grab. • 1 shell;
30.017°N, 28.467°W; 325 m; 17 Mar. 2010; POS397/99-6; grab. • 2 shells; 30.017°N, 28.467°W; 302 m;
17 Mar. 2010; POS397/99-7; grab. • 1 shell; 29.949°N, 28.500°W; 288 m; 18 Mar. 2010; POS397/100-4;
grab. • 3 shells; 29.950°N, 28.500°W; 289 m; 18 Mar. 2010; POS397/100-5; grab. • 1 shell; 29.950°N,
28.500°W; 291 m; 18 Mar. 2010; POS397/100-6; grab. • 2 shells; 29.951°N, 28.433°W; 309 m; 18 Mar. 2010;
POS397/101-5; grab. • 3 shells; 29.951°N, 28.433°W; 308 m; 18 Mar. 2010; POS397/101-7; grab. • 2 shells;
A
B
C
D
E
100 µm
100 µm
29.951°N, 28.567°W; 287 m; 19 Mar. 2010; POS397/102-1; grab. • 1 shell; 29.883°N, 28.533°W; 289 m;
19 Mar. 2010; POS397/103-5; grab. • 2 shells; 29.883°N, 28.466°W; 298 m; 19 Mar. 2010; POS397/104-
1; grab. • 8 shells; 29.883°N, 28.466°W; 301 m; 19 Mar. 2010; POS397/104-2; grab. • 1 shell; 29.883°N,
28.466°W; 301 m; 19 Mar. 2010; POS397/104-3; grab. • 5 shells; 29.816°N, 28.433°W; 299 m; 19 Mar. 2010;
POS397/106-1; grab. • 14 shells; 29.816°N, 28.433°W; 300 m; 19 Mar. 2010; POS397/106-2; grab. • 32
shells; 29.816°N, 28.433°W; 300 m; 19 Mar. 2010; POS397/106-3; grab. • 20 shells; 29.817°N, 28.567°W;
307 m; 20 Mar. 2010; POS397/109-5; grab. • 14 shells; 29.817°N, 28.567°W; 308 m; 20 Mar. 2010;
Iberus, 38 (Suplemento 9), 2020
68
Figure 58. Parviturbo seamountensis Rubio, Rolán & Gofas, 2015. A, B: Great Meteor Seamount,
POS397/111, H 1.0 mm, W 1.0 mm; C: microsculpture of the body whorl, same as A; D: proto-
conch W 0.20 mm, same as A; E, F: Great Meteor Seamount, M151/23419, H 1.4 mm, W 1.3
mm; G: microsculpture of body whorl, same as E; H: same locality, apical view, W 1.1 mm; I: pro-
toconch W 0.22 mm, same as H; J: same locality, basal view W 1.4 mm.
Figura 58. Parviturbo seamountensisRubio, Rolán & Gofas, 2015. A, B: Gran Banco Meteor, POS397/111,
1,0 mm alto, 1,0 mm ancho; C: microescultura de la última vuelta, misma que A; D: protoconcha 0,20
mm ancho, misma que A; E, F: Gran Banco Meteor, M151/23419, 1,4 mm alto, 1,3 mm ancho; G:
microescultura de la última vuelta, misma que E; H: misma localidad, vista apical, 1,1 mm ancho; I: pro-
toconcha, 0,22 mm ancho, misma que H; J: misma localidad, vista basal 1,4 mm ancho.
A
B
CD
E
F
H
I
G
J
100 µm 100 µm
100 µm 100 µm
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
69
Figure 59. Seamountiella azorica (Dautzenberg & H. Fischer, 1896). A, B: Plato Seamount –
SMT2/DW250, H 2.2 mm, W 4.0 mm; C: protoconch W 0.27 mm, same as B; D, E: same local-
ity, H 2.5 mm, 4.1 mm. F, G: Little Meteor Seamount – M151/23436, H 2.1 mm, W 3.4 mm;
H: same locality, apical view, W 2.1 mm; I: protoconch W 0.24 mm, same as H.
Figura 59. Seamountiella azorica (Dautzenberg y H. Fischer, 1896). A, B: Banco Plato - SMT2/DW250,
2,2 mm alto, 4.0 mm ancho; C: protoconcha 0,27 mm ancho, misma que B; D, E: misma localidad, 2,5
mm alto, 4.1 mm ancho. F, G: Pequeño Banco Meteor - M151/23436, 2,1 mm alto, 3.4 mm ancho; H:
misma localidad, vista apical, 2,1 mm ancho; I: protoconcha 0,24 mm ancho, misma que H.
Distribution: SASC, 274–852 m
(R
UBIO ET AL
., 2015; this study).
Remarks: This species was described
from the Great Meteor Seamount at 470
m (R
UBIO ET AL
., 2015). It can be easily
identified by its strong and coarsely
reticulated sculpture. P. rectangularis
Rubio, Rolán & Fernández-Garcés, 2015
of Guadeloupe is similar but this species
has a finer sculpture on the early teleo-
conch and a less pronounced outer lip.
All remaining species in the genus have
a dominant spiral sculpture with finer
axial riblets.
