On a supposed new species of Quasimitra (Gastropoda: Mitridae: Mitrinae) recently described from Indonesia: The birth of a new synonym.

Abstract

The newly described species Quasimitra houarti Dharma, 2021 from Indonesia is found to be a junior synonym of Quasimitra stossieri (Herrmann, 2016).

Full text

Volume: 54 THE FESTIVUS ISSUE 1
ISSN 0738-9388
3
On a supposed new species of Quasimitra (Gastropoda: Mitridae: Mitrinae)
recently described from Indonesia: The birth of a new synonym
Aart M. Dekkers, Oasestraat 79, 1448 NR Purmerend, the Netherlands
Aart.dekkers@wxs.nl
ABSTRACT The newly described species Quasimitra houarti Dharma, 2021 from Indonesia is
found to be a junior synonym of Quasimitra stossieri (Herrmann, 2016).
KEY WORDS Mitridae, Quasimitra,Q. houarti,Q. stossieri, Sumbawa, Indonesia
INTRODUCTION
A new species of Quasimitra,Q. houarti, was
described by Dharma (2021), based on six
specimens collected by a local diver from
depths of 25-30 m, off Bungin Island,
Northwest of Sumbawa Island, Nusa Tenggara
Islands, Indonesia. Another specimen from the
Sofjan Effendy Collection, dead collected,
approximately twenty years ago, from Nusa
Tenggara Islands, Indonesia (Dharma, 2021)
was included in that paper. The new species was
compared in the descriptive paper with
Quasimitra nubila (Gmelin, 1791), Q. lamarckii
(Deshayes, 1832), and Q. hawaiiensis (Kay,
E.A., 1979).
Herrmann (2016) reviewed part of the genus
(then still contained in Mitra Lamarck, 1798)
and described a new species, Mitra stossieri
Herrmann, 2016, from Indonesia, type locality:
Indonesia, Bali, Sanur. Herrmann, 2016 gives
the range from Bali and the Flores Sea in
Indonesia, to the Solomon Islands and Tonga,
and he illustrated the shells from the various
localities: Paratype 1, Tonga, Vava´u, Umunak,
37.6 mm; Paratype 2, Solomon Islands, Marau,
Guadalcanal, 50.3 mm; Paratype 6, Indonesia,
Flores Sea, north side of Kaledupa Island, 34.3
mm.
I refer to Hermann (2016) for the plates
containing other related species in this group:
Mitra propinqua (A. Adams, 1853) and Mitra
brettinghami E. A. Smith, 1906. Fedosov et al.
(2018) include many other species in the (then
newly erected) genus Quasimitra.The
description of Quasimitra was based on only
three species in the Bayesian phylogenetic tree
of Mitridae (Fedosov et al., figure 5): Mitra
sophiae Crosse, 1862; Mitra puntulata Lamarck,
1811; and, Mitra sanguinolenta Lamarck, 1811.
The shells of the aforementioned three species
do not have much in common with the herein
restricted group of species, which is unnamed as
of yet. In a following paper I will address this
group of related species with descriptions of a
new genus and new species in this species
complex.
ABBREVIATIONS
MZB Museum Zoologicum Bogoriense,
Cibinong, Bogor, Indonesia
ZSM Zoologische Staatssammlung München,
Munich, Germany
MH Collection of Manfred Herrmann,
Rosdorf, Germany
GS Collection of Günter Stossier, Hamburg,
Germany
ARN Collection of Armen Rizal Ngo, Jakarta,
Indonesia

