Pachycara alepidotum Anderson & Mincarone, 2006, new species
Creators: name: M. Eric Anderson
name: Michael Maia Mincarone
Publisher: name: Zenodo
Year: 2006
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Perciformes
Zoarcidae
Pachycara
Pachycara alepidotum

description: Pachycara alepidotum, new species
(Fig. 2)
Holotype: MOVI 21033 (male, 255 mm SL); off Rio Grande do Sul state, Brazil; 34°31.4'S, 51°45.8'W; KINPO MARU 58, sta. 85; bottom trap; 807 m; C. M. Lima-Silva; 11 Feb. 2002.
Paratypes: SAIAB (RUSI) 75089 (male; 199 mm SL); same data as holotype. MOVI 21034 (male, 209 mm SL) and MOVI 21035 (female, 282 mm SL); off Rio Grande do Sul, Brazil; 34°19.7'S, 51°45.8'W; KINPO MARU 58, sta. 131; bottom trap; 788 m; C. M. Lima-Silva; 3 Mar. 2002.
Additional material: MNRJ 27754 (sex unknown, 250 mm SL); off Espírito Santo, Brazil; 19°42.7'S, 38°36.5'W; THALASSA, sta. D - 0504; GOV demersal trawl; 902-910 m; P. A. S. Costa; 29 Jun. 1999. Not seen.
Diagnosis. A species of Pachycara as defined by Anderson (1989, 1994) with the following combination of characters: scales and ventral lateral line absent; caudal vertebrae 67-69; gill rakers on upper limb 1-2.
Description. Counts and measurements, holotype first followed in parentheses by range of variation in paratypes: vertebrae 25 + 67 = 92 (25-26 + 67-69 = 92-95); D 87 (87-90); A 67 (67-70); C 9 (8-9); P 18 (18); pelv. 2 (2); vomerine teeth 2 (2-3); palatine teeth 4 + 4 (4-6 + 3-5); gill rakers 1 + 14 (1-2 + 12-16 = 13-18); branchiostegal rays 6 (6); pseudobranch filaments 4 (4). Following measurements in percent SL: head length 17.8 (16.3-17.8); head width 10.9 (9.6-11.1); head depth 11.1 (8.8-10.7); pectoral fin length 10.9 (9.4-12.5); predorsal length 20.0 (18.5-23.9); preanal length 45.3 (44.8- 47.5); body depth 12.1 (10.6-12.3); gill slit length 6.5 (5.4-6.1); caudal fin length 7.1 (4.6-7.0). Following measurements in percent HL: head width 61.6 (55.1-67.5); head depth 62.3 (53.7-63.9); upper jaw length 56.1 (36.0-51.8); pectoral fin length 61.6 (57.4- 76.5); snout length 22.7 (20.8-24.4); eye diameter 17.9 (16.2-19.9); gill slit length 36.4 (33.2-36.6); interorbital width 9.3 (8.9-12.4); interpupillary width 29.1 (29.3-35.9); pelvic fin length 13.3 (10.8-17.6). Pectoral base/length ratio: 39.4 (36.7-50.2).
Head ovoid in young, more dorsoventrally depressed in adult male holotype. Scales and epidermal prickles absent. Spectacle of eye circular or slightly ovoid. Gill slit extending ventrally to opposite fourth or fifth ventralmost pectoral ray. Lobe at dorsal margin of gill slit weak, not extending anteriorly one-quarter eye diameter. Pectoral fin origin below body midlne, insertion on abdomen; posterior margin of fin wedge-shaped; middle pectoral rays longest; ventralmost four thickened, tips very slightly exserted.
Mouth subterminal, slightly oblique, upper jaw extending to middle of eye or its posterior margin (holotype). Rear lobe of lower lip well developed in holotype. Oral valve very weakly developed, well separated from anterior margin of vomer. Jaw teeth small, conical; dentary with three irregular rows anteriorly, blending into single posterior row; premaxilla with two anterior rows, blending into single posterior row. Vomerine and palatine teeth relatively few; palatine teeth in short anterior patch.
Cephalic lateralis system in primitive state for Pachycara (Anderson 1989), with two postorbital pores (numbers one and four), two pairs of anterior supraorbitals (nasals), six suborbitals, eight preoperculomandibulars and no occipitals or interorbital. Body lateral line with complete mediolateral branch originating directly behind last postorbital pore (Fig. 3). Predorsal branch with 17-20 neuromasts running from above or just behind eye to dorsal fin origin. No ventral or dorsolateral branches, few neuromasts in these regions on body and tail.
