Paralacydonia (Polychaeta: Paralacydoniidae) off Rio de Janeiro, Brazil

Abstract

Paralacydoniids are a small group of burrowing polychaetes, with adults reaching ~10 cm in length. The prostomium is subconical, distally bearing two pairs of frontal appendages; the pharynx is eversible and distally papillate and jaws are absent. The parapodia are biramous, except the first segment which is uniramous. Both rami are widely separated, with long, flattened pre- and post-chaetal lobes, interramal cilia and short digitiform dorsal and ventral cirri. The notochaetae are simple, and the neurochaetae are compound spiniger. The posterior end bears a pair of long cirri. A single species, Paralacydonia paradoxa, has been considered valid. Two other named taxa, Paralacydonia weberi and Paralacydonia mortenseni, are usually considered synonyms of P. paradoxa, although a revision has not been undertaken. Paralacydoniids were collected during the Habitats Project–Campos Basin Environmental Heterogeneity coordinated by CENPES/PETROBRAS, of which the first campaign was held in June–July 2008 and the second campaign in January–February 2009. In all, 289 specimens were observed under the light microscope, and some by means of scanning electron microscopy. The paralacydoniids, collected at depths between 380 and 2514 m, were 0.4 to 19 mm in total length, the largest with 74 chaetigers; the size is related to the number of chaetigers.

Full text

Paralacydonia (Polychaeta:
Paralacydoniidae) off Rio de Janeiro, Brazil
a.e. rizzo and j.r.l. oliveira
Universidade do Estado do Rio de Janeiro, Instituto de Biologia, Departamento de Zoologia, Rua Sa
˜o Francisco Xavier 524,
20511–900, Maracana
˜, Rio de Janeiro, Brazil
Paralacydoniids are a small group of burrowing polychaetes, with adults reaching 10 cm in length. The prostomium is sub-
conical, distally bearing two pairs of frontal appendages; the pharynx is eversible and distally papillate and jaws are absent.
The parapodia are biramous, except the first segment which is uniramous. Both rami are widely separated, with long, flat-
tened pre- and post-chaetal lobes, interramal cilia and short digitiform dorsal and ventral cirri. The notochaetae are simple,
and the neurochaetae are compound spiniger. The posterior end bears a pair of long cirri. A single species, Paralacydonia
paradoxa, has been considered valid. Two other named taxa, Paralacydonia weberi and Paralacydonia mortenseni, are
usually considered synonyms of P. paradoxa, although a revision has not been undertaken. Paralacydoniids were collected
during the Habitats Project–Campos Basin Environmental Heterogeneity coordinated by CENPES/PETROBRAS, of which
the first campaign was held in June–July 2008 and the second campaign in January–February 2009. In all, 289 specimens
were observed under the light microscope, and some by means of scanning electron microscopy. The paralacydoniids, collected
at depths between 380 and 2514 m, were 0.4 to 19 mm in total length, the largest with 74 chaetigers; the size is related to the
number of chaetigers.
Keywords: Paralacydonia paradoxa, continental shelf, Campos Basin, Habitats/Petrobras
Submitted 23 May 2011; accepted 21 July 2011
INTRODUCTION
Paralacydonia is a genus described by Fauvel (1913), and was
initially included in the Phyllodocidae and later transferred to
the subfamily Lacydoniinae, in Phyllodocidae (Fauvel, 1914,
1923, 1953). Hartman (1959) and Hartman & Barnard 1960
considered the genus as belonging to the Lacydoniidae.
Pettibone (1963) established the family Paralacydoniidae to
accommodate the monotypic genus Paralacydonia. For the
establishment of Paralacydoniidae as a separate family,
based on morphological data, Pettibone (1963) noted simi-
larities between paralacidoniids and nephtyids, such as the
parapodia supporting long lamellae, and the well separated
rami with cilia between the notopodium and neuropodium.
This finding persuaded subsequent authors to maintain this
species within the Paralacydoniidae, a position that is main-
tained in this study. Molecular analysis using 18S rDNA
data and 16S rDNA maximum-likelihood strongly supported
a close relationship of the Lacydoniidae with the
Paralacydoniidae (Bo
¨ggemann, 2009).
