Bull. Natl. Mus. Nat. Sci., Ser. A, Suppl. 6, pp. 51–58, March 30, 2012

A New Deep-sea Eelpout, Pachycara moelleri(Perciformes: Zoarcidae) from Japan
Gento Shinohara
Department of Zoology, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki 305–0005, Japan
E-mail: s-gento@kahaku.go.jp

Abstract A new zoarcid ¿sh, Pachycara moelleri, is described from a single 318 mm specimen
collected from off Kii Peninsula, Japan in 4,093 m. The new species is distinguished from its congeners in having following characters: vertebrae 31＋78＝109; lateral line con¿guration withmediolateral branch originating at posterior quater of trunk; pelvic ¿ns absent; palatine teeth in
two rows; no pseudobranch ¿laments; tricuspid and bicupsid rakers present on ¿rst gill arch; interorbital space wide; nostril tube short, not reaching to upper lip; branchiostegal rays 7; suborbital
pores 6, postorbital pores 2 (positions 1 and 4), preoperculomandibular pores 8 (4＋4); whitish
horseshoe-shaped blotches on dorsal ¿n. This record is the ¿rst occurrence of Pachycara from theWestern North Paci¿c.
Key words: Abyssal zone, Deep-sea ¿shes, Kii Peninsula, New species, Western North Paci¿c.

The zoarcid genus Pachycara Zugmayer, 1911
includes 24 deep-sea species, all inhabiting theupper bathyal to abyssal zones (Anderson andFedorov, 2004; Anderson, 2006; Møller andKing, 2007). The species of Pachycara havebeen described and/or reported from the Atlantic,
Indian, southwestern and eastern Paci¿c, andSouthern oceans. No specimens of Pachycara
have been collected from the Western North
Paci¿c.
In 2008, one specimen of a species belonging
to Pachycara was collected from the abyssal
zone of the Paci¿c side of Japan during a deepsea organism survey made by the R/V Soyo-maruof the National Fisheries Research Institute. This
species is similar to some known species fromthe Indian Ocean in its lateral line con¿guration,lack of pelvic ¿ns and/or absence of pseudobranch ¿laments. The new species differs fromits congeners in having unique lateral line con¿guration and is described here as new to science.
Materials and Methods
Methods for taking counts and measurements

follow Peden and Anderson (1978) and Anderson(1982). Vertebrae and other osteological elements were examined from radiographs andcomputed tomography. Terminology of head
pores follows Anderson (1994). Total length(TL), standard length (SL), and head length (HL)
are used throughout. Gill raker shape was examined by the versatile staining with Cyanine Blue
(Saruwatari et al., 1997).
The specimen is deposited in the Department
of Zoology, National Museum of Nature and Science, Tsukuba (NSMT).
Pachycara Zugmayer, 1911
(New Japanese name: Bouzugenge-zoku)

Remarks. The latest diagnosis of the genus
was proposed by Anderson (1994) as follows:
suborbital bones 6–8, canal with 5–7 pores; submental crests absent; parasphenoid wing below
mid-height of trigeminofacial foramen; palatopterygoid series well developed; Àesh ¿rm; scales,
pyloric caeca, lateral lines, vomerine and palatine
teeth present; pseudobranch ¿laments, and pelvic¿ns present or absent; vertebrae 21–32＋67–94＝

