Paraliparis parviradialis, Stein, 2012

Stein, David L., 2012, Snailfishes (Family Liparidae) of the Ross Sea, Antarctica, and Closely Adjacent Waters 3285, Zootaxa 3285, pp. 1-120 : 90-91

Paraliparis parviradialis n. sp.

Figs. 63, 64

Holotype. NMNZ P.043720, ripe? female, 282 mm TL, 261 mm SL, 71°52.37' S, 174°04.29' E, NW edge of Mawson Bank, R / V Tangaroa, Stn. IPY / CAML TAN 0802 /167, 25 February 2008, 1954– 1990 m. NMNZ P.043720/1, cleared and stained right pectoral girdle.

Diagnosis. V 68, D probably 60, A 54, C 7. Teeth uniserial. Pectoral fin rays 21–22, notch moderately deep, notch rays rudimentary or normal but shortened, about 1/3 upper lobe length. Pectoral girdle with three (2+0+1) small oval radials; R2 largest; radials without notches, fenestrae absent. Scapula with broad blade, short broad helve. Coracoid with broad blade with dorsal slit and two fenestrae, large hemispherical basal notch, and long, slender helve. Abdomen length greater than twice head length.

Description. Counts. V 68 (13+55), D 60 (possibly 61, see below), A 54, C 7, P 21–22 (14+4+4, 15+2+4), radials 3 (2+0+1), pc 8, pore formula unknown. Ratios. HL 16.5, HW na, sn 5.0, E 4.5, orbit 4.7, io 6.2, uj 7.0, go 2.4, preD 26.1, preA 46.9, sna 17.6, ma 15.6, aAf 32.7, UPL 10.2, LPL 13.3, pabd 35.8. In % HL: HW na, sn 30.4, E 27.4, orbit 28.5, io 37.6, uj 42.2, go 14.8, preD 158.2, preA 284.0, sna 106.7, ma 94.4, aAf 198.4, UPL 61.9, LPL 80.3, pabd 216.9, cp 3.0.

Head small, dorsal profile rounded evenly from snout to occiput. Snout short, blunt. Nostrils on a horizontal through mid-orbit. Mouth horizontal, subterminal, oral cleft short, not quite reaching anterior margin of orbit. Lower jaw deep, heavy. Teeth simple, stout, sharp canines, decreasing in size anteriorly; uniserial in both jaws except near symphysis of premaxilla, where irregularly bi- or tri-serial. About 25 teeth in a row on one side of premaxilla. Premaxillary teeth about 50 on each side. Symphyseal gaps wide in both jaws. Eye prominent, pupil very large, about 2/3 or more of eye diameter. Gill opening completely above pectoral fin base, 1/6–1/7 HL, its ventral end distinctly above level of dorsal pectoral fin ray; opercular flap small, supported by crescent-shaped opercle. Pore formula unknown, damaged, small, pale in contrast with dark skin. Chin pores smaller than remaining pores, paired, not in a pit and lacking any skin fold, the distance separating them about equal to diameter of one pore.

Pectoral fin short, longest ray of upper lobe not reaching to middle of abdomen. Uppermost ray probably on horizontal with lower part of orbit. Upper lobe rounded, of 14–15 rays, notch rays 2–4 in a deep notch, some, but not all, rudimentary; lower lobe of four rays, insertion of lowest ray about midway between orbit and opercle tip, its longest ray reaching to below tip end of upper lobe. Pectoral girdle with 3 (2+0+1) small more or less horizontally oval unnotched radials, R2 largest, R1 and R3 of similar size. Scapula base broad, helve smaller, broad and well developed. Coracoid head with a dorsal slit, two fenestrae, and broad deep basal notch at base of long slender helve.

Body thick, deepest behind head. Dorsal fin insertion between vertebrae 6–7, anal fin insertion between vertebrae 13–14. Penultimate vertebra three supports two dorsal rays (an anomaly) only one included in ray count of 60; if extra ray is normal, dorsal fin ray count would be 61. Dorsal and anal fins deepest at about 2/3 of SL posterior. Anus below tip of opercle, well behind symphysis of lower pectoral fin lobes, below bases of ventral upper lobe rays. Peritoneum visible through body wall. Hypural complex fused, slit absent. Caudal fin of 7 (3/4) rays, auxiliary rays absent. Pyloric caeca eight, of different lengths, long and digitate, not matted or flattened. SECM well developed. Skin thick, fibrous.

Color of body in alcohol rosy purple, head, dorsal, and anal fins darker, remaining skin on snout and head blackish, distal part of upper pectoral fin lobes, and lower lobe rays brown, anal region blackish. Orobranchial cavity blackish, peritoneum black, stomach and pyloric caeca pale.

The specimen has eggs of about 3 mm.

Distribution. Known only from the holotype, collected from the northwest edge of Mawson Bank in 1954– 1990 m.

Etymology. The name parviradialis from the Latin parvus, small, and radial, denoting the small size of the pectoral radials.

Comparisons. The new species is externally most similar to Paraliparis neelovi and can easily be confused with it. Positive identification requires examination of pectoral girdle structure to see the small oval radials (vs large, round radials) and notched coracoid (vs no slits or notch, shorter helve). External differences include more caudal fin rays (7 vs 6), narrower interorbital space (38 vs 46–52% HL), pectoral fin notch depth (moderate vs deep), greater anus to anal fin distance (about 33 vs 25–29% SL), and its location below the base of the pectoral fin notch (vs below the middle of lower lobe rays), longer abdomen (about 217 vs 167% SL), and darker head and body color. Its general appearance and uniserial teeth also make it similar to P. copei , from which it differs in having 3 (vs 4) radials, a longer gill opening (vs pore-like) presence of a gill flap (vs absent) and other counts and ratios. It is also similar to P. mentikoilon , but differs in not having the chin pores in a pit (vs in a pit with anterior fold), fewer vertebrae (68 vs 71), shorter upper pectoral fin lobe (62 vs 70% HL), longer lower lobe (80 vs 68% HL), smaller radials (vs normally large), notch rays more closely spaced and better developed (vs widely separated and reduced to bases), and a coracoid with a longer helve and large basal notch (vs shorter, stout, and absent).