Lycenchelys argentina Marschoff, Torno and Tomo, 1977

M. Eric Anderson, 2006, Studies on the Zoarcidae of the southern hemisphere. X. New records from western Antarctica., Zootaxa 1110, pp. 1-15: 7-8

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Lycenchelys argentina Marschoff, Torno and Tomo, 1977


Lycenchelys argentina Marschoff, Torno and Tomo, 1977 

(Fig. 1)

Lycenchelys argentinus Marschoff, Torno and Tomo, 1977  ZBK  : 3, text fig. ( type locality: off South Orkney Islands   .

Lycenchelys argentina  : Anderson, 1988: 92; Anderson, 1990b: 260, fig. 4.

Material examined. USNM 356657 (2 specimens; 90-106 mm SL), W. of South Orkney Isls. , 60°45.5'S, 48°13.5'W, 2511-2542 m, ISLAS ORCADAS coll. UMO 116, 10 ft beam trawl, 18 Feb. 1976, H. H. DeWitt.GoogleMaps 

Diagnosis. Lycenchelys argentina  is distinguished from its congeners by the following combination of characters: Vertebrae ca. 90 (holotype) to 95; dorsal-fin origin associated with vertebrae 8-9; caudal-fin length 25.7-30.2% SL; suborbital pores 6 + 0; gill rakers 3 + 12-15 = 15-18; P 17-18; minute papillae covering dorsal region of head and lips in adults.

Description. Vertebrae 20-21 + 71-74 = 91-95; D 84-87; A 74-77; P 17-18; C 9-10; pelvics 3; branchiostegal rays 6; gill rakers 3 + 12; vomerine teeth 3-4; palatine teeth 5-8; pseudobranch filaments 3-4; pyloric caeca 2. Following proportions as percent SL: head length 17.6-17.8; head width 8.1-8.7; head depth 8.0-8.5; predorsal length 22.9-23.4; preanal length 33.6-36.1; pectoral-base depth 3.9-4.3; pectoral-fin length 11.4-11.7; body depth 6.0-6.5; gill slit length 6.4-7.1. Following proportions as percent HL: head width 45.5-49.5; head depth 44.9-48.1; upper jaw length 41.2-42.4; snout length 21.4-23.7; eye diameter 20.6-23.0; gill slit length 36.1-39.9; pectoral-fin length 63.9-66.0; interorbital width 10.2-10.3; interpupillary width 23.1-24.1; caudal-fin length 25.7-28.0; pelvic-fin length 15.6-18.2; pectoral base/length ratio: 34.2-37.3.

Variation in cephalic pore patterns between these two juveniles and the 248 mm SL adult holotype are noteworthy. All three specimens with suborbital pores 6 + 0 and eight preoperculomandibular pores. However, the holotype has a median occipital and an interorbital pore, both absent in the juveniles. The postorbital canal of the holotype has four pores on the right and three on the left, whereas one juvenile has two pores on both sides, the other has three on the right and two on the left. Caudal fin relatively long. Caudal skeleton with one epural, four upper hypural and 45 lower hypural rays. Dorsal-fin origin retrograde, associated with vertebrae 8-9 in juveniles, but snout short, thus predorsal length not diagnostic. No free dorsal-fin pterygiophores. Anal-fin origin associated with ultimate precaudal vertebrae, with four pterygiophores inserted anterior to haemal spine of first caudal vertebra. Last dorsal-fin ray associated with third preural centrum, last anal ray associated with second preural centrum. Holotype with ventrolateral and mediolateral branches of lateral line, juveniles with very indistinct lateral line neuromasts of both branches. Scales in smaller specimen on tail and anteriorly on dorsum to about half an eye diameter behind dorsal-fin origin, absent on fins and abdomen in larger specimen. Gill slit extending ventrally to opposite lowermost pectoral-fin ray or slightly lower. Minute papillae described in adult holotype not developed in these juveniles, but flat, round clumps of thickened tissue present on snout and interorbital region are interpreted as precursors to adult, wart-like papillae.

Remarks. The original description of this species is very brief and I redescribed it on the basis of observations made for me on the holotype by A. E. Gosztonyi (Anderson, 1988). The variation in the cephalic pore patterns seen in the holotype and the two new specimens is not uncommon in species of Lycenchelys  ZBK  (or some other zoarcids like Gymnelus  ZBK  or Pachycara  ZBK  ; Anderson, 1982, 1989). Five species of Lycenchelys  ZBK  are known to have the interorbital pore present or absent, and three others have varying numbers of occipital pores, with L. scaurus  having them present or absent (Anderson, 1995). Pachycara crossacanthum  ZBK  also has the occipital commissure and pores present or absent (Anderson, 1989).