Only the type species Paralacydonia paradoxa Fauvel, 1913,
described from the Mediterranean, is usually accepted in
Paralacydoniidae. Three other species, Paralacydonia weberi
Horst, 1923, Paralacydonia mortenseni Augener, 1924 and
Paralacydonia paradoxa japonica Kitamori, 1965 were syno-
nymized with P. paradoxa. Uschakov (1958, 1972) considered
both as being the same species. However, no revision has been
done to confirm or reject these proposed synonymies (Blake,
1997), perhaps because of the difficulty in locating the type
material.
Paralacydoniids are small worms that burrow in soft sedi-
ments, and although they inhabit deep water (to 5498 m
depth), they have also been recorded at only 2 m depth
(Kitamori, 1965). Their body is elongated; the first parapo-
dium is uniramous and the following parapodia are biramous.
The notochaetae are simple; the neurochaetae are compound
spinigers usually with one or two simple capillaries.
Paralacydonia paradoxa has been recorded in the Pacific,
including the Indo-Pacific, and the Atlantic Oceans. In the
Atlantic, this species was known from the North Atlantic to
the Gulf of Mexico until 2007, when Rizzo & Amaral (2007)
recorded it for the first time for the South Atlantic Ocean
(Brazil, State of Sa
˜o Paulo). The present report is the first
from the State of Rio de Janeiro.
MATERIALS AND METHODS
The material examined was provided from two campaigns of
the Habitats Project–Campos Basin Environmental
Heterogeneity coordinated by CENPES/PETROBRAS. The
first campaign was carried out from 2 May to 15 July 2008,
and the second from 31 January to 17 March 2009. The
vessel used was RV ‘Emma McCall’. Samples were collected
from different campaigns (HAB3 – 11; 13), Stations (A – I 1 –
11; Cang 6–9; Canac 6 – 9), replicates (1 – 3) and strata
(0–2, 2 – 5 or 5 – 10 cm). The specimens were collected using
box-corers. Polychaetes were sorted from the sediment,
washed and fixed in 4% formol, stored in 70% ethanol and
Corresponding author:
A.E. Rizzo
Email: aerizzo@hotmail.com
1
Marine Biodiversity Records, page 1 of 8. #Marine Biological Association of the United Kingdom, 2011
doi:10.1017/S1755267211000911; Vol. 4; e84; 2011 Published online

then identified. The collection depths ranged between 25 and
3250 m. The material collected was deposited in the
Invertebrate Zoology Laboratory of the State University of
Rio de Janeiro, in the Polychaeta Collection (UERJ).
Measurements and observations were carried out with the
use of a Motic K400 stereomicroscope and an Opton micro-
scope. An LEO 1450VP Carl Zeiss (Oberko
¨chen, Germany)
scanning electron microscope was used to obtain SEM micro-
graphs after the biological material was dehydrated in an
ethanol series: 70%, 80%, 90%, 100% (twice), critical point-
dried with CO
2
using a PELCO CPD 2 critical-point dryer,
and coated with 10 –15 nm gold using a Cressington Sputter
Coater 108.
SYSTEMATICS
PARALACYDONIIDAE Pettibone, 1963
Paralacydonia Fauvel, 1913
(Figures 1–6)
Paralacydonia paradoxa Fauvel, 1913: 54, figure 10; Fauvel,
1923: 198, figure 74e–I; Hartman & Barnard, 1960: 86, plate
Fig. 1. Paralacydonia paradoxa: (A) anterior region, dorsal view; (B) chaetiger 15, anterior view (400×); (C) chaetiger 40, anterior view (400×); (D) pygidium with
three slender anal cirri (400×); (E) pygidium with two slender anal cirri, the third one was lost, and ocellar patches (400×).
2 a.e. rizzo and j.r.l. oliveira

6, figures 1–3; Pettibone, 1963: 184, figure 46; Hartman, 1965:
65; Day, 1967: 350, figure 15.3e – h; Gallardo, 1968: 59, plate
XI, figures 4– 6; Hartman, 1968: 329, figures 1 –3; Uschakov,
1974: 216, plate XXXIV 4–9; Amoureux, 1976: 11; Gathof,
1984: 34-5, figure 34-3a–I; Blake, 1997: 352, figure 14.1;
Redondo & San Martı
´n, 1997: 228, figures 1a– g; Rouse &
Pleijel, 2001: 130–131, figure 31.1 – 31.2; Rizzo & Amaral,
2007: 39, figures 1 – 2.
Paralacydonia weberi Horst, 1923: 221, figures 1 –2; Fauvel,
1953: 129, figure 65e,f; Wilson, 2000: 141 –143, figure 1.81a –e.
