Lycenchelys aratrirostris Andriashev and Permitin 1968

Lycenchelys aratrirostris Andriashev and Permitin, 1968

Lycenchelys aratrirostris Andriashev and Permitin, 1968: 615, figs. 24 (type locality: off South Shetland Islands); Anderson, 1988: 89, figs. 30-31; Anderson, 1990b: 259, fig. 3.

Material examined. South Shetland Islands: SAM 34599 (1 specimen, 202 mm SL), off Elephant Island, 61°12.6'S, 54°32.3'W, 559 m, POLARSTERN sta. AGT 15, Agassiz trawl, 19 Nov. 1996, K.-H. Kock. SAM 34534 (5, 176-220 mm SL), off King George Island, 62°18.9'S, 58°41.7'W, 491-497 m, POLARSTERN sta. AGT 175, Agassiz trawl, 24 Dec. 1996, K.-H. Kock. SAIAB (RUSI) 53455 (4; 199-264 mm SL), off Smith Island, 700 m, POLAR DUKE, otter trawl, 5 July 1996, A. DeVries.

Diagnosis. Lycenchelys aratrirostris is distinguished from its congeners by the following combination of characters: fleshy mandibular symphysis deep, its length 18-20 % HL; suborbital pores 6-7; vertebrae 22-24 + 77-86 = 100-110.

Description. Vertebrae 22-24 + 77-81 = 100-104; D 951-00; A 80-82; P 14-16; C 10-12; pelvics 3; branchiostegal rays 6; gill rakers 2 + 9-10; vomerine teeth 0-11; palatine teeth 0-11; pseudobranch filaments 0-7; pyloric caeca 2. Following proportions as percent SL (specimens 176-220 mm SL first followed by 264 mm SL male in parentheses): head length 16.4-17.2 (20.7); head width 7.5-8.2 (11.1); head depth 7.3-7.8 (9.8); predorsal length 18.2-20.0 (24.0); preanal length 34.5-36.7 (41.6); pectoral base depth 4.7-7.0 (4.2); pectoral-fin length 5.6-8.7 (10.5); body depth 7.8-8.6 (9.3); gill slit length 4.9-5.9 (4.6). Following proportions as percent HL, data presented as above: head width 44.2-47.8 (52.7); head depth 42.6-47.8 (47.3); mandibular symphysis length 15.4-20.7 (19.8); upper jaw length 39.5-43.2 (46.4); snout length 21.0-25.4 (26.8); eye diameter 18.1-25.6 (17.2); gill slit length 28.3-34.5 (22.1); pectoral-fin length 47.3-50.7 (50.7); interorbital width 6.7-8.4 (6.9); interpupillary width 26.4-27.8 (21.4); caudal-fin length 14.6-19.4 (12.7); pelvic-fin length 7.6-12.0 (6.7). Pectoral base/length ratio 39.2-46.8 (40.1).

Variation in cephalic pore patterns minimal. Preoperculomandibular pores 8 in all; suborbital pores 6 + 0 except in two specimens with pores 6 + 1; postorbital pores 1 and 4 present in all, pore 1 doubled on right side of one fish, another with postorbital pore 3 present on left side; nasal pores 2 in all; no occipital or interorbital pores. Caudal fin with two epural rays and 4-5 upper and 4-5 lower hypural rays. Dorsal-fin origin associated with vertebrae 3-4, with no free pterygiophores; 2-4 anal-fin pterygiophores inserted anterior to haemal spine of first caudal vertebrae. Two lateral lines: ventrolateral branch commences behind postorbital pore 4, courses steeply down to abdomen and continues to tail tip; mediolateral branch commences about half pectoral-fin length behind pectoral margin and continues to tail tip, neuromasts widely and irregularly spaced. Scales extend completely across body to vertical through anus or just behind it except in 264 mm SL male where they are present to a vertical through pectoral base (absent on nape), on pectoral base and fin to about a third its length, abdomen and dorsal and anal fins to about half their height anteriorly, to about 80% their height near tail tip. Vomerine teeth 1-3 in specimens 176-202 mm SL, absent in 220 mm fish, 11 in 264 mm male. Palatine teeth 1-3 in 180-220 mm specimens, absent in 176 mm fish, 911 in 264 mm male.

Remarks. This species was described from a single specimen taken off the South Shetland Islands, and I added data from three more from that area and the Weddell Sea (Anderson, 1988). The new material considerably increases knowledge of the species in characters, size (to 264 mm SL) and depth range (491-1120 m). Two gravid females are among the present sample, both in SAM 34534; one, at 180 mm SL had 35 ova 2.34.1 mm in diameter, the other, at 194 mm SL had ripening ova 0.9-2.0 mm in diameter. The smallest male, at 176 mm SL, had mature testes. The largest male, at 264 mm (RUSI 53455), exhibits secondary male characteristics found in a few Lycenchelys species (see above), such as a longer, deeper and wider head, longer upper jaw and pectoral fin, deeper body and smaller eye, caudal fin and gill slit compared to females or smaller males.