Dieidolycus leptodermatus Anderson 1988
- Dataset
- Studies on the Zoarcidae of the southern hemisphere. X. New records from western Antarctica.
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Chordata
- order
- Perciformes
- family
- Zoarcidae
- genus
- Dieidolycus
- species
- Dieidolycus leptodermatus
description
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.
diagnosis
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, 1990 b).
discussion
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.
materials_examined
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.