Paralacydonia mortenseni Augener, 1924: 311, figure 3a –c;
Augener, 1927: 344.
type species
Paralacydonia paradoxa Fauvel, 1913, by monotypy.
diagnosis
Prostomium conical and elongated, bearing distally two pairs
of bi-articulated cephalic appendages: one dorsal pair of
antennae, and one ventral pair of palps. Muscular pharynx,
unarmed, smooth, distally papillate. First segment achaetous,
appendages absent. First chaetiger with neuropodium only,
following chaetigers biramous, with notopodium and neuro-
podium connected by a ciliated ridge. Parapodium well-
developed, with postchaetal and prechaetal lobes.
Notochaetae simple, capillary; neurochaetae compound,
spiniger.
material examined
Off Rio de Janeiro, Campos Basin – UERJ 0446 (7 specimens):
RV ‘Emma McCall’, box-corer, 3 July 2008, 23837′51.37′′ S
41819′46.78′′W, 390.2 m, Station HAB7, A6, R1, 0–2; UERJ
0452 (3): RV ‘Emma McCall’, box-corer, 3 July 2008,
23837′51.37′′S41819′46.78′′W, 390.2 m, Station HAB7, A6,
R1, 5–10; UERJ 0453 (2): RV ‘Emma McCall’, box-corer, 7
July 2008, 21844′17.18′′S40805′24.22′′W, 402.7 m, Station
HAB7, H6, R2, 5–10; UERJ 0454 (2): RV ‘Emma McCall’,
box-corer, 28 June 2008, 21849′59.01′′ S40806′20.80′′W,
469.4 m, Station HAB7, Canac6, R2, 2–5; UERJ 0455 (1):
RV ‘Emma McCall’, box-corer, 3 July 2008, 23837′52.86′′ S
41819′49.02′′W, 388.9 m Station HAB7, A6, R3, 0 – 2; UERJ
0456 (7): RV ‘Emma McCall’, box-corer, 3 July 2008,
23837′52.75′′S41819′48.91′′ W, 390.6 m, Station HAB7, A6,
R2, 2–5; UERJ 0457 (4): RV ‘Emma McCall’, box-corer, 4
July 2008, 22858′55.87′′S40848′31.98′′W, 386.8 m, Station
Fig. 3. Paralacydonia paradoxa (SEM): (A) anterior end, including
prostomium, cephalic appendages and nuchal organ, dorsal view; (B)
interramal cilia from median parapodium.
Fig. 2. Paralacydonia paradoxa (SEM): (A) anterior and median region,
dorsal view; (B) prostomium, first and second segments, and eversible
pharynx, dorsal view.
paralacydonia off rio de janeiro 3

HAB7, C6, R2, 5–10; UERJ 0458 (17): RV ‘Emma McCall’,
box-corer, 3 July 2008, 23837′51.37′′ S41819′46.78′′W,
390.2 m Station HAB7, A6, R1, 2–5; UERJ 0459 (5): RV
‘Emma McCall’, box-corer, 3 July 2008, 23837′52.75′′ S
41819′48.91′′W, 390.6 m, Station HAB7, A6, R2, 0–2; UERJ
0461 (4): RV ‘Emma McCall’, box-corer, 3 July 2008,
23837′52.86′′S41819′49.02′′ W, 388.9 m, Station HAB7, A6,
R3, 5–10; UERJ 0462 (1): RV ‘Emma McCall’, box-corer, 7
July 2008, 21844′17.11′′S40805′24.26′′W, 401.6 m, Station
HAB7, H6, R3, 5–10; UERJ 0463 (14): RV ‘Emma McCall’,
box-corer, 3 July 2008, 23837′52.86′′ S41819′49.02′′W,
388.9 m, Station HAB7, A6, R3, 2 – 5; UERJ 0464 (7): RV
‘Emma McCall’, box-corer, 4 July 2008, 22858′55.87′′ S
40848′31.98′′W, 386.8 m, Station HAB 7, C6, R2, 2–5; UERJ
0465 (1): RV ‘Emma McCall’, box-corer, 9 July 2008,
22833′31.81′′S40826′45.50′′ W, 396.2 m, Station HAB7, D6,
R2, 2–5; UERJ 0466 (6): RV ‘Emma McCall’, box-corer, 8
July 2008, 22819′05.64′′S40805′48.65′′W, 402.3 m, Station
HAB7, F6, R1, 2– 5; UERJ 0467 (1): RV ‘Emma McCall’, box-
corer, 27 June 2008, 21849′57.87′′ S40806′19.89′′ W, 481.4 m,