POS397/109-7; grab. • 20 shells; 29.750°N, 28.466°W; 291 m; 21 Mar. 2010; POS397/111-1; grab. • 25
shells; 29.750°N, 28.466°W; 292 m; 21 Mar. 2010; POS397/111-2; grab. • 10 shells; 29.750°N, 28.466°W;
293 m; 21 Mar. 2010; POS397/111-3; grab. • 1 shell; 29.816°N, 28.500°W; 298 m; 21 Mar. 2010;
POS397/112-6; grab. • 3 shells; 29.749°N, 28.400°W; 293 m; 21 Mar. 2010; POS397/113-1; grab. • 12
shells; 29.683°N, 28.434°W; 288 m; 21 Mar. 2010; POS397/114-5; grab. • 31 shells; 29.683°N, 28.434°W;
289 m; 21 Mar. 2010; POS397/114-6; grab. • 40 shells; 29.683°N, 28.434°W; 289 m; 21 Mar. 2010;
POS397/114-7; grab. • 41 shells; 29.750°N, 28.533°W; 319 m; 24 Oct. 2018; M151/23419-2; grab. Little
Meteor Seamount • 1 shell; 29.654°N, 29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab. • 30 shells;
29.655°N, 29.004°W; 464 m; 27 Oct. 2018; M151/23438; grab. • 28 shells; 29.645°N, 28.975°W; 284 m;
27 Oct. 2018; M151/23440; grab. • 5 shells; 29.633°N, 28.976°W; 282 m; 27 Oct. 2018; M151/23441;
grab. • 18 shells; 29.633°N, 28.983°W; 274 m; 27 Oct. 2018; M151/23442; grab.
A
BC
D
E
F
H
I
G
100 µm
100 µm
Genus Seamountiella Rubio, Gofas & Rolán, 2019
Type taxon: Tinostoma azorica Dautzenberg & Fischer, 1896 by original designation, Azores.
bilicus covered by columellar callus even
in juvenile stage. Aperture rounded,
slightly prosocline; columella arched;
outer lip thin, smooth edge.
Four extant species are currently
known globally (R
UBIO ET AL
., 2019),
two of them live in the NE Atlantic: the
type taxon Seamountiella azorica
(Dautzenberg & H. Fischer, 1896) and S.
dimidia Rubio, Gofas & Rolán, 2019.
Both of them were found on the SASC.
Iberus, 38 (Suplemento 9), 2020
70
Figure 60. Seamountiella dimidia Rubio, Gofas & Rolán, 2019, Atlantis Seamount –
M151/23404. A, B: H 1.3 mm, W 2.0 mm; C, D: same locality, H 1.3 mm, W 2.0 mm; E: pro-
toconch W 0.22 mm, same as D.
Figura 60. Seamountiella dimidia Rubio, Gofas & Rolán, 2019. A, B: Banco Atlantis - M151/23404,
1,3 mm alto, 2,0 mm ancho; C, D: misma localidad, H 1,3 mm alto, 2,0 mm ancho; E: protoconcha
0,22 mm ancho, misma que D.
R
UBIO ET AL
. (2019) provided a diag-
nosis for shells of the genus: solid,
smooth and very shiny. Spire depressed,
with flattened apex; periphery and base
convex. Protoconch of 0.75 whorl,
smooth. Teleoconch with an initial phase
of 0.5 to 2 whorls, in which the whorl di-
ameter increases slowly and there are
marked growth lines, and a final phase
of 1.1 to 2 whorls, in which the diameter
of the whorl increases more rapidly. Um-
Seamountiella azorica (Dautzenberg & H. Fischer, 1896) (Fig. 59)
Tinostoma azorica Dautzenberg & Fischer, 1896: 485, pl. 21, figs. 16-18 [Type locality: Azores
Islands, Pr. Alice, Stn 46, 1385 m - Stn 117, 2102 m].
Seamountiella azorica: R
UBIO
, G
OFAS
& R
OLÁN
, 2019: 251-258, figs. 1A-C, 3A-F, 4A-C.
Material examined: Azores, Mar da Prata • 21 shells; 37.673°N, 25.925°W; 595 m; 08 Oct. 2018;
M151/23111; grab. • 17 shells; 37.661°N, 25.918°W; 599 m; 08 Oct. 2018; M151/23112; grab. • 2
shells; 37.659°N, 25.789°W; 599 m; 19 Oct. 2018; M151/23181; box core. Plato Seamount • 9
shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Great Meteor
Seamount • 9 shells; 29.565°N, 28.339°W; 944 m; 25 Oct. 2018; M151/23425-R6; ROV sample • 14
A
B
C
D
E100 µm
Distribution: Hatton Bank (H
OFFMAN
ET AL
., 2011), Azores (D
AUTZENBERG
& F
IS
-
CHER
, 1896; L
OCARD
, 1898; this study),
SASC (R
UBIO ET AL
., 2019; this study), Ga -
licia Bank (R
UBIO ET AL
., 2019), Lu si ta nian
seamounts and banks (B
ECK ET AL
., 2006;
H
OFFMAN
& F
REIWALD
, 2017), off western
Morocco (L
OCARD
, 1898), 470–4060 m.
Remarks: The genus has been tenta-
tively placed in Skeneidae based on the
radula and the operculum of Seamoun-
tiella azorica (R
UBIO ET AL
., 2019).
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
71
Figure 61. Skenea ponsonbyi (Dautzenberg & H. Fischer, 1897). A, B: Tyro Seamount –
SMT2/DW278, H 1.35 mm, W 1.52 mm; C: microsculpture, same as A; D: same locality, W
1.29 mm; E: protoconch W 0.29 mm.