52

G. Shinohara

93–122. When Geistodoerfer (1994) originallydescribed Pachycara thermophilum from the
Mid-Altantic Ridge, he incorrectly diagnosed
this species as having no lateral lines on the body(see Anderson and Bluhm, 1996). On the other
hand vertebral number should be slightly broadened to 21–34＋67–94＝93–123 by the recent
discovery of Pachycara saldanhai Biscoito andAlmeida, 2004.
Anderson (1989) noted that Pachycara may beclosely related to Lycodes Reinhardt, 1831 phylogenetically and gave as example one apomorphic character (＝reduced parasphenoid wing)
and three plesiomorphic characters, i.e., retentionof oral valve, retention of small head pores, andlack of submental crests. Møller and Anderson(2000) demonstrated morphological differencesamong Lycenchelys Gill, 1884, Lycodes, andPachycara. Although it is possible to separate
Pachycara by external characters (e.g., no submental crests, head pores not well developed)from its close congeners, the monophyly andphylogenetic position are thought to be still inquestion. More anatomical and molecular data on
species of Pachycara are strongly needed toresolve these problems.
Importantly, for identi¿cation of species ofPachycara, gill raker morphology and lateral linecon¿guration were shown to be highly valuable(Anderson, 1989, 1994).
The new Japanese name comes from the wordthat appears in each of the three Japanese names
proposed by Nakaya et al. (2009) for eelpout
specimens collected off Peru during a joint Japanese-Peruvian trawl survey 1998–2003.
Pachycara moelleri sp. nov.
(New Japanese name: Souyou-bouzugenge)(Figs. 1–5, Table 1)

Holotype. NSMT-P 105631, female, 312.0 mm
SL (318.0 mm TL), Paci¿c off Kii Peninsula,
Wakayama, Honshu, Japan (32°0.7ƍN, 135°57.2ƍE–
32°0.3ƍN, 136°2.7ƍE), 4,093 m, 5 August 2008,
crab trap “Kanikago” (＝crab baskets), R/V
Soyo-maru, coll. by K. Fujimoto and M. Okanishi.
Diagnosis. Vertebrae 31＋78＝109; lateralline con¿guration with mediolateral branch originating at posterior quarter of trunk; pelvic ¿ns

Fig. 1. Fresh condition (top), formalin ¿xed condition (middle), and drawing (bottom) of Pachycara moelleri sp. nov.,
holotype, NSMT-P 105631, female, 312.0 mm SL.

New Deep-sea Eelpout from Japan

Fig. 2. Gill rakers on ¿rst gill arch (right side) ofPachycara moelleri sp. nov., holotype, NSMT-P
105631, female, 312.0 mm SL. Upper, distribution
three types of gill rakers; lower, magni¿ed squarepart with white dot lines in upper ¿gure. Stainedby Cyanin Blue. Bar＝1 mm.

absent; palatine teeth in two rows; no pseudobranch ¿laments; tricuspid and bicupsid gill rakers present on ¿rst arch; interorbital space wide;
nostril tube short, not reaching to upper lip; branchiostegal rays 7; suborbital pores 6, postorbital
pores 2 (positions 1 and 4), and preoperculomandibular pores 8 (4＋4); whitish horseshoe-shaped
blotches on dorsal ¿n.
Description. Counts and measurements areshown in Table 1. Flesh ¿rm, not gelatinous (Fig.
1). Body moderately elongate; trunk robust, taillaterally compressed. Head ovoid, robust. Snout
broad, rounded, anterior pro¿le vertical. Eye
small, almost rounded, not reaching dorsal pro¿le of head. Interorbital space broad, its width
more than half of snout length. Mouth subterminal; upper lip continuous across snout; lower lip
with thin labial lobe. Upper jaw not protruding,

53

Fig. 3. Head pores of Pachycara moelleri sp. nov.,
holotype, NSMT-P 105631, female, 312.0 mm SL.

extending posteriorly to middle of eye. Nasal
tube very short, not reaching upper lip. Gill slit
extending ventrally and reaching base of 17th
pectoral ¿n ray. Opercular lobe at dorsal marginof gill slit developed. Tricupsid, bicupsid andsingle-tip gill rakers on ¿rst arch (Fig. 2). Branchiostegal rays 7. Upper origin of pectoral ¿n atlevel of body midheght. Pelvic ¿ns absent.
Jaw, vomer and palatine teeth small, conical.
Premaxilla with two rows of teeth anteriorly andsingle row posteriorly. Dentary with 4–5 rows ofteeth anteriorly blending to single row posteriorly. Vomerine teeth in irregular patch. Palatine
teeth in 2 rows.
Head pores developed (Fig. 3). Postorbital
pores 2, located at positions 1 and 4 (sensu

54

G. Shinohara
Table 1. Comparison of meristic and morphometric characters among species of Pachycara with 3 rows bodyneuromasts.
P. moelleri sp. nov.