Station HAB7, Canac6, R1, 5– 10; UERJ 0468 (1): RV
‘Emma McCall’, box-corer, 4 July 2008, 22858′56.71′′ S
40848′30.96′′W, 399.7 m, Station HAB7, C6, R3, 5–10;
UERJ 0469 (2): RV ‘Emma McCall’, box-corer, 7 July 2008,
21844′17.11′′S40805′24.26′′ W, 401.6 m, Station HAB7, H6,
R3, 2–5; UERJ 0470 (1): RV ‘Emma McCall’, box-corer, 4
July 2008, 22858′55.82′′S40848′31.84′′W, 387.4 m, Station
HAB7, C6, R1, 0–2; UERJ 0471 (2): RV ‘Emma McCall’, box-
corer, 3 July 2008, 23837′52.75′′S41819′48.91′′ W, 390.6 m,
Station HAB7, A6, R2, 5 – 10; UERJ 0472 (7): RV ‘Emma
McCall’, box-corer, 8 July 2008, 22819′06.28′′ S
40805′47.89′′W, 404.6 m, Station HAB7, F6, R3, 5 – 10; UERJ
0473 (3): RV ‘Emma McCall’, box-corer, 8 July 2008,
22819′05.64′′S40805′48.65′′ W, 402.3 m, Station HAB7, F6,
R1, 0–2; UERJ 0474 (4): RV ‘Emma McCall’, box-corer, 11
July 2008, 22833′29.37′′S40826′46.46′′W, 393.4 m, Station
HAB7, D6, R3, 2–5; UERJ 0475 (2): RV ‘Emma McCall’, box-
corer, 4 July 2008, 22858′56.71′′S40848′30.96′′ W, 399.7 m,
Station HAB7, C6, R3, 2 – 5; UERJ 0476 (5): RV ‘Emma
McCall’, box-corer, 8 July 2008, 22819′06.92′′ S
40805′50.44′′W, 403.9 m, Station HAB7, F6, R2, 5 – 10; UERJ
0477 (6): RV ‘Emma McCall’, box-corer, 8 July 2008,
22819′05.64′′S40805′48.65′′ W, 402.3 m, Station HAB7, F6,
R1, 5–10; UERJ 0478 (10): RV ‘Emma McCall’, box-corer, 8
July 2008, 22819′06.92′′S40805′50.44′′W, 403.9 m, Station
HAB7, F6, R2, 2– 5; UERJ 0479 (9): RV ‘Emma McCall’, box-
corer, 8 July 2008, 22819′06.28′′ S40805′47.890′′ W, 404.6 m,
Station HAB7, F6, R3, 2–5; UERJ 0480 (2): RV ‘Emma
McCall’, box-corer, 4 July 2008, 22858′55.82′′ S
40848′31.84′′W, 387.4 m, Station HAB7, C6, R1, 2 – 5; UERJ
0481 (1): RV ‘Emma McCall’, box-corer, 22 May 2008,
22847′08.64′′S39855′28.17′′ W, 2513.9 m, Station HAB4, E11,
R3, 2–5; UERJ 0482 (1): RV ‘Emma McCall’, box-corer, 6
July 2008, 21841′58.41′′S40806′21.70′′W, 404.7 m, Station
HAB7, H6, R1, 5–10; UERJ 0483 (1): RV ‘Emma McCall’,
box-corer, 7 July 2008, 21844′17.11′′ S40805′24.22′′W,
402.7 m, Station HAB7, H6, R2, 2– 5; UERJ 0534 (1): RV
‘Emma McCall’, box-corer, 8 July 2008, 22820′46.35′′ S
40803′44.10′′W, 705.2 m, Station HAB7, F6, R3, 2 – 5; UERJ
1206 (7): RV ‘Emma McCall’, box-corer, 1 February 2009,
23837′45.124′′S41819′53.647′′ W, 400.5 m, Station HAB8, A6
R2, 2–5; UERJ 1207 (2): RV ‘Emma McCall’, box-corer, 5
February 2009, 21844′8.948′′S4085′12.087′′W, 402 m,
Station HAB9, H6, R3, 2–5; UERJ 1208 (3): RV ‘Emma
McCall’, box-corer, 31 January 2009, 22825′45.820′′ S
40817′47.734′′W, 380 m, Station HAB8, E6, R1, 2– 5; UERJ
1209 (10): RV ‘Emma McCall’, box-corer, 31 January 2009,
22858′47.506′′S40848′41.096′′W, 376.6 m, Station HAB8,
C06, R3, 2–5; UERJ 1210 (1): RV ‘Emma McCall’, box-corer,
31 January 2009, 22825′45.820′′ S40817′47.734′′W, 380 m,
Station HAB8, E6, R1, 0–2; UERJ 1211 (10): RV ‘Emma
McCall’, box-corer, 1 February 2009, 23837′44.033′′ S
Fig. 4. Paralacydonia paradoxa (SEM): (A) details of simple notochaetae,
capillary; (B) details of compound neurochaeta, spiniger (upper: blade;
lower: shaft).