Figura 61. Skenea ponsonbyi (Dautzenberg y H. Fischer, 1897). A, B: Banco Tyro - SMT2/DW278,
1,35 mm alto, 1,52 mm ancho; C: microescultura, misma que A; D: misma localidad, 1,29 mm
ancho; E:protoconcha 0,29 mm ancho.
shells; 29.568°N, 28.339°W; 855 m; 25 Oct. 2018; M151/23425-R9; ROV sample. • 2 shells;
30.082°N, 28.730°W; 1032 m; 26 Oct. 2018; M151/23429-R1; ROV sample. • 4 shells; 30.086°N,
28.726°W; 906 m; 26 Oct. 2018; M151/23429-R8; ROV sample. Little Meteor Seamount • 7 shells;
29.654°N, 29.015°W; 865 m; 27 Oct. 2018; M151/23434-R4; ROV sample. • 72 shells; 29.654°N,
29.015°W; 852 m; 27 Oct. 2018; M151/23436; grab. • 1 live-collected specimen, six shells;
29.654°N, 29.014°W; 811 m; 27 Oct. 2018; M151/23437; grab.
Seamountiella dimidia Rubio, Gofas & Rolán, 2019 (Fig. 60)
Seamountiella dimidia R
UBIO
, G
OFAS
& R
OLÁN
, 2019: 258-259, figs. 6A-C, 7A-F.
Material examined: Atlantis Seamount • 280 shells; 33.971°N, 30.206°W; 677 m; 21 Oct. 2018;
M151/23404; grab. • 280 shells; 33.996°N, 30.177°W; 617 m; 21 Oct. 2018; M151/23408; grab. Plato
Seamount • 5 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb. 1993; SMT2/DW250; dredge. Little
Meteor Seamount • 1 shell; 29.655°N, 29.004°W; 464 m; 27 Oct. 2018; M151/23438; grab.
AB
C
D
E100 µm
100 µm
Distribution: SASC, 280–1500 m
(R
UBIO ET AL
., 2019; this study).
Remarks: Seamountiella dimidia is
smaller than S. azorica, it has two differ-
entiated growth phases, it shows a pro-
truding outer lip in adult specimens and
it lacks a perforation in the parietal
callus.
Iberus, 38 (Suplemento 9), 2020
72
Figure 62. Skenea basicarinata n. sp. A: Tyro Seamount – SMT2/DW278, holotype, apertural
view, H 2.7 mm; B: paratype 2, apical view of smooth protoconch, W 0.37 mm, followed by
initial teleoconch with weak supraperipheral cord.
Figura 62. Skenea basicarinata n. sp. A: Monte submarino Tyro - SMT2/DW278, holotipo, vista aper-
tural, 2,7 mm alto; B: paratipo 2, vista apical de la protoconcha lisa, 0,37 mm ancho, seguida del
inicio de la teleoconcha con cordón supraperiférico débil.
Genus Skenea J. Fleming, 1825
Type taxon: Helix serpuloides Montagu, 1808 by subsequent designation. Its type locality is
Devon, England.
The genus is used as a catchall for
fragile, small depressed gastropods with
a simple, smooth protoconch of less
than one whorl. The spire may be flat or
moderately raised, smooth or sculp-
tured by spiral cords and/or axial ribs.
Umbilicus may be open or closed. Aper-
ture rounded, prosocline. Morphologi-
cal variability of the shell within the
genus is large. H
ASZPRUNAR ET AL
.
(2016) provided a complete anatomical
description of the type species through
serial semi-thin sectioning and 3D
reconstructions, and gave a diagnosis
based on soft parts.
Near thirty extant species are cur-
rently known globally, most of them
living in the NE Atlantic and some of
them probably unrelated to the type
species. Skenea ponsonbyi (Dautzenberg
& H. Fischer, 1897) was encountered in
the SASC and one additional new
species is proposed below: Skenea basi-
carinata n. sp.
Skenea ponsonbyi (Dautzenberg & H. Fischer, 1897) (Figs. 61A-E)
Cyclostrema ponsonbyi Dautzenberg & H. Fischer, 1897: 176, pl. 4 figs. 12-14.
Material examined: Atlantis Seamount • 1 shell; 34.412°N, 30.513°W; 795–830 m; 03 Feb. 1993;
SMT2/DW264; dredge. Tyro Seamount • 2 shells; 33.963°N, 28.373°W; 890–925 m; 06 Feb. 1993;
SMT2/DW278; dredge.
200 µm
A
B
1 mm
Distribution: Azores (D
AUTZENBERG
& H. F
ISCHER
, 1897) and SASC (this
study), 795–1600 m.
Remarks: Skenea ponsonbyi is provi-
sionally placed in the genus Skenea
based on its protoconch and outline; it is
a skeneimorph but its systematic place-
ment is uncertain, and a new genus is
not pertinent until the soft parts are
known.
The three specimens from the SASC
were juveniles. The specimen described
and illustrated by D
AUTZENBERG
& H.
F
ISCHER
(1897) has a height of 2.7 mm.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
73
Figure 63. Skenea basicarinata n. sp. A, B: Tyro Seamount – SMT2/DW278, holotype, H 2.7 mm,
W 3.3 mm; C: paratype 1, same locality, H 2.8 mm, W 3.4 mm; D: paratype 2, same locality, W
3.4 mm; protoconch W 0.37 mm, same as D; F: magnified surface of the framed area on D.
Figura 63. Skenea basicarinata n. sp. A, B: Banco Tyro - SMT2/DW278, holotipo, 2,7 mm alto, 3.3 mm
ancho; C: paratipo 1, misma localidad, 2,8 mm alto, 3.4 mm ancho; D: paratipo 2, misma localidad, 3.4
mm ancho; E: protoconcha 0,37 mm ancho, misma que D; F: superficie enmarcada en D, aumentada.