Counts
Dorsal ¿n rays
Anal ¿n rays
Pectoral ¿n rays
Caudal ¿n rays
Precaudal vertebrae
Caudal vertebrae
Total vertebrae
First dorsal ¿n pterygiophore associated with vertebra
Last precaudal vertebra associated with dorsal ¿n ray
Gill rakers
Pseudobranch ¿laments
Dentition
Teeth on premaxilla
Teeth on vomer
Teeth on palatine
Teeth on dentary% SL
Head length
Head width
Head height
Snout length
Nostril tube length
Eye diameter
Pupil diameter
Interorbital width (hard)
Upper jaw length
Lower jaw length
Preanal length
Predorsal length
Dorsal ¿n height above anal ¿n origin
Body height at anal ¿n origin
Pectoral ¿n length
Pectoral ¿n base height
Gill slit length
Opercular lobe length
Isthmus width%HL
Head width
Upper jaw length
Pectoral ¿n length
Snout length
Eye diameter
Interorbital width
Pectoral base/length ratioab

P. andersonia

P. shcherbachevia

Holotype

n＝31

n＝2

312 mm SL

123–250 mm SL

236–272 mm SL

103
83
19b
12
31
78
109
7
28
15
0

92–97
76–80
18–20
12
24–26
73–77
98–102
5–6
20–23
16–17
3–4

112
94
16
12
29–32
90–91
120
7
24
16
3

19–20b1018b39–40b

9–18
4–8
5–8
16–26

13–27
2–6
3–4
14

14.7
8.7
11.2
4.1
0.7
1.8
1.1
2.4
5.3
7.6
44.0
22.4
1.9
13.9
10.9
5.2
6.2
0.9
7.0

15.9–18.9
8.0–13.4
9.5–12.1
4.4–5.4
0.6–1.0
2.0–3.7
1.5–2.2
1.1–1.9
6.1–7.9
5.6–7.6
37.2–44.3
18.6–23.0
2.7–3.7
8.9–12.7
12.0–15.5
4.1–5.4
5.2–6.5
0.7–1.3
3.9–7.3

11.4–12.0
7.7–7.8
7.2
3.5
0.5
1.7
1.0
1.2
4.6–4.8
4.0–4.3
34.0
16.6–20.6
N/A
7.7–8.1
9.2–10.0
2.6
4.6
0.8
4.4

59.2
36.2
74.2
27.7
12.3
16.4
0.48

45.5–76.7
34.6–45.1
67.8–89.8
23.9–30.6
12.7–19.9
7.0–10.5
0.30–0.40

65.0–67.7
38.6–39.0
76.4–87.7
16.0–29.5
14.4–23.8
9.8–13.8
0.28

Data from Møller (2003)
Both sides

Anderson, 1994). Nasal pores 2, one set anteroventrally to nostril, another posterodorsally. Suborbital pores 6. Preoperculomandibular pores 8, 4
arising from dentary (4 mandibular pores) and 1

from anguloarticular and 3 from preopercle (4preopercular pores). Interorbital and occipitalpores absent. Free neuromasts scattered on dorsal
and lateral side of head, nape, and above upper