Dorsal fin origin associated with fourth vertebra, with no free pterygiophores anteriorly. Anal fin origin associated with ultimate precaudal or first caudal vertebrae, with two pterygiophores inserted anterior to haemal spine of first caudal vertebra. Last dorsal ray associated with fourth preural vertebra, last anal ray associated with second preural vertebra. Caudal fin with one epural, four upper and four lower hypural rays. Gill rakers short, triangular, dorsalmost three in holotype shallowly furcate; single gill raker on epibranchial in three specimens, two in MOVI 21035, directed anteroventrally. Pseudobranch filaments long, simple.
Color uniformly dark chocolate brown, unpaired fins black. Eye blue. Abdomen with bluish tinge.
Distribution. Southern Brazil, from Espírito Santo to Rio Grande do Sul, in 788-910 m.
Etymology. From the Greek lepidotos, covered with scales, and the negative prefix referring to the species scaleless condition.
Comparisons. Pachycara alepidotum is the second of 21 known species of the genus without scales, the other being P. shcherbachevi (Anderson 1989; Møller 2003), suggesting possible relationship. However, the two differ in several trenchant features including the more numerous vertebrae in P. shcherbachevi (120-122 vs 92-94 in P. alepidotum), pelvic fin rays 3 in P. shcherbachevi vs 2 in P. alepidotum, smaller head (length 11.4-12.0 in P. shcherbachevi vs 16.3-17.8), more posterior dorsal fin origin (origin associated with vertebrae 7-8 in P. shcherbachevi vs 4), presence of the ventral branch of the lateral line system in P. shcherbachevi vs its absence, and presence of an interorbital pore in P. shcherbachevi vs its absence. In addition, the habitats of P. shcherbachevi and P. alepidotum are different, the former is an Indian Ocean abyssal species, taken at 2600-3190 m, while the latter is an upper bathyal (788-807 m) Atlantic species. On the basis of its low vertebral counts, two pelvic fin rays and lack of ventral lateral line, P. rimae Anderson, an eastern Pacific abyssal species, seems close to P. alepidotum, but it differs in the presence of scales, its fewer branchiostegal rays (4-5 in P. rimae vs 6), more posterior dorsal fin origin(associated with vertebra 8 in P. rimae vs. 4), fewer pectoral fin rays (15 in P. rimae vs 18) and lack of a pseudobranch. Other bathyal southeastern Pacific (i.e., P. mesoporum Anderson and P. pammelas Anderson) or eastern Atlantic (P. crassiceps Roule, P. crossacanthum Anderson) species do not seem close to P. alepidotum on the basis of their complete squamation, higher vertebral counts and more complex lateral line systems. Thus the relationships of P. alepidotum are presently unclear.
Remarks. The single trawl-caught specimen (MNRJ 27754) was taken in a Great Opening Vertical (GOV) net, mouth size measuring 36 x 47 m. The bottom temperature at 900 m was 3.4°C. The trap-caught specimens were collected from galvanized circular crab pots baited with fish. The benthic fauna was diverse in deep-sea corals, echinoderms, mollusks and crustaceans. Fishes observed at and near the trap locations were hag fish (Eptatretus menezesi Mincarone), sharpnose sevengill shark (Heptranchias perlo (Bonnaterre), freckled catshark (Scyliorhinus haeckelii (Miranda Ribeiro), dogfish (Squalus sp.), an undescribed Conger, dragonfish (Idiacanthus atlanticus Brauer), Marini’s grenadier (Caelorinchus marinii Hubbs), Atlantic grenadier (Nezumia aequalis (Günther), common fangtooth (Anoplogaster cornuta (Valenciennes), banded yellowfish (Centriscops humerosus (Richardson), sculpin (Cottunculus granulosus Karrer), tilefish (Lopholatilus villarii Miranda Ribeiro), and corocoro grunt (Orthopristis ruber (Cuvier).
description: Published as part of M. Eric Anderson & Michael Maia Mincarone, 2006, Studies on the Zoarcidae (Teleostei: Perciformes) of the southern hemisphere. IX. A new species of Pachycara from the southwestern Atlantic., pp. 21-26 in Zootaxa 1177 on pages 23-25