Skenea basicarinata n. sp. (Figs. 62, 63)
Type material: Holotype, Tyro Seamount • 1 shell (Figs. 63A-B); 33.963°N, 28.373°W; 890–925 m;
06 Feb. 1993; SMT2/DW278; dredge, in sediment with live and dead corals, live sponges, brachio-
pods, echinoderms and crustaceans; MNHN-IM-2000-35683. Paratypes: • 1 shell (Figs. 63C-F); same
data as for holotype; MNHN-IM-2000-35684. • 2 shells; same data as for holotype; MNHN-IM-
2000-35685.
Other material examined: Atlantis Seamount • 4 shells; 34.412°N, 30.513°W; 795–830 m; 03 Feb.
1993; SMT2/DW264; dredge. Plato Seamount • 2 shells; 33.210°N, 29.287°W; 1450–1500 m; 01 Feb.
1993; SMT2/DW250; dredge. Great Meteor Seamount • 1 shell; 29.750°N, 28.533°W; 319 m; 24 Oct.
2018; M151/23419-2; grab.
Type locality: Tyro Seamount – 33.963°N – 28.373°W, 890–925 m.
Etymology: basicarinata refers to the strong umbilical cords.
Holotype, an empty shell (Figs. 63A-B):
Small (H 2.7 mm, W 3.3 mm), moderately
solid shell with a flattened apex, convex
whorls, strong basal spiral cords, white.
Protoconch: ½ whorls, large nucleus,
smooth, with convex lip, W 0.37 mm.
Slightly raised above teleoconch. Transi-
tion to teleoconch inconspicuous by fine
A
B
C
DEF100 µm
100 µm
lip and teleoconch with spiral cord (Fig.
63E of paratype 2).
Teleoconch: 2 ½ rounded whorls.
Suture shallow, impressed.
First whorl with one weak, smoothly
rounded cord on the shoulder, fading
away towards second whorl. Surface
smooth with few fine growth markings.
Microsculpture with numerous rounded
shallow pits, pit diameter about 1–3 µm.
Body whorl descending, supraperiph-
eral cord faded,
Base of body whorl with six spiral
cords, two strong smooth cords widely
spaced outside umbilical area, four fine
cords closely spaced near periphery.
Umbilicus open, narrow, deep, tortuous,
partly covered by columellar callus.
Inside smooth with few coarse growth
lines.
Aperture 60% of shell height, nearly
circular with slight indent at parietal side,
angular near the union with penultimate
whorl, which is perpendicular. Peristome
thick, smooth and rounded, outer lip
prosocline at 20° with spire axis, opening
plane nearly flat. Columella curved. Callus
thick and smooth with thickened rim
inside columellar and parietal lip, inside
of whorl smooth with slight undulating
growth markings.
Distribution: SASC, 319–1500 m.
Remarks: The placement in the genus
Skenea is based on the protoconch and
its similarity with the type species,
Skenea serpuloides, and Skenea basistriata
(Jeffreys, 1887). The latter has more, but
weaker spiral cords in the umbilical area
and frequently weak spiral cords on the
upper whorl surface.
Iberus, 38 (Suplemento 9), 2020
74
Schematic distributions of
skeneimorph species known from the
SASC, the Azores and the Lusitanian
seamounts are given in Tables I and II.
The species in Seguenzioidea are listed
in Table I and those in Skeneidae are
given in Table II. The species from the
Azores have been mainly reported by
D
AUTZENBERG
& F
ISCHER
(1897), R
UBIO
ET AL
. (2015) or were found during
cruise M151. Those from the Lusitanian
seamounts have been mentioned by
B
ECK ET AL
. (2006) and H
OFFMAN
&
F
REIWALD
(2017). The skeneimorphs
from the wider NE Atlantic region have
been mostly reported on by W
ARÉN
(1992), and H
OFFMAN ET AL
.(2008, 2010,
2018) and some unreported specimens
are retained in the reference collection in
SaM. The species from the NW Atlantic
were listed in R
OSENBERG
(2009), R
UBIO
ET AL
. (2011) or from material in the col-
lection in SaM; the latter was collected
in various deep-water coral locations
along the eastern coast of the U.S.A. and
in the Gulf of Mexico.
The biodiversity of skeneimorph
species belonging to Seguenzioidea and
Trochoidea on the SASC is relatively
high when compared to most molluscan
superfamilies; 46 species were identi-
fied, 32 of which were assigned to
Seguenzioidea and 14 to Trochoidea
(Skeneidae). Seventeen taxa are newly
described in this paper.
Three species are transferred to dif-
ferent genera: Trenchia xenos is a new
combination for Xyloskenea xenos
Hoffman, van Heugten & Lavaleye,
2010, Mikro minima is a new combina-
tion for Trochus (Margarites) minima
Seguenza, 1876 and Mikro scalaroides for
Lissotesta scalaroides Rubio & Rolán,
2013.
Twelve species are currently only
known from the SASC (26%) and they
are likely endemic to this area. Nine
additional species also occur on the
seamounts near the Azores; 21 species
or 46% are therefore only known from
the SASC and/or the Azores seamounts
and these can be considered as endemic
to this larger area (Fig. 1B). G
OFAS
(2003)
discussed a complete endemism in the
genus Trituba within Cerithiopsidae
from the SASC. Likewise, G
OFAS
(2007)
pointed out that near 80% of Rissoidae
are presumed to be endemic of the
SASC, and H
OFFMAN ET AL
. (2020a) that
about 50% of the Seguenziidae are pro -
DISCUSSION
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
75
T
able I. Distribution of bathyal “skeneimorph” Seguenzioidea species known from the SASC, the Azores
and the Lusitanian seamounts. The NE and NW Atlantic are indicated for those species also known out-
side the first three key regions. Coding used for distribution classes, M: SASC only; A: SASC and
Azores seamounts; S: SASC, Azores and Lusitanian seamounts; X: NE Atlantic; W: amphiatlantic.