New Deep-sea Eelpout from Japanlip.
Lateral line con¿guration with 3 rows of bodyneuromasts and short predorsal branch on nape(Fig. 4). Predorsal branch very short, with 7 neuromasts (5 in right side). Dorsolateral branchwith 27 neuromasts (23), originating above gill
opening and continuing to posterior half of caudal region. Mediolateral branch with 62 neuromasts (67), originating at posterior quarter oftrunk and continuing to caudal ¿n base. Ventral
branch with 55 (49).
Body covered with small cycloid scales. Predorsal area, abdomen and pectoral ¿n basenaked. Vertical ¿ns naked anteriorly, 1/3 to 1/2
scaled posteriorly. Caudal ¿n scaled.
Osteology. Suborbital bones 6: ¿rst bone largest, articulating with palatine; others small, tubelike. Maxilla long, slender. Premaxilla with
developed ascending process. Dentary withprominent knob anteroventally. No submental
crests. Palatopterygoid series (＝palatine, mesopterygoid and ectopterygoid) well developed (Fig.
5). Quadrate with developed notch posteriorly
for symplectic. Opercle with a single projection
on anterodorsal margin. Parasphenoid wing
reduced, articulating with pterosphenoid andfrontal dorsally. Ceratohyal-epihyal articulationsmooth. Branchiostegal rays 4 on ceratohyal, 1
on ceratohyal-epihyal junction, and 2 on epihyal.
Lower pharyngeal teeth well developed. Three
pharyngeals with tooth patch. Pectoral actinosts
4. Scapular foramen enclosed by bone. Postcleithrun single, slender. No pelvis. Epurals 1,
upper hypural plate fused to preural centra 1.
Lower hypural plate fused to parhypural.
Epineuals from vertebra 1 and pleural ribs fromvertebra 4 (3 in left) and continuing posteriorly(positions of the last epineural and the last pleural rib were impossible to be determined fromradiographs). Vertebral centra symmetrical. Anal¿n pterygiophore 5 inserted anterior to haemal
spine of ¿rst caudal vertebra. Caudal ¿n with 2
epural, 5 upper and 5 lower hypural rays.
Color. Fresh condition just after capture isshown in Fig. 1; following description based onrecently formalin ¿xed and alcohol preserved

55

specimen. Head and body dark brown. Nasal
tube white. Pectoral ¿n dark purple. Two whitish
horseshoe-shaped blotches on middle of dorsal¿n (Figs. 1, 4). Roof of oral cavity with melanophores. Peritoneum black.
Etymology. The speci¿c name is adopted inhonor of Peter Rask Møller, University of
Copenhagen, in recognition of his valuable contributions to systematics on deep-sea eelpouts
including Pachycara.
Distribution. Known only from the Western
North Paci¿c off Kii Peninsula, Honshu, Japan at
4,093 m depth.
Comparison. Pachycara moelleri sp. nov.
appears to be distinct from all species in having 7
branchiostegal rays (4–5 in Pachycara rimae
Anderson, 1989 and 6 in the other species),
although the original description of Pachycara
cousinsi Møller and King, 2007 lacks the branchiostegal ray count.
In having 4 rows of neuromasts in lateral lines,
P. moelleri sp. nov. is the most similar to
Pachycara schcherbachevi Anderson, 1989 andPachycara andersoni Møller, 2003, both species
known from the Indian Ocean. The new species
is distinguished from them in having a shorter
mediolateral branch of the lateral line system, no
pseudobranch ¿laments, no pelvic ¿ns, slightly
larger interorbital width and double tooth rows
with higher numbers of teeth on the palatinesand dentary which are dependent on the different tooth-row numbers (Table 1). Pachycaramoelleri sp. nov. is further distinguished fromP. schcherbachevi in having a larger head length(14.7% SL vs. 11.4–12.0% SL) and higher pectoral ¿n ray counts (19 vs. 16). The new species issimilar to P. andersoni in having a robust body,
but it is further separated from the latter species
in having tricupsid and bicupsid gill rakers (Fig.
2).
Five species were described from the Indian
Ocean including the above two (Anderson, 1989;
Møller, 2003; Møller and King, 2007). The
remaining species, i.e., Pachycara arabica Møller, 2003, P. cousinsi and Pachycara priedei
Møller and King, 2007, are somewhat similar to56

G. ShinoharaFig. 4.

Lateral line system of Pachycara moelleri sp. nov., holotype, NSMT-P 105631, female, 312.0 mm SL.

Fig. 5. Computed tomography for head of Pachycara moelleri sp. nov., holotype, NSMT-P 105631, female. BNS,
branched neural spine. Inset showing frontal view of head and captured part (lighter area).