Fig. 5. Relation between number of chaetigers and total length.
4 a.e. rizzo and j.r.l. oliveira

41819′50.860′′W, 390.5 m, Station HAB8, A6, R3, 2 – 5; UERJ
1213 (1): RV ‘Emma McCall’, box-corer, 4 February 2009,
21810′59.534′′S40813′4.046′′ W, 683 m, Station HAB9, I7,
R3, 0–2; UERJ 1214 (4): RV ‘Emma McCall’, box-corer, 1
February 2009, 23837′45.124′′ S41819′53.647′′ W, 400.5 m,
Station HAB8, A6, R2, 0– 2; UERJ 1217 (1): RV ‘Emma
McCall’, box-corer, 1 February 2009, 23837′44.087′′ S
41819′54.079′′W, 390.7 m, Station HAB8, A6, R1, 5– 10;
UERJ 1218 (3): RV ‘Emma McCall’, box-corer, 1 February
2009, 23837′44.033′′S41819′50.860′′W, 390.5 m, Station
HAB8, A6, R3, 5–10; UERJ 1221 (2): RV ‘Emma McCall’,
box-corer, 31 January 2009, 22858′47.873′′ S
40848′40.214′′W, 380.6 m, Station HAB8, C6, R1, 5–10;
UERJ 1222 (1): RV ‘Emma McCall’, box-corer, 11 July 2008,
22833′20.763′′S40826′52.631′′W, 393.4 m, Station HAB7,
D6, R3, 0–2; UERJ 1231 (1): RV ‘Emma McCall’, box-corer,
5 February 2009, 21844′8.948′′ S4085′12.087′′W, 402 m,
Station HAB9, H6, R3, 5–10; UERJ 1232 (1): RV ‘Emma
McCall’, box-corer, 5 February 2009, 21844′8.790′′ S
4085′12.005′′W, 405 m, Station HAB9, H6, R1, 2 – 5; UERJ
1233 (3): RV ‘Emma McCall’, box-corer, 10 February 2009,
22818′57.253′′S4085′55.321′′ W, 400 m, Station HAB9, F06,
R3, 0–2; UERJ 1234 (1): RV ‘Emma McCall’, box-corer, 10
February 2009, 22818′57.253′′S4085′55.321′′ W, 400 m,
Station HAB9, F06, R3, 5– 10; UERJ 1236 (5): RV ‘Emma
McCall’, box-corer, 31 January 2009, 22833′22.101′′ S
40826′49.791′′W, 401 m, Station HAB8, D6, R2, 2 –5; UERJ
1237 (2): RV ‘Emma McCall’, box-corer, 7 February 2009,
21849′49.417′′S4086′7.338′′W, 474 m, Station HAB9, Canac
6, R3, 2–5; UERJ 1238 (11): RV ‘Emma McCall’, box-corer,
10 February 2009, 22818′57.253′′S4085′55.321′′ W, 400 m,
Station HAB9, F6, R3, 2–5; UERJ 1239 (4): RV ‘Emma
McCall’, box-corer, 1 February 2009, 23837′45.124′′ S
41819′53.647′′W, 400.5 m, Station HAB8, A6, R2, 5– 10;
UERJ 1240 (2): RV ‘Emma McCall’, box-corer, 7 February
2009, 21849′50.119′′S4086′8.332′′ W, 476 m, Station HAB9,
Canac 6, R1, 5–10; UERJ 1241 (2): RV ‘Emma McCall’, box-
corer, 1 February 2009, 23837′44.087′′S41819′54.079′′ W,
390.7 m, Station HAB8, A06, R1, 0– 2; UERJ 1242 (1): RV
‘Emma McCall’, box-corer, 31 January 2009, 22825′46.389′′ S
40817′45.725′′W, 387.1 m, Station HAB8, E6, R3, 0 –2; UERJ
1244 (5): RV ‘Emma McCall’, box-corer, 4 February 2009,
21813′25.522′′S40815′10.531′′W, 417 m, Station HAB9, I06,
R1, 5–10; UERJ 1245 (1): RV ‘Emma McCall’, box-corer, 9
July 2008, 22833′23.203′′S40826′51.671′′W, 396.2 m, Station
HAB7, D6, R2, 0–2; UERJ 1246 (7): RV ‘Emma McCall’, box-
corer, 31 January 2009, 22825′46.389′′ S40817′45.725′′W,
387.1 m, Station HAB8, E6, R3, 2 – 5; UERJ 1247 (2): RV
‘Emma McCall’, box-corer, 31 January 2009, 22833′22.234′′ S
40826′49.928′′W, 400 m, Station HAB8, D06, R1, 2–5; UERJ
1248 (4): RV ‘Emma McCall’, box-corer, 31 January 2009,
22818′50.882′′S4085′41.019′′W, 386 m, Station HAB8, F6,
Fig. 6. Distribution records of Paralacydonia paradoxa.
