Studies on the Zoarcidae of the southern hemisphere. X. New records from western Antarctica.
Author
M. Eric Anderson
text
Zootaxa
2006
1110
1
15
http://www.zoobank.org/urn:lsid:zoobank.org:pub:F40B31EF-77F0-42C8-B373-FCD07872A31A
journal article
z01110p001
F40B31EF-77F0-42C8-B373-FCD07872A31A
Dieidolycus leptodermatus
Anderson, 1988
Dieidolycus leptodermatus
Anderson, 1988: 72
, fig. 15 (type locality:
eastern Scotia Sea
);
Anderson, 1990b: 257
, fig. 1.
Material examined.
Scotia Sea:
USNM
356650
(3 specimens; 115-150 mm SL) and
RUSI
60087
(2; 88-171 mm SL):
off Candelmas Isl.
,
57°00.4'S
,
26°10.1'W
, ISLAS ORCADAS coll. UMO 38,
10 ft beam trawl
, 2744-2745 m,
22 May 1975
,
H. H. DeWitt
.
USNM
356655
(1; 134 mm SL):
W of South Orkney Islands
,
60°45.5'S
,
48°13.5'W
, ISLAS ORCADAS coll. UMO 116,
10 ft beam trawl
, 2511-2542 m,
18 Feb. 1976
,
H. H. DeWitt
.
Diagnosis.
Dieidolycus leptodermatus
is distinguished from its two congeners by the following combination of characters: suborbital pores 6, occipital and interorbital pores absent, pectoral-fin rays 16-17; dorsal fin origin associated with vertebrae 2-3 (not 23' as mistakenly given in
Anderson, 1990b
).
Description. Vertebrae 22-23 + 55-58 = 78-81; D 73-77; A 55-59; P 16-17; C (6) 8-10; pelvics 2; branchiostegal rays 6; gill rakers 2-3 + 9-11 = 12-13; vomerine teeth 6-15; palatine teeth 6-17; pseudobranch absent. Following proportions as percent SL: head length 21.3-24.7; head width 9.5-11.3; head depth 11.0-11.6; predorsal length 23.2-24.6; preanal length 46.6-48.4; pectoral base depth 4.4-5.2; pectoral-fin length 12.9-14.0; body depth 9.2-10.9; gill slit length 7.5-8.4. Following proportions as percent HL: head width 40.7-52.9; head depth 49.1-52.1; upper jaw length 34.5-38.5; snout length 26.5-33.0; eye diameter 12.4-15.5; gill slit length 33.4-37.4; pectoral-fin length 58.1-62.4; interorbital width 6.6-7.9; interpupillary width 20.3-27.2; caudal-fin length 20.9-25.4; pelvic-fin length 7.2-24.4. Pectoral base/depth ratio: 31.7-40.1.
Head roughly triangular, eye (spectacle) small, head pores prominent, with whitish outline. Flesh gelatinous, but lateral line present (usually absent in gelatinous zoarcids;
Anderson, 1994
). Lateral line originating just above upper end of gill opening and coursing midlaterally to tail tip (lateral line said to be absent in original description owing to faded specimens; Anderson and Pequeno-R, 1998). Pelvic-fin length highly variable, as dermal sheath covering rays extends distally with growth. Smallest specimen (88 mm SL) with pelvic length 24.4% HL, two largest (150-171 mm SL) with pelvic length 7.2-9.2% HL respectively. Caudal fin rays also quite variable, with usually 2 epural and 7-8 hypural rays, but one fish with 0 + 6 rays and one with 1 + 8 rays. Preoperculomandibular pores 8, suborbital pores 5 + 0, supraorbital (nasal) pores 2, postorbital pores 2 (1 and 4 present except one in USNM 356650, 115 mm SL, with left postorbitals 1, 3 and 4 present), interorbital and occipital pores absent.
Remarks. This rare eelpout was originally described from three specimens taken in the Scotia and Ross seas at depths of 2273-3040 m by the U.S. Antarctic Research Program in 1966-1967. The present six specimens include four smaller and one larger than the type series, including the largest known, a 171 mm SL juvenile female. The size of the immature ovary of this specimen indicates the species probably attains more than 300 mm.