P. moelleri sp. nov. in having no pelvic ¿ns, 0–3
pseudobranch ¿laments and a pectoral ¿n base/length ratio of 0.33–0.50. In addition to the different number of neuromast rows (＝branches) in
the lateral lines (3 in P. arabica and 2 in P. cousinsi
and P. priedei), P. moelleri sp. nov. is further distinguished from P. arabica in having a shorter
pectoral ¿n length (10.9% SL vs. 13.3% SL in
the latter species), from P. cousinsi in its shorter
predorsal length (22.4% SL vs. 26.5% SL), andfrom P. priedei in its different body coloration(dark brown vs. pale pink).
Among nine species recorded from the Paci¿c
Ocean (Anderson, 2006, 2009; Anderson andFedorov, 2004), P. moelleri sp. nov. resembles
Pachycara bulbiceps (Garman, 1899), some indiviuals of Pachycara mesoporum Anderson, 1989,
and Pachycara nazca Anderson and Bluhm,
1997 in lacking pelvic ¿ns. The new species canbe separated from P. bulbiceps by the presence ofpredorsal and dorsolateral lateral line branches
and from P. nazca in having predorsal, dorsolat-

New Deep-sea Eelpout from Japaneral, and ventral branches. It can be distinguishedfrom P. mesoporum by its lack of a single, medial
occipital pore (vs. presence) and presence of 2
postorbital pores (vs. 3–4).
Two species are known from the Southern
Ocean (Anderson, 1990, 1991) and eight (including above P. bulbiceps) from the Atlantic (Anderson, 1989; Biscoito and Almeida, 2004; Anderson and Mincarone, 2006). The new species
differs from all Antarctic and Atlantic species,
except P. bulbiceps, in lacking pelvic ¿ns andpseudobranch ¿laments.
Taxonomic notes. A branched neural spine(Fig. 5: BNS) has not been reported among the
Zoarcidae. It is considered abnormal and was notincluded to the diagnosic characters.
Acknowledgments
I express my sincere thanks to the following
persons: Ken Fujimoto (National Research Institute of Fisheries Science, Yokohama), Masanori
Okanishi (University of Tokyo), and all of¿cers
and crew of the R/V Soyo-maru for supplying thespecimen. Thanks to Toshihiko Fujita and Kaoru
Kuriiwa (NSMT) for pictures of holotype andYutaro Inoue (NSMT) for drawing of holotype.
M. Eric Anderson (South African Institute of
Aquatic Biodiversity) read an early draft manuscript critically and helped with English language
adjustments.
Literature Cited
Anderson, M. E. 1982. Revision of the ¿sh genera Gymnelus
Reinhardt and Gymnelopsis Soldatov (Zoarcidae),with two new species and comparative osteology ofGymnelus viridis. National Museum of Canada Publications in Zoology, (17): i–iv＋1–76.
Anderson, M. E. 1989. Review of the eelpout genus
Pachycara Zugmayer, 1911 (Teleostei: Zoarcidae),with description of six new species. Proceedings of the
California Academy of Sciences, 46: 221–242.
Anderson, M. E. 1990. Zoarcidae eelpouts. Pages 256–276 in Gon, O. and P. C. Heemstra, eds. Fishes of theSouthern Ocean. J. L. B. Smith Institute of Ichthyology, Grahamstown.
Anderson, M. E. 1991. Studies on the Zoarcidae (Tele-57

