Paraliparis nullansa, Stein, 2012

Stein, David L., 2012, Snailfishes (Family Liparidae) of the Ross Sea, Antarctica, and Closely Adjacent Waters 3285, Zootaxa 3285, pp. 1-120 : 82-85

Paraliparis nullansa n. sp.

Figs. 58, 59, 60

Holotype. NMNZ P.043718, ripe female, 298 mm TL, 276 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.043718/1, cleared and stained right pectoral girdle.

Diagnosis. V 71, D 60, A 54, C 7, P 21, notch rays rudimentary. Scapula lacking helve; radials 3 (2+0+1), R2 notched, coracoid with basal notch. Teeth small canines, almost entirely uniserial in each jaw; premaxillary teeth about 40, not reaching posteriorly to end of jaw; anteriormost teeth tiny, difficult to see. Gill opening about 15% HL, entirely above pectoral fin; gill flap absent.

Description. Counts. V 71 (15+56), D 60, A 54, C 7, P 21 (15+2+4), radials 3 (2+0+1), pc 6?, pores 2–6–?–1. Ratios. HL 18.8, HW 14.8, sn 6.0, E 3.3, orbit 5.5, io 7.4, uj 6.6, go 2.9, bd 24.2, preD 32.5, preA 45.6, sna 18.0, ma 15.0, aAf 28.6, UPL 13.3, LPL 14.5, LLD 4.7% SL. In % HL: HW 78.6, sn 32.0, E 17.3, orbit 29.3, io 39.1, uj 35.1, go 15.4, bd 128.7, preD 173.0, preA 242.4, sna 95.8, ma 80.0, aAf 152.4, UPL 70.5, LPL 77.1, LLD 25.2, cp 3.3.

Head short, less than 1/5 SL, low, dorsal profile flat and gradually rising from snout to postorbital region. Snout short, bluntly rounded, projecting slightly beyond upper jaw. Nostrils a short tube or thick raised rim, on horizontal through mid-pupil about half eye diameter anterior to orbit. Mouth horizontal, subterminal; lower jaw broadly rounded, included, oral cleft extending to below anterior half of orbit. Teeth simple, sharp, evenly spaced canines, arranged uniserially for almost entire jaw length. Premaxillary teeth in a single row of about 37 extending to symphysis, a few scattered irregular extra teeth inside them near symphysis; teeth becoming gradually smaller anteriorly, posterior teeth stout, sharp, anterior teeth tiny. Posterior tooth row not reaching to end of oral cleft. Mandibular teeth distinctly smaller than premaxillary teeth, more closely spaced and more numerous, about 60 teeth forming a single row with a few scattered teeth near symphysis. Symphyseal gaps wide in both jaws. Eye prominent with large pupil, orbit diameter slightly less than snout, not entering dorsal profile of head but near it, less than 1/3 HL. Gill opening completely above pectoral fin base, barely reaching to upper pectoral fin ray, about 15% HL.

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FIGURE

Opercular flap absent, opercle narrow, its tip reaching to bottom of gill opening. Pore formula 2–6–?–1. Pores of infraorbital series larger and more prominent than those of mandible (Fig. 59 a, b, c). Chin pores distinctly smaller than more posterior pores, well separated, their distance apart about 3% HL. Suprabranchial pore well above gill opening.

Pectoral fins about 3/4 head length; upper lobe reaching to about midpoint of abdominal cavity. Uppermost ray about even with middle of orbit. Upper lobe rounded, of 15 rays. Notch rays two, well separated short, filamentous, rudimentary. Lower lobe long, of four rays, reaching to below posterior tip of upper lobe; insertion of lowest ray below cheek. A clear gap present between lower fin lobes, its distance equal to about 1/4 HL. Right pectoral girdle with 3 (2+0+1) moderately large round or rounded radials of similar diameter; R1 and R2 very close. R2 with small dorsal notch. Scapula large, more or less hemicircular, its dorsal edge slightly convex, helve completely absent. Coracoid T-shaped, helve long, slender, ventral notch present at its base.

Body behind head much deeper, almost hump-backed, laterally compressed, deepest over mid-abdomen. Dorsal fin insertion between vertebrae 9–10, anal fin insertion between vertebrae 15–16. Dorsal and anal fins low anteriorly, gradually increasing in depth posteriorly, deepest caudally at about 80% of SL. Anus below tip of opercle, approximately below middle of pectoral fin base. Peritoneum clearly visible through body wall. Body cavity deep, long, dorsally humped above pectoral fin base. Hypural complex fused, slit absent. Caudal fin of seven (3/4) rays, auxiliary rays absent. Pyloric caeca about six, of various lengths. SECM probably well developed. Skin thick, strong.

Fresh color rosy, pinker caudally. Head and pectoral fin dusky gray, dorsal and anal fins anteriorly dark (Fig. 59). Color of body in alcohol pale rose, snout and area around mouth darker grayish, lower pectoral fin lobes and anal area blackish. Mouth dusky purplish grey, tongue pale with dotted melanophores. Branchial cavity blackish. Black peritoneum visible through body wall. Stomach and pyloric caeca pale except for black remnants of possible blood vessels on stomach.

The holotype has eggs up to 4.2 mm diameter.

Distribution. Known only from the holotype, taken at 1954–1990 m off the NW edge of Mawson Bank, Ross Sea.

Etymology. Nullansa from the Latin null, none, and ansa, helve, to denote the absence of a scapular helve in this species.

Comparisons. Paraliparis nullansa is very similar to, but distinct from, Paraliparis neelovi and Paraliparis voroninorum (see below for comparison with the latter). It differs from the former in having fewer dorsal fin rays (60 vs 61–66), more posterior dorsal fin insertion (between vertebrae 9–10 vs between 4–7), more caudal fin rays (7 vs 6), shorter snout to anus distance (97 vs 117–119% HL), no scapular helve (vs well developed), a notched R2 (vs none notched) and a basal coracoid notch (vs absent). It also similar to P. camilarus in counts and many proportions, but differs in number of vertebrae (71 vs 68), eye size (17 vs 22% HL), interorbital width (39 vs 50% HL), gill opening (3 vs 2% SL, 15 vs 10% HL), preanal length (242 vs 271% HL), and anus to anal fin distance (152 vs 180% HL).