Tabla I. Distribución de especies de Seguenzioidea “skeneimorfos” batiales conocidas de la SASC, Azores
y montes submarinos lusitánicos. El Atlántico NO y NE se indican para aquellas especies que también se
conocen fuera de las tres primeras regiones clave. Codificación utilizada para las categorías de distribu-
ción, M: SASC solamente; A: montes submarinos de la SASC y Azores; S: SASC, montes submarinos de
Azores y lusitánicos; X: NE Atlántico; W: anfiatlántico.
S
EGUENZIOIDEA
NW Atlantic MET HY IRV PLA TYR ATL Azores Lusitan. SMTs NE Atlantic
T
OTAL SPECIES
5 32 16 23 23
Rugulina fragilis WWWWWW
Trochaclis islandica WW W
Trochaclis versiliensis XXXX X
Trochaclis fortis n. sp. M
Trochaclis carinata n. sp. M
Trochaclis platoensis n. sp. M
Eudaronia aperta XXX
Eudaronia mikra n. sp. MM
Eudaronia spirata n. sp. M
Adeuomphalus ammoniformis XXX
Adeuomphalus axistriatus n. sp. M
Adeuomphalus curvistriatus n. sp. M
Adeuomphalus densicostatus XXXX
Adeuomphalus sinuosus XX
Palazzia planorbis WWW
Akritogyra curvilineata XX
Akritogyra similis XXXXX
Anekes anderswareni n. sp. SS S S S S S
Anekes mikrosculpta n. sp. AAAAA
Anekes paucistriata XX X X X X X X
Anekes sculpturata XX
Anekes umbilisculpta n. sp. AA
Anekes varisculpta n. sp. AAAAA
Granigyra granulifera XXX
Granigyra pruinosa XX
Granigyra tenera XX
Retigyra granulosa XX
Retigyra iheringi AA
Lissotesta gittenbergeri XX X
Lissotesta turrita XX
Moelleriopsis messanensis XX
Moelleriopsis richardi SSS S S
Moelleriopsis normani SSS
Moelleriopsis atlantis n. sp. AAAAA
Moelleriopsis gritta n. sp. AAAA
Moelleriopsis meteorminora n. sp. M
Xyloskenea naticiformis WW WWW W W
Xyloskenea translucens WW W W
Trenchia biangulata XXX
Trenchia teriuga n. sp. AAAAA
Trenchia xenos comb. nov. XXXXX X
Iberus, 38 (Suplemento 9), 2020
76
Table II. Distribution of bathyal “skeneimorph” Trochoidea species known from the SASC, the
Azores seamounts and the Lusitanian seamounts. Same codes as for Table I.
Tabla II. Distribución de especies de Trochoidea “skeneimorfos” batiales conocidas de la SASC, montes
submarinos de Azores y montes submarinos lusitánicos. Mismos códigos que en Tabla I.
S
KENEIDAE
NW Atlantic MET HY IRV PLA TYR ATL Azores Lusitan. SMTs NE Atlantic
T
OTAL SPECIES
1 14 77 12
Cirsonella romettensis XX
Cirsonella ateles AAA A A A A
Cirsonella gaudryi XX X X X X X
Dikoleps cutleriana XX
Dikoleps nitens XX
Ganesa nitidiuscula WW WWWW W W
Lissomphalia bithynoides XX
Lopheliella rockallensis XX
Lopheliella moolenbeeki XX
Mikro giustii XX
Mikro globulus XXXX X
Mikro hattonensis XX X
Mikro minima n. comb. XXXXXX
Mikro perforata n. sp. M
Mikro scalaroides n. comb. MX
Parviturbo azoricus A
Parviturbo seamountensis MMM M M
Seamountiella azorica XXX X X X X X
Seamountiella dimidia MMM M M
Skenea ponsonbyi AA A
Skenea basicarinata n. sp. MMMM
bably also endemic on these seamounts.
Likewise, H
OFFMAN ET AL
. (2020b) noted
an endemicity of 91% in the genus
Papuliscala within Epitoniidae, and
G
OFAS
& H
OFFMAN
(2020) reported an
endemicity of 42% in the genus Callios-
toma. The isolated location of the SASC
has probably contributed to this high
degree of endemism.
Five amphiatlantic species were
found (11% of SASC species): Ganesa
nitidiuscula Jeffreys, 1883, Rugulina frag-
ilis (G.O. Sars, 1878), Trochaclis islandica
Warén, 1989, Xyloskenea naticiformis Jef-
freys, 1883 and Xyloskenea translucens
(Dall, 1927). The occurrence of some of
these amphiatlantic taxa was to be
expected assuming that a suitable
habitat for this fauna exists on the SASC.
Six new species were solely encoun-
tered in one dredge sample on the Plato
Seamount (SMT2/DW250, 1400–1500
m): Trochaclis carinata n. sp., Trochaclis
platoensis n. sp., Adeuomphalus axistriatus
n. sp., Adeuomphalus curvistriatus n. sp.,
Eudaronia spirata n. sp. and Mikro perfo-
rata n. sp. Obviously, it can be expected
that more skeneimorph species are to be
discovered on the SASC once more
extensive sampling is done.