ostei: Perciformes) of the Southern Hemisphere. V.
Two new spcies from the Weddell Sea, Antarctica.
Cybium, 15: 151–158.
Anderson, M. E. 1994. Systematics and osteology of the
Zoarcidae (Teleostei: Perciformes). Ichthyological
Bulletin of the J. L. B. Smith Institute of Ichthyology,(60): 1–120.
Anderson, M. E. 2006. Studies on the Zoarcidae (Teleostei: Perciformes) of the Southern Hemisphere. XII.
Two new lycodine species. Species Diversity, 11: 183–
190.
Anderson, M. E. 2009. Zoarcidae eelpouts. Pages 287–
289 in Nakaya, K., M. Yabe, H. Imamura, M. Romero
Camarena, and M. Yoshida, eds. Deep-sea ¿shes ofPeru. Japan Deep Sea Trawlers Association, Tokyo.
Anderson, M. E. and H. Bluhm. 1996. Description of a
new species of Pachycara Zugmayer, 1911 from theabyssal South-eastern Paci¿c and redescription of P.
thermophilum Geistdoerfer, 1994, with a new keys tothe species. Transactions of the Royal Society of South
Africa, 51: 219–227.
Anderson, M. E. and V. V. Fedorov. 2004. Family Zoarcidae Swainson 1839 eelpouts. California Academy of
Sciences Annotated Checklists of Fishes, (34): 1–58.
Anderson, M. E. and M. M. Mincarone. 2006. Studies on
the Zoarcidae (Teleostei: Perciformes) of the southernhemisphere. IX. A new species of Pachycara from thesouthwestern Atlantic. Zootaxa, 1177: 21–26.
Biscoito, M. and A. J. Almeida. 2004. New species ofPachycara Zugmayer (Pisces: Zoarcidae) from the
Rainbow hydrothermal vent ¿eld (Mid-Atlantic Ridge).
Copeia, 2004: 562–568.
Garman, S. 1899. Reports of an exploration off the west
coasts of Mexico, Central and South America, and off
the Galapagos Islands, in charge of Alexander Agassiz,by the U. S. Fish Commission steamer “Albatross” during 1891. XXVI. The ¿shes. Memoirs of the Museum of
Comparative Zoology, 24: 1–431.
Geistdoerfer, P. 1994. Pachycara thermophilum, une nouvelle espèce de poisson Zoarcidae des sites hydrothermaux de la dorsale médio-atlantique. Cybium, 18: 109–
115.
Gill, T. N. 1884. On the anacanthine ¿shes. Proceedingsof the Academy of Natural Sciences of Philadelphia,
36: 167–183.
Peden, A. E. and M. E. Anderson. 1978. A systematic
review of the ¿sh genus Lycodapus (Zoarcidae) withdescriptions of two new species. Canadian Journal of
Zoology, 56: 1925–1961.
Møller, P. R. 2003. Two new species of Pachycara Zugmayer (Teleostei: Zoarcidae) from the Indian Ocean,with redescription of Pachycara shcherbachevi Anderson. Copeia, 2003: 357–365.
Møller, P. R. and M. E. Anderson. 2000. Assignment of

58

G. Shinohara

Lycodes microcephalum Jensen, 1902 to Pachycara
Zugmayer, 1911 (Teleostei: Zoarcidae). Cybium, 24:
61–65.
Møller, P. R. and N. King. 2007. Two new species ofPachycara (Teleostei: Zoarcidae) from the Sub-Antarctic southern Indian Ocean, and range extension of
Lycenchelys antarctica. Copeia, 2007: 586–593.
Nakaya, K., M. Yabe, H. Imamura, M. Romero Camarena,and M. Yoshida, eds. 2009. Deep-sea ¿shes of Peru.
Japan Deep Sea Trawlers Association, Tokyo. 356 pp.
Reinhardt, J. C. H. 1831. Bidrag til vor Kundskab om
Grönlands Fiske. Oversigt over det Kongelige Danske
Videnskabernes Selskabs Forhandlinger og dets Medle-

mmers Arbeider (Kjøbenhavn), 1830–1831: 18–24.
Saruwatari, T., J. A. López and T. W. Pietsch. 1997. Cyanine Blue: A versatile and harmless stain for specimen
observation. Copeia, 1997: 840–841.
Zugmayer, E. 1911. Diagnoses de poissons nouveaux
provenant des campagnes du yacht “Princesse-Alice”(1901 à 1910). Bulletin de lʼInstitut Oceanographique(Monaco), (193): 1–14.
Manuscript received 10 November 2011; revised 26 February 2012; accepted 5 March 2012.
Associate editor: S. Kimura