paralacydonia off rio de janeiro 5

R2, 0–2; UERJ 1249 (11): RV ‘Emma McCall’, box-corer, 1
February 2009, 23837′44.087′′ S41819′54.079′′ W, 390.7 m,
Station HAB8, A6, R1, 2– 5; UERJ 1250 (1): RV ‘Emma
McCall’, box-corer, 31 January 2009, 22833′22.234′′ S
40826′49.928′′W, 400 m, Station HAB8, D06, R1, 0–2; UERJ
1251 (1): RV ‘Emma McCall’, box-corer, 31 January 2009,
22858′47.873′′S40848′40.214′′W, 380.6 m, Station HAB8,
C6, R1, 2–5; UERJ 1252 (1): RV ‘Emma McCall’, box-corer,
31 January 2009, 22825′46.389′′S40817′45.725′′ W, 387.1 m,
Station HAB8, E6, R3, 5 – 10; UERJ 1253 (1): RV ‘Emma
McCall’, box-corer, 31 January 2009, 22858′47.873′′ S
40848′40.214′′W, 380.6 m, Station HAB8, C6, R1, 0–2;
UERJ: 1254 (3): RV ‘Emma McCall’, box-corer, 7 February
2009, 21849′49.453′′S4086′8.116′′ W, 474.8 m, Station HAB9,
Canac 6, R2, 5–10; UERJ 1255 (1): RV ‘Emma McCall’, box-
corer, 10 February 2009, 22826′48.264′′ S40810′6.916′′ W,
700.7 m, Station HAB9, E7, R3, 0 – 2; UERJ 1256 (2): RV
‘Emma McCall’, box-corer, 31 January 2009, 22858′47.668′′ S
40848′38.325′′W, 393.6 m, Station HAB8, C06, R2, 2–5;
UERJ 1257 (9): RV ‘Emma McCall’, box-corer, 1 February
2009, 23837′44.033′′S41819′50.860′′W, 390.5 m, Station
HAB8, A6, R3, 0–2; UERJ 1258 (1): RV ‘Emma McCall’, box-
corer, 31 January 2009, 22825′45.849′′ S40817′45.934′′ W,
385 m, Station HAB8, E6, R2, 2– 5; UERJ 1259 (5): RV
‘Emma McCall’, box-corer, 31 July 2009, 22858′47.506′′ S
40848′41.096′′W, 376.6 m, Station HAB8, C06, R3, 0–2;
UERJ 1260 (4): RV ‘Emma McCall’, box-corer, 5 February
2009, 21844′8.790′′S4085′12.005′′ W, 405 m, Station HAB9,
H6, R1, 5–10; UERJ 1261 (1): RV ‘Emma McCall’, box-corer,
30 January 2009, 22818′49.424′′S4085′39.500′′ W, 383.8 m,
Station HAB8, F6, R1, 5–10; UERJ 1262 (6): RV ‘Emma
McCall’, box-corer, 31 January 2009, 22818′49.424′′ S
4085′39.500′′W, 383.8 m, Station HAB8, F06, R1, 2 –5; UERJ
1263 (3): RV ‘Emma McCall’, box-corer, 5 February 2009,
21844′8.689′′S4085′6.317′′W, 404 m, HAB9, H6, R2, 0 – 2.
description
Two hundred and fourteen complete specimens, body ranging
from 1.5–18 mm in length and from 0.1– 0.7 mm in width,
reaching 74 chaetigers; the size is related to the number of
chaetigers (Figure 5). Body whitish on smaller specimens, yel-
lowish on largest ones when preserved in ethanol (Figure 1A).