Most of the encountered skeneimorph
taxa have a wide bathymetric range, some
of them occurring deeper than 2000 m (see
S
YSOEV
, 2014); about 50% of them are
known from the continental slopes, banks
and seamounts of the NE Atlantic Ocean.
Few species are also known in the western
Mediterranean Sea. It is likely that the
origin of most skeneimorph species is from
the north-eastern Atlantic.
The simple protoconchs of ske -
neimorph species suggest a non-plank-
totrophic larval development. It is yet un-
known how some vetigastropods manage
to cross abyssal gaps of some 1000 km in
the central Atlantic without suitable ba-
thyal habitats as stepping stones, whereas
other species are restricted to a smaller
distribution area like the SASC. One pos-
sibility as a consequence of their small size
is drifting as adults in the plankton, as was
documented for Anekes paucistriata by
W
ARÉN
(1992). The skeneimorph taxa of
the SASC seem to have a similar restricted
distribution and dispersal capability as
other vetigastropods such as the species
of Clelandella within Trochidae (G
OFAS
,
2005), Seguenziidae (H
OFFMAN ET AL
.,
2020a), and Calliostomatidae (G
OFAS
&
H
OFFMAN
, 2020).
Only Trochaclis versiliensis, Eudaronia
spirata, Trenchia xenos, Cirsonella gaudryi
and Seamountiella azorica were collected
alive and were found dry inside their
shells during sorting through the large
volume of sediment. The strikingly low
number of live-collected specimens
compared to shells may be explained by
the sedimentological setting of the
seamounts (
VON
R
AD
, 1974). There is no
terrigenous input, the pelagic sediment
consisting of foraminiferal and pteropod
shells is so light that it is immediately
winnowed to deeper parts. The only sig-
nificant sources of sediment on the
summit platforms are the products of
local erosion and the benthic calcareous
remains produced in situ, including
shells. This may explain why the sedi-
ment contains relatively large quantities
of shells, some of which may be hun-
dreds or thousands of years old.
ACKNOWLEDGEMENTS
Crews and scientific staffs of cruises
SEAMOUNT 2 (R/V S
UROIT
), POS397
(R/V P
OSEIDON
) and M151 (R/V
M
ETEOR
) are thanked for their dedica-
tion in collecting the samples used in
this study. Kai Horst George and Achim
Wehrmann yielded access to the mater-
ial of cruise POS397. Helmut Zibrowius
identified corals sampled during
SEAMOUNT 2. Nicol Mahnken is
acknowledged for sample retention at
SaM and for preparing SEM samples.
Hendrik Gheerardyn made the draw-
ings of the new species. POS397 and
M151 were funded by the Deutsche
Forschungsgemeinschaft. We are grate-
ful to José Templado and Anders Warén
for critically reading the manuscript and
providing most helpful comments in
order to improve it.
H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
77
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H
OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
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Iberus, 38 (Suplemento 9), 2020
80
Alphabetial Index (Main entries for the taxa are in boldface)
abyssicola, Moelleriopsis . . . . . . . . . . . . . . . . . . . .40, 44
Adeuomphalus . . . . . . . . . . . . . . . . . . . . . . . . .18
affinis, Anekes . . . . . . . . . . . . . . . . . . . . . . . .27, 36
Akritogyra . . . . . . . . . . . . . . . . . . . . . . . . . . .25
alboranensis, Parviturbo . . . . . . . . . . . . . . . . . . . . . .67
ammoniformis, Adeuomphalus . . . . . . . . . . . . . . .18, 21, 24
anderswareni, Anekes . . . . . . . . . . . . . . . . . . .31, 34, 36
Anekes . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
anselmoi, Trenchia . . . . . . . . . . . . . . . . . . . . . . .50, 52
antarctica, Trochaclis . . . . . . . . . . . . . . . . . . . . . . . .6
aperta, Eudaronia . . . . . . . . . . . . . . . . . . . .15, 16, 18
aperta, Omalogyra . . . . . . . . . . . . . . . . . . . . . . . .15
arenosa, Granigyra . . . . . . . . . . . . . . . . . . . . . . . .38
ateles, Cirsonella . . . . . . . . . . . . . . . . . . . . . .55, 58
ateles, Tharsis . . . . . . . . . . . . . . . . . . . . . . . . . .55
atlantis, Moelleriopsis . . . . . . . . . . . . . . . . . . . . .42
atypica, Trochaclis . . . . . . . . . . . . . . . . . . . . . . . .10
australis, Cirsonella . . . . . . . . . . . . . . . . . . . . . . .55
axistriatus, Adeuomphalus . . . . . . . . . . . . . . . .21, 24, 25
azorica, Tinostoma . . . . . . . . . . . . . . . . . . . . . . . .70
azorica, Seamountiella . . . . . . . . . . . . . . . . . . . .70, 72
azoricus, Parviturbo . . . . . . . . . . . . . . . . . . . . . . .67