Volume: 54 THE FESTIVUS ISSUE 1
ISSN 0738-9388
4
SYSTEMATICS
Family: Mitridae Swainson, 1831
Subfamily: Mitrinae Swainson, 1831
Genus: Quasimitra Fedosov, Herrmann, Kantor
& Bouchet, 2018
Quasimitra stossieri (Herrmann, 2016).
Proposed Synonym: Quasimitra houarti
Dharma, 2021
Original description of Q. stossieri: “Shell
solid, slender fusiform, medium sized, reaching
53.3 mm in length; width 30-36 % of length.
Only fragments of white, glassy protoconch
present. Teleoconch consists of 7 to 8 slightly
convex whorls. Suture well defined but not deep.
Straight outline of spire. All whorls smooth and
completely covered with fine spiral grooves,
dissected by minute axial threads. 8 to 9 spiral
grooves on penultimate and 32 to 40 grooves on
body whorl. Aperture equal in length to the
spire, narrow and lanceolate. In adult specimen
outer lip thickened, crenulated, and rounded
with a more straight posterior part. Columella
with 5 well-defined oblique folds of nearly
equal strength. Callus layer moderately thin, but
well defined. Siphonal canal slightly shorter
than outer lip, almost straight with a small
dorsal notch. Colour pattern, whitish to cream
shell with 2 to 4 dark brown axial streaks on
every whorl with darker area at the suture, not
directly continued on next whorl, on body whorl
ending one third before anterior end. At shell
periphery large light blotches on the cream
background between the streaks. On body whorl
a few fine, nearly invisible white dots are
existent which are nearly absent on penultimate
or earlier whorls. Tips of crenulated lip dotted
brown. Those fine brown dots are sometimes
also present on axial lines on body and earlier
whorls together with a slight axial groove,
looking like a secondary lip. Aperture cream
white.”
Original description of Q. houarti: “Shell of
average size for genus, height up to 58.5 mm,
thick, elongate ovate, spire rather tall and
tapering to apex, last whorl large. In all material
examined the protoconchs were missing, adult
shells averaging 9-10 whorls; spire whorls
almost flat or somewhat convex, more convex
towards the last whorl, and last whorl slightly
inflated; suture shallow, crenulated by
termination of radial ribs; base color white, with
irregular light brown and brown streaks, and
small scattered white spots; streaks reach suture;
some earlier whorls whitish; body whorl with
three light brown spiral bands, first above
aperture posterior, the third vague near bottom
above siphonal fasciole, and the second between
those two bands; shell sculptured with 28-44
spiral grooves and intersecting with radial striae
or microscopic radial ribs; aperture elongate,
oblique, angulated posteriorly, slightly inflated
at the bottom, height of aperture slightly longer
than half of the shell height; inside of aperture
smooth, white; outer lip thickened, glossy,
terminating in brown denticles at end of spiral
grooves; columella overlaid with white callus,
with 5-6 oblique folds; umbilicus closed;
siphonal canal slightly recurved, siphonal
fasciole sculptured with oblique spiral cords,
siphonal notch open.”
Besides the difference in style of describing the
aspects of the shells, the major differences are
set out in Table 1. It seems the shells of Q.
houarti are slightly longer and slimmer than
those of Q. stossieri. The type localities of both
holotypes are roughly 150 km apart, with the
Island of Lombok in between. Paratype 1 and 5
of Q. stossieri show the same slenderness of the
shells depicted by Dharma. As these differences
are minor, they fall within the species variability.