Small brownish points scattered on prostomium and along
body, including parapodia (Figure 1A – C). Body elongated,
slender (Figure 2A). Prostomium subconical, wider than
long; oblong in adult. Pair of antennae located dorsally on
distal part of prostomium, and pair of short, ventrally posi-
tioned palpi on end of prostomium; both bi-articulated
(Figure 2B). Median antenna absent. Pair of nuchal organs
as small knobs located laterally on prostomium (Figure 3A).
Small eyes, subdermal, located in dorsal region between pros-
tomium and peristomium; eyes seen by transparency in juven-
iles. Peristomium slightly fused to prostomium, involved or
restricted ventrally to the mouth. Pharynx muscular, cylindri-
cal, distally composed by nine soft conical papillae, these of
same size (Figure 2B); jaw and paragnaths absent. First
segment achaetous and without cirri (Figure 2B). Second
segment (¼first chaetiger) uniramous with neuropodia and
neurochaetae (Figure 2B); following segments biramous.
Notopodium approximately 1/3 shorter than neuropodium.
Noto- and neuro-podia supported by an acicula and con-
nected by a ciliated ridge (Figure 3B). Parapodia more
slender and longer toward posterior region, composed of
pre- and post-chaetal lamellae, both incised in the median
portion and directed toward the inter-ramal region
(Figure 1B, C). Prechaetal lamellae shorter than postchaetal
lamellae; postchaetal lamellae slightly rounded on basal
portion, becoming conical distally. Four to 14 notochaetae
simple, capillary, with a face bearing transverse row of
minute spines (Figure 4A). Neurochaetae predominantly spi-
niger, from 6 to 19, articulation of heterogomph type, with
shaft fringed (Figure 4B); one or two simple, marginally spinu-
late neurochaetae may be present on the inferior position of
the neuropodial fascicles. Dorsal and ventral cirri, both digiti-
form, ventral cirrus almost three times the size of dorsal cirrus
(Figure 1B, C). Pygidium bulbous, slightly rounded, with three
slender anal cirri, including pair of long cirri in lateral position
and single short cirrus (1/6 length of lateral cirri) in central
position (Figure 1D); single anal cirrus, when present, posi-
tioned above lateral cirri (usually lost in adult specimens).
Juvenile specimens have two ocellar patches on pygidium
(Figure 1E).
geographical distribution
Circumtropical (Figure 6). Pacific Ocean: from California to
southern Ecuador; Indo-Pacific: Japan, Yellow Sea, Tonkin
Gulf, Nha Trang (Vietnam), Indonesia, south-east Australia,
New Zealand, Mozambique; Mediterranean: Monaco (type
locality), San Antonio and Valencia (Spain), Morocco;
Atlantic Ocean: New England (Massachusetts), Gulf of
Mexico, and Brazil (off States of Rio de Janeiro, Sa
˜o Paulo
and Parana
´). At depths from 2 to 5498 m.
DISCUSSION
The type locality of Paralacydonia paradoxa is south of
Monaco (Mediterranean), between 48 and 52 m depth. The
holotype was not designated from any of the three specimens
collected (Fauvel, 1913: 55). The species was recorded for the
first time in the South Atlantic (south-eastern Brazil) from
depths of 156 to 400 m by Rizzo & Amaral (2007). Because
the comparison is based on phenotypic characters, this
species has been considered eurybathic, having been recorded
from 2 to 5498 m, with a circumtropical distribution and
incursions into temperate waters (Figure 6). However,
recent genetic studies of other polychaete families have
pointed to complexes of cryptic species (e.g. Westheide &
Hass-Cordes, 2001; Westheide & Schmidt, 2003).