basicarinata, Skenea . . . . . . . . . . . . . . . . . . . . .72, 73
biangulata, Trenchia . . . . . . . . . . . . . . . . . .49, 50, 52, 55
bucina, Trochaclis . . . . . . . . . . . . . . . . . . . . . . . .10
carinata, Trochaclis . . . . . . . . . . . . . . . . . . . . .10, 14
cerion, Mikro . . . . . . . . . . . . . . . . . . . . . . .62, 64, 66
Cirsonella . . . . . . . . . . . . . . . . . . . . . . . . . . .55
conspicua, Akritogyra . . . . . . . . . . . . . . . . . . . . .25, 26
coralfishae, Lopheliella . . . . . . . . . . . . . . . . . . . . . .61
costulifera, Xyloskenea . . . . . . . . . . . . . . . . . . . . . .47
curvilineata, Akritogyra . . . . . . . . . . . . . . . . . . . .25, 27
curvistriatus, Adeuomphalus . . . . . . . . . . . . . . . . . . .24
densicostata, Homalogyra . . . . . . . . . . . . . . . . . . . . .21
densicostatus, Adeuomphalus . . . . . . . . . . . .17, 18, 21, 24, 25
diegoalejandroi, Adeuomphalus . . . . . . . . . . . . . . . . . . .21
dimidia, Seamountiella . . . . . . . . . . . . . . . . . . . . . .70
dimidia, Seamountiella . . . . . . . . . . . . . . . . . . . . .71
elegantulus, Parviturbo . . . . . . . . . . . . . . . . . . . . . .67
ergasticus, Parviturbo . . . . . . . . . . . . . . . . . . . . . . .67
Eudaronia . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Eudaroniidae . . . . . . . . . . . . . . . . . . . . . . . . . .14
fenestratus, Parviturbo . . . . . . . . . . . . . . . . . . . . . .67
fortis, Trochaclis . . . . . . . . . . . . . . . . . . . . . . . . .8
fragilis, Rugulina . . . . . . . . . . . . . . . . . . . . . . . .5
fragilis, Adeorbis . . . . . . . . . . . . . . . . . . . . . . . . .5
Ganesa . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
gaudryi, Cirsonella . . . . . . . . . . . . . . . . . . . . . . . .55
gaudryi, Cirsonella . . . . . . . . . . . . . . . . . . . .55, 56, 58
gaudryi, Tharsis . . . . . . . . . . . . . . . . . . . . . . . . .56
giustii, Mikro . . . . . . . . . . . . . . . . . . . . .62, 64, 65, 66
globulus, Mikro . . . . . . . . . . . . . . . . . . . . . . .62, 65
Granigyra . . . . . . . . . . . . . . . . . . . . . . . . . . .37
granulifera, Granigyra . . . . . . . . . . . . . . . . . . . . .38
granulosa, Rerigyra . . . . . . . . . . . . . . . . . . . . . . .39
gritta, Moelleriopsis . . . . . . . . . . . . . . . . . . . . . .44
hattonensis, Mikro . . . . . . . . . . . . . . . . . . .62, 64, 65, 66
helicella, Akritogyra . . . . . . . . . . . . . . . . . . . . . . .26
hendersoni, Lydiphnis . . . . . . . . . . . . . . . . . . . . . . .55
hendersoni, Cyclostremiscus . . . . . . . . . . . . . . . . . . . .55
hermesae, Lopheliella . . . . . . . . . . . . . . . . . . . . . . .61
iheringi, Retigyra . . . . . . . . . . . . . . . . . . . . . . . .39
iheringi, Cyclostrema . . . . . . . . . . . . . . . . . . . . . . .39
inflata, Granigyra . . . . . . . . . . . . . . . . . . . . . . .36, 38
insularis, Parviturbo . . . . . . . . . . . . . . . . . . . . . . .67
islandica, Trochaclis . . . . . . . . . . . . . . . . . . . . . .6, 7
jaffaensis, Cyclostrema . . . . . . . . . . . . . . . . . . . . . .14
limata, Granigyra . . . . . . . . . . . . . . . . . . . . . . . .37
Lopheliella . . . . . . . . . . . . . . . . . . . . . . . . . . .60
messanensis, Moelleriopsis . . . . . . . . . . . . . . . .40, 41, 42, 47
meteorminora, Moelleriopsis . . . . . . . . . . . . . . . . . . .46
mikra, Eudaronia . . . . . . . . . . . . . . . . . . . . . . . .16
Mikro . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
mikrosculpta, Anekes . . . . . . . . . . . . . . . . . . . .27, 36
millipunctata, Retigyra . . . . . . . . . . . . . . . . . . . . . .39
millipunctatum, Cyclostrema . . . . . . . . . . . . . . . . . . . .39
minima, Mikro . . . . . . . . . . . . . . . . . . . . . . .63, 66
minima, Trochus (Margarita) . . . . . . . . . . . . . . . . . . . .63
minima, Lissotesta . . . . . . . . . . . . . . . . . . . . . . . .63
minutulus, Trochus . . . . . . . . . . . . . . . . . . . . . . . .63
Moelleriopsis . . . . . . . . . . . . . . . . . . . . . . . . .40
monterosatoi, Daronia . . . . . . . . . . . . . . . . . . . . . . .5
monterosatoi, Rugulina . . . . . . . . . . . . . . . . . . . . . . .5
moolenbeeki, Lopheliella . . . . . . . . . . . . . . . . . . . .61
moundforceae, Lopheliella . . . . . . . . . . . . . . . . . . . . .51
multispiralis, Parviturbo . . . . . . . . . . . . . . . . . . . . .67
naticiformis, Cithna . . . . . . . . . . . . . . . . . . . . . . .48
naticiformis, Xyloskenea . . . . . . . . . . . . . . . . . . .48, 55
nitidiuscula, Ganesa . . . . . . . . . . . . . . . . . . . . . .58