Volume: 54 THE FESTIVUS ISSUE 1
ISSN 0738-9388
5
Table 1. Noted differences in the descriptions of Q. stossieri and Q. houarti.
CONCLUSION
The conclusion is that Q. houarti is a junior
synonym of Q. stossieri. Because Q. houarti has
an entry in the WoRMS database as an accepted
species, rather it was appropriate to recognize Q.
houarti as in synonymy.
Describing new species is not an easy job, and
one requires a knowledge of the species
variability, range, and a thorough review of
relevant literature. Being up to date with
literature is critical with the many new species
described every year. Relying on older books is
a pitfall for species identification. Often popular
books copy the faults from other (older) popular
books and the errors continue. Unfortunately,
Dharma (2021), a well-respected author, as well
as the reviewer of his article must have
overlooked the publication of Herrmann (2016).
ACKNOWLEDGEMENTS
Günter Stossier, Hamburg, Germany, is thanked
for the photos of the paratypes of Mitra stossieri
Herrmann, 2016 used for the plate. The
holotype is under copyright of the Zoologische
Staatssammlung München and therefore could
not be used in this paper. Other specimens used
in the plate are from Armen Ngo Collection,
taken from the same population as holotype,
which was used to describe Q. houarti.
LITERATURE CITED
Dharma, B. 2021. A new species of Quasimitra
(Gastropoda: Mitridae: Mitrinae) from
Indonesia. The Festivus 53(2):142-144.
https://doi.org/10.54173/F532142
Fedosov A., N. Puillandre, M. Herrmann, Y.
Kantor, M. Oliverio, P. Dgebuadze, M.V.
Modica & P. Bouchet. 2018. The collapse
of Mitra: molecular systematics and
morphology of the Mitridae (Gastropoda:
Neogastropoda). Zoological Journal of the
Linnean Society. 183(2):253-337.
https://doi.org/10.1093/zoolinnean/zlx073
Herrmann, M. 2016. A new Mitra species
(Gastropoda: Mitridae) from the Central
Indopacific. Conchylia 47(3-4):17-24.
https://doi.org/10.15468/39omei
Q. stossieri
Q. houarti
Shell length
Reaching 53.3 mm
Height up to 58.5 mm
Form
Slender fusiform
Elongate ovate
Number of whorls
Teleoconch consists of 7 to 8
slightly convex whorls = 8-9
whorl in total
Adult shells averaging 9-10
whorls.
Sculpture on body whorl
32 to 40 grooves
28-44 spiral grooves
Columella
Columella with 5 well-
defined oblique folds of
nearly equal strength.
Callus layer moderately thin,
but well defined.
With 5-6 oblique folds.
Columella overlaid with
white callus.
Origin of holotype
Bali, Sanur
Bungin Island, northwest of
Sumbawa Island, Nusa
Tenggara Islands

Volume: 54 THE FESTIVUS ISSUE 1
ISSN 0738-9388
6
Additional Reading:
Cernohorsky, W.O. 1976. The Mitridae of the World.
Part I. Subfamily Mitrinae. Indo-Pacific Mollusca
3(17) 273-528, pls. 248-466.
Dharma, B. 2005. Recent & Fossil Indonesian Shells.
ConchBooks, Hackenheim. 424 pp., 150 pls., 48 figs.
Pechar, P., C. Prior & B. Parkinson 1981. Mitre Shells
from the Pacific and Indian Ocean. Robert Brown
and Associates Pty. Ltd., Bathurst, N. S. W. 130 pp.,
56 pls., figs.
Poppe, G.T. & S.P. Tagaro. 2006. New Mitridae and
Costellariidae from the Philippines and the East
China Sea. Visaya 1(6):76-89.
Reeve, L. 1844. Conchologia Iconica. Monograph of the
Genus Mitra. 29 pls. London (Reeve). Unpaginated.
Robin, A. & J. C. Martin. 2004. Mitridae –
Costellariidae. 34 pp., 64 pls. Hackenheim
(ConchBooks).
Thorsson, W. & R. Salisbury. 2001. Living Mitridae,
Chapter Mitra, Part 5. Internet Hawaiian Shell News,
May 2001:25-34.
Thorsson, W. & R. Salisbury. 2009a. Living Mitridae,
Chapter Mitra, Part 18a. Internet Hawaiian Shell
News, July 2009:9-22.
Thorsson, W. & Salisbury, R. 2009b. Living Mitridae,
Chapter Mitra, Part 20. – Internet Hawaiian Shell
News, September 2009:3-7.
Cite as: Dekkers, A.M. 2022. The newly described species
Quasimitra houarti Dharma, 2021 from Indonesia is found to be
a junior synonym of Quasimitra stossieri (Herrmann, 2016).
The Festivus 54(1):3-6.
http://doi.org/10.54173/F5413
Plate 1. Quasimitra stossieri (Hermann, 2016)
1= Paratype 2, Solomon Islands, Marau, Guadalcanal, 50.3 mm, MH; 2= Paratype 1, Tonga, Vava´u, Umunak, 37.6 mm, GS; 3=
Paratype 6, Indonesia, Flores Sea, north side of Kaledupa Island, 34.3 mm, immature, GS. 4= Indonesia, Bungin Island, northwest of
Sumbawa Island, 51.9 mm, ARN; 5= Indonesia, Bungin Island, Northwest of Sumbawa Island, 27.7 mm, immature specimen, ARN.