In the absence of genetic studies of paralacydoniids across
wide geographical and bathymetric ranges, the purpose of this
study is to quantify morphological characters from a restricted
area. The specimens from off Rio de Janeiro show similarities
to earlier descriptions of P. paradoxa. The size seems to be
related to the number of chaetigers (Figure 5). However,
some small differences between the present material and
other descriptions can be noted. Comparing SEM images
revealed differences in relation to the nuchal organ and its
position on the prostomium. In the specimens examined
here, a pair of nuchal organs that are present as small, slightly
inflated knobs located laterally on the prostomium were
clearly seen; whereas Rouse & Pleijel (2001: figure 31.2b)
found, in addition to a lateral pair, possibly a second pair, in
a lateral depression on the posterior side of the prostomium.
The prostomial appendages have generated controversy
among researchers, having been sometimes called antennae
6 a.e. rizzo and j.r.l. oliveira

(Fauvel, 1913; Hartman & Barnard, 1960; Pettibone, 1963;
Hartman, 1965, 1968; Day, 1967; Gallardo, 1968; Blake,
1997; Redondo & San Martı
´n, 1997) or cephalic appendages
or tentacles (Fauvel, 1923; Uschakov, 1974), and so may
cause noise when used in analyses to try to establish the phy-
logenetic position of paralacydoniids in relation to other poly-
chaete families. Nowadays, the presence of a dorsal pair of
antennae and a pair of ventral palpi is well accepted
(Wilson, 2000; Rouse & Pleijel, 2001). Palps are homologous
structures that are largely supported in cladistic analyses,
including paralacydoniids (Rouse & Fauchald, 1997) and did
not change. An issue that still needs to be resolved is related
to the peristomium: whether it is limited only to the ventral
side of mouth (Rouse & Pleijel, 2001), or whether it also sur-
rounds the mouth dorsally.
The presence of small subdermal eyes was noted in both
juveniles and adults. Small eyes were also noted by Day
(1967), Gathof (1984) and Redondo & San Martin (1997),
but were not reported in other studies (Fauvel, 1953;
Hartman & Barnard, 1960; Hartman, 1965; Gallardo, 1968;
Uschakov, 1974; Blake, 1997; Wilson, 2000).
The chaetae have not been examined in detail by earlier
authors, and it is possible that they may show differences.
Observations based on optical microscopy have indicated
the presence of simple capillary notochaetae and compound
spiniger neurochaetae. However, details seen only by means
of SEM, such as transverse rows of minute spines located on
the inferior face of the capillary chaetae and the presence of
a fringe on the basal article of the spinigers, are characters
that have been insufficiently observed.
Although a median papilla was mentioned by Rouse &
Pleijel (2001), it has not been observed in our specimens. It
is possible that the median papilla mentioned by these
authors is the scar of insertion of the third cirrus located cen-
trally. We observed a third anal cirrus, about 1/6 the length of
the lateral pair; a similar third cirrus was reported by Gallardo
(1968: 59). This structure cannot be considered a papilla,
because it is not a short rounded protuberance, but
rather resembles one of the lateral cirri, only shorter.
However, this third cirrus is usually lost in adult specimens
(Pettibone, 1963). Other authors have mentioned only a
pair of long anal cirri (Uschakov, 1974: figure 8; Blake,
1997; Redondo & San Martı
´n, 1997; Wilson, 2000; Rizzo &
Amaral, 2007).
These and other morphological characters, along with mol-
ecular studies, will be required to confirm or reject the hypoth-
esis that P. paradoxa may be a single species with intraspecific
variations, or a complex of cryptic species.
ACKNOWLEDGMENTS
This study was coordinated by CENPES/PETROBRAS
through the Habitats Project– Campos Basin Environmental
Heterogeneity. Our thanks to PETROBRAS for making it
possible to collect and analyse the biological material. We
appreciate the use of facilities and assistance at the
Department of Zoology, Institute of Biology, State
University of Rio de Janeiro (UERJ). Our thanks also to the
Laborato
´rio de Microscopia Eletro
ˆnica: Professor Luiz
Henrique Monteiro Leal, Instituto de Biologia Roberto
Alca
ˆntara Gomes (IBRAG), and also to Alan Cesar Nunes
de Moraes for support with the SEM images. Thanks to
Robin Wilson and Markus Bo
¨ggemann for helpful comments
and suggestions. Janet W. Reid revised the English text.
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Correspondence should be addressed to:
A.E. Rizzo
Universidade do Estado do Rio de Janeiro
Instituto de Biologia
Departamento de Zoologia
Rua Sa
˜o Francisco Xavier 524, 20511–900
Maracana
˜, Rio de Janeiro, Brazil
email: aerizzo@hotmail.com
8 a.e. rizzo and j.r.l. oliveira