nofronii, Choristella . . . . . . . . . . . . . . . . . . . . . . .52
normani, Moelleriopsis . . . . . . . . . . . . . . . . . . . . . .40
normani, Moelleriopsis . . . . . . . . . . . . . . . . . .41, 42, 47
normani, Cyclostrema . . . . . . . . . . . . . . . . . . . . . . .41
oviceps, Mikro . . . . . . . . . . . . . . . . . . . . . . . . . .62
panamensis, Ganesa . . . . . . . . . . . . . . . . . . . . . . .58
Parviturbo . . . . . . . . . . . . . . . . . . . . . . . . . . .66
paucistriata, Anekes . . . . . . . . . . . . . . . . . .27, 33, 34, 36
Pendromidae . . . . . . . . . . . . . . . . . . . . . . . . . .5
perforata, Mikro . . . . . . . . . . . . . . . . . . . . . . .65, 66
platoensis, Trochaclis . . . . . . . . . . . . . . . . . . . . . .11
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OFFMAN ET AL
.: “Skeneimorph” species from the South Azorean Seamount Chain
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ponderi, Choristella . . . . . . . . . . . . . . . . . . . . . . . .52
ponsonbyi, Skenea . . . . . . . . . . . . . . . . . . . . . . .72
ponsonbyi, Cyclostrema . . . . . . . . . . . . . . . . . . . . . .72
poseidonae, Ganesa . . . . . . . . . . . . . . . . . . . . . . . .58
pruinosa, Granigyra . . . . . . . . . . . . . . . . . . . . . . .37
rectangularis, Parviturbo . . . . . . . . . . . . . . . . . . . . .69
rehderi, Parviturbo . . . . . . . . . . . . . . . . . . . . . . . .67
Retigyra . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
rhyssa, Vitrinella . . . . . . . . . . . . . . . . . . . . . . . . .48
richardi, Moelleriopsis . . . . . . . . . . . . . . . . . . . .40, 42
richardi, Cyclostrema . . . . . . . . . . . . . . . . . . . . . . .40
rockallensis, Lopheliella . . . . . . . . . . . . . . . . . . . . .61
rolani, Parviturbo . . . . . . . . . . . . . . . . . . . . . . . .67
romettensis, Cirsonella . . . . . . . . . . . . . . . . . . .55, 56, 58
Rugulina . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
scalaroides, Lissotesta . . . . . . . . . . . . . . . . . . . . . . .66
scalaroides, Mikro . . . . . . . . . . . . . . . . . . . . . . . .66
sculpturata, Anekes . . . . . . . . . . . . . . . . . . . . . .27, 36
seamountensis, Parviturbo . . . . . . . . . . . . . . . . . . . .67
Seamountiella . . . . . . . . . . . . . . . . . . . . . . . . .70
serpuloides, Helix . . . . . . . . . . . . . . . . . . . . . . . .72
serpuloides, Skenea . . . . . . . . . . . . . . . . . . . . . . . .74
simile, Cyclostrema . . . . . . . . . . . . . . . . . . . . . . . .26
similis, Akritogyra . . . . . . . . . . . . . . . . . . . . . .25, 26
sinuosa, Homalogyra . . . . . . . . . . . . . . . . . . . . . . .21
sinuosus, Adeuomphalus . . . . . . . . . . . . . . . . . . . . .18
sinuosus, Adeuomphalus . . . . . . . . . . . . . . . .18, 21, 24, 25
Skenea . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Skeneidae . . . . . . . . . . . . . . . . . . . . . . . . . . .55
spirata, Eudaronia . . . . . . . . . . . . . . . . . . . . . .14, 18
supranitidus, Circulus . . . . . . . . . . . . . . . . . . . . . .55
sykesi, “Cyclostrema” . . . . . . . . . . . . . . . . . . . . . . .42
sykesi, Moelleriopsis . . . . . . . . . . . . . . . . . . . . . . .47
tenera, Granigyra . . . . . . . . . . . . . . . . . . . . . . . .37
teriuga, Trenchia . . . . . . . . . . . . . . . . . . . . . . . .53
translucens, Lydiphnis . . . . . . . . . . . . . . . . . . . . . .48
translucens, Xyloskenea . . . . . . . . . . . . . . . . . .48, 52, 55
Trenchia . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Trochaclis . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
umbilisculpta, Anekes . . . . . . . . . . . . . . . . . . . .33, 34
undulisculpta, Anekes . . . . . . . . . . . . . . . . . . . . .27, 36
valentinae, Adeuomphalus . . . . . . . . . . . . . . . . . . . . .24
varisculpta, Anekes . . . . . . . . . . . . . . . . . . . . . . .34
verrilli, Rugulina . . . . . . . . . . . . . . . . . . . . . . . . .5
versiliensis, Trochaclis . . . . . . . . . . . . . . . . . . . . . . .6
versiliensis, Trochaclis . . . . . . . . . . . . . . . . . . .7, 10, 11
weldii, Cirsonella . . . . . . . . . . . . . . . . . . . . . . . .55
wolffi, Trenchia . . . . . . . . . . . . . . . . . . . . . . . . .50
xenos, Xyloskenea . . . . . . . . . . . . . . . . . . . . .48, 50, 51
xenos, Trenchia . . . . . . . . . . . . . . . . . . . . . . .50, 55
xerente, Adeuomphalus . . . . . . . . . . . . . . . . . . . . . .21
Xyloskenea . . . . . . . . . . . . . . . . . . . . . . . . . .47
Iberus, 38 (Suplemento 9), 2020
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