Paraliparis voroninorum, Stein, 2012

Stein, David L., 2012, Snailfishes (Family Liparidae) of the Ross Sea, Antarctica, and Closely Adjacent Waters 3285, Zootaxa 3285, pp. 1-120 : 107-112

Paraliparis voroninorum n. sp.

Figs. 77, 78

Holotype. NMNZ P.043717, female, 318 mm TL, 295 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.043717/1, cleared and stained right pectoral girdle.

Diagnosis. V 69, D 62, A 56, C 6, P 20, notch rays 3, rudimentary. Radials 3 (2+0+1) or 4 (3+1) if R2 normal; scapular helve almost absent. Eye 18% HL, upper jaw 42% HL. Premaxillary teeth about 20 in outer row on each side, uniserial for posterior 9–10, mostly triserial for anterior 10 rows; lower jaw teeth almost entirely uniserial, distinctly smaller than upper jaw teeth, extending posteriorly much farther, easily visible near symphysis. Opercular flap clearly present. Pectoral fin short, 66% head length.

Description. Counts. V 69 (12+57), D 62, A 56, C 6, P 20 (14+3+3), radials 3 (but see below), pc 6, pore formula unknown. Ratios. HL 16.4, HW na, sn 4.8, E 3.0, orbit 4.7, io 7.2, uj 6.8, go 2.0, preD 26.1, preA 46.0, sna 17.0, ma 14.7, aAf 30.4, UPL 10.8, LPL 10.2. In % HL: HW na, sn 29.1, E 18.4, orbit 28.7, io 43.6, uj 41.7, go 12.2, ma 89.7, preD 159.5, preA 280.4, sna 103.5, aAf 185.5, UPL 66.1, LPL 62.2, LLD ~20, cp 2.7.

Head short, less than 1/6 SL, low, dorsal profile flat and gradually rising from snout to postorbital region. Snout short, bluntly rounded, projecting slightly beyond upper jaw. Nostrils short tubular, more or less on horizontal through mid-pupil, about 1/2 eye diameter anterior to orbit. Mouth horizontal, subterminal, lower jaw inferior, broadly rounded, included; oral cleft extending to below anterior half of orbit. Teeth simple, sharp, evenly spaced canines, arranged uniserially for most of jaw length. Premaxillary teeth about 20; in a single row of about nine, then becoming irregularly triserial towards symphysis, becoming gradually smaller anteriorly; posterior teeth stout, sharp, anterior teeth small but easily visible at 25x magnification. Mandibular teeth extending notably farther posteriorly, distinctly smaller, more closely spaced and more numerous than premaxillary teeth, 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 about equal to snout, not entering dorsal profile of head but approaching it, less than 1/3 HL. Gill opening completely above pectoral fin base, barely reaching to upper pectoral fin ray, about 12% HL. Opercular flap present, small but distinct; opercle broad, its tip supporting flap. Pore formula unknown. Chin pores distinctly smaller than more posterior pores, well separated, their distance apart less than 3% HL. Suprabranchial pore single.

Pectoral fins about 2/3 head length; upper lobe reaching to about midpoint of abdominal cavity. Uppermost ray about even with lower margin of orbit. Upper lobe rounded, of 14 rays. Notch rays rudimentary, three, well separated, increasingly short ventrally; lowest ray reduced to base only. Lower lobe long, of three rays, reaching to below middle of upper lobe; insertion of lowest ray below posterior of orbit. A clear gap present between lower fin lobes, distance equal to about 1/5 HL. Right pectoral girdle with 4 (3+1) moderately large round or rounded radials;

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FIGURE

R2 much smaller than other three, almost certainly abnormal, located between and anterior to R1 and R3 and very close to them. If R2 abnormal, radial formula would be 3 (2+0+1). No radial notches present. Scapula large, more or less triangular, its dorsal edge clearly concave, helve almost completely absent, its ventral edge with a broad, shallow concavity. Coracoid T-shaped, helve long, slender, ventral basal notch absent.

Body behind head dorsoventrally flattened, deepest behind head over mid-abdomen. Dorsal fin insertion between vertebrae 5–6, anal fin insertion between vertebrae 12–13. Dorsal and anal fins low anteriorly, gradually increasing in depth posteriorly, deepest caudally at about 2/3 of SL. Anus below gill flap, approximately below middle of pectoral fin base. Peritoneum dimly visible through body wall. Body cavity deep, long, dorsally humped above pectoral fin base. Hypural complex fused, slit absent. Caudal fin of six (3/3) rays, auxiliary rays absent. Pyloric caeca six, matted and firmly attached to each other, very long, up to 3/4 HL. SECM probably well developed. Skin thick, strong.

Color of body in alcohol white, snout and area around mouth apparently grayish brown; posterior half of dorsal and anal fins edged with brown. Mouth blackish, tongue dusky with closely dotted melanophores. Branchial cavity blackish. Black peritoneum barely visible through body wall. Stomach and pyloric caeca pale.

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

Etymology. Paraliparis voroninorum is named in honor of Elena Voronina and Vladimir Voronin, who by their kindness, generosity, and hospitality over many years helped support my snailfish research at the Zoological Institute of the Russian Academy of Sciences, St. Petersburg.

Comparisons. Paraliparis voroninorum is very similar to, but distinct from, P. nullansa and P. neelovi . It could easily be confused with the former on the basis of most counts and proportions, its 3 (2+0+1) radials, and its scapula lacking a helve. However, P. voroninorum differs distinctly from it externally in having a small opercular flap (vs absent) with a broad opercle (vs narrow), paler color (white vs darker, rosy), small (but not tiny) premaxillary teeth anteriorly (vs tiny anterior teeth), and 6 (vs 7) caudal fin rays. Internally it differs in having the dorsal fin insertion between vertebrae 5–6 (vs 9–10) and anal fin insertion between vertebrae 12–13 (vs between 15–16), radials R1 and R2 much farther apart, unnotched R2 (vs dorsally notched), and coracoid without basal notch (vs

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FIGURE with). Although very similar to the latter, P. voroninorum differs from it in lacking a scapular helve (vs well developed), fewer lower lobe rays (3 vs 4), a smaller eye (18.4 vs about 20–24% HL), longer upper jaw (42 vs ~35% HL), shorter snout to anus distance (103.5 vs 117–120% HL), and anus anterior to gill opening (vs below it).

Comments. The arrangement of pectoral radials in the right pectoral girdle of this specimen is unusual and anomalous. Normally, all radials are on a gently curved line, and not misaligned like R2, which appears to be “extra.” Fortunately, other characters define this species as new. As described and discussed above, some other recently described Southern Ocean species also have odd radial patterns ( P. hureaui , P. charcoti , P. kocki , P. stehmanni ). If R2 is anomalous, P. voroninorum would normally have 3 (2+0+1) radials.