Psednos nemnezi, Stein, David L., 2012

Stein, David L., 2012, A Review of the Snailfishes (Liparidae, Scorpaeniformes) of New Zealand, Including Descriptions of a New Genus and Sixteen New Species, Zootaxa 3588, pp. 1-54 : 44-46

Psednos nemnezi n. sp.

Figs. 33 , 34

Holotype. NMNZ P.025435, ripe male, 90 mm SL, 100 mm TL, 43°15.5' S, 173°58.1' E, Pegasus Canyon, northeast of Banks Peninsula, R/V James Cook, Stn. JCO 8910/010, 12 October 1989, 932– 960 m.

Paratype. NMNZ P.027097, ripe? male, 84 mm SL, 94 mm TL, 44°24.52' S, 175°04.56' W, south Chatham Rise, F/V Cordella, Stn. COR 9004/119, 16 November 1990, 832– 852 m (skinned).

Diagnosis. Vertebrae 58–59, pectoral fin rays 16, pyloric caeca 6–10. Occipital hump prominent. Mouth angle about 60°. Premaxillary teeth tiny, slender, sharp canines with slight shoulders, in a narrow band of about 40 oblique rows of up to 7 teeth each. Gill opening short, above pectoral and in front of 1–2 rays, its length less than 1/5 HL. Opercle a broad swordlike blade extending ventrally with a shallow curve posteriorly, its tip a sharp spine reaching posterior to pectoral fin base. Symphyseal pores without raised rim, small, widely separated, fragile. Coronal pore absent. Rays of upper and lower pectoral fin lobes free for a significant proportion of their length. Abdominal cavity length behind pectoral symphysis about 20% SL, almost equal to HL.

Description. Counts: V 59 (58), D 51 (49 or 50), A 44 (43), C 6, P 16 (16), radials unknown, gr 10/8 (9/8), pc 10 (6), pores unknown. Ratios: HL 21.9 (23.2)% SL, HW ~14 (15.7), sn 4.1 (6.4), E 4.6 (4.5), orbit 6.3 (6.4), io 10.9 (12.0), uj 11.3 (11.4), go 3.9 (na), UPL 14.3 (10.1), LPL 12.4 (8.0), bd 30.9 (28.0), preD 27.8 (29.3), preA 37.0 (39.5), sna 20.2 (20.8), ma 19.4 (19.6), aAf 21.6 (21.5), mabd 33.4 (32.8), pabd 20.6 (21.7). In % HL: HW ~63 (67.7), sn 18.8 (27.7), E 20.8 (19.5), orbit 28.9 (27.7), io 49.7 (51.8), uj 51.8 (49.2), go 17.8 (na), UPL 65.5 (43.6), LPL 56.8 (34.4), bd 141.1 (120.5), preD 126.9 (126.2), preA 169.0 (170.3), sna 92.4 (89.7), ma 88.8 (84.6), aAf 98.5 (92.8), mabd 152.8 (141.5), pabd 93.9 (93.3).

Head short, deep; dorsal profile rising steeply and evenly at an angle of 50–60° to prominent occipital hump. Snout and symphysis of upper jaw slightly included, tip of mandible most anterior point of body. Snout short, low, about on horizontal with lower margin of orbit. Nostril single, not tubular, directly anterior to orbit on horizontal through middle of pupil. Eye relatively small, less than 1/20 SL, about1/5 HL, orbit well below dorsal profile of head. Mouth oblique, its angle about 60°, oral cleft short, reaching to below anterior margin of orbit; posterior of upper jaw below middle of orbit. Teeth tiny, slender, sharp canines with slight shoulders, arranged in about 40 oblique rows of up to 7 teeth each, forming a narrow band. A clear gap and notch present at premaxillary symphysis. Mandibular teeth similar to those in upper jaw, but generally larger and longer, especially innermost teeth; a very narrow but distinct gap present at symphysis, obscured by teeth crossing over it. Angle of retroarticular about 90°. Gill opening above pectoral and extending ventrally in front of 1–2 rays, its length less than 1/5 HL. Gill rakers on first arch about 10/8, generally alternating, but in paratype, ventralmost rakers are opposite. Spinule patches on rakers mostly triangular, but spinules in no recognizable pattern. Opercle a broad sword-like blade extending ventrally with a shallow curve posteriorly, its tip narrow, forming a spine with a strongly acute angle of about 30°, dividing gill membrane in two halves, extending well beyond margins of membrane on either side of it. Tip of spine distinctly posterior to bases of dorsalmost pectoral fin rays. Pores very small. Symphyseal pores without raised rim, small, widely separated, fragile. Coronal pore absent. Suprabranchial pore possibly double.

Pectoral fin dorsal ray about on horizontal with posterior corner of upper jaw and end of oral cleft. Pectoral fin rays 8+3+5. Upper lobe barely reaching end of body cavity, notch depth moderate, clearly less than 1/4 upper lobe length, rudimentary rays absent; lower lobe reaching less than half distance to end of upper lobe. Fin rays of upper and lower lobes distinctly more closely spaced than those in notch, free distally for a significant proportion of their length. Pectoral girdle not examined.

Trunk anteriorly deep, tapering evenly and rapidly to caudal. Occipital hump well developed; highest and deepest point of body almost directly above gill opening. Vertebral formula of holotype 12+47, of paratype 13+45, first three or four vertebrae forming a very tight dorsal arc manifested by the high, prominent hump. Neural spines of first three vertebrae of both specimens are thicker than those more posterior; those of paratype are double, but those of holotype are thicker and only the second is forked. Remaining neural spines single. Dorsal fin origin between vertebrae 5–6 (6–7), anal fin origin between vertebrae 12–13 (13–14). Anus distinctly posterior to pectoral symphysis by a short distance; a fragile genital papilla present just posterior to anus. Abdomen depth about 1/6 SL, less than HL. Intestine with two or three coils on right side mid abdomen. Pyloric caeca fat, digitate, bluntly pointed. Hypural complex completely fused, no slit evident. Caudal rays 3/3. Skin thin, fragile, transparent.

Fresh color evenly rosy except for darker branchial cavity and peritoneum visible through body wall. Color of body in alcohol whitish, head slightly brownish owing to visibility of branchial cavity through skin; mouth and tongue dusky, brown-spotted; branchial cavity dusky. Peritoneum brownish black, visible through body wall; stomach blackish brown, caeca blackish at base and black streaked, otherwise pale. Intestine similar except for pale coils.

Distribution. Known from two specimens taken on the Chatham Rise in different trawls at depths of 830– 960 m.

Etymology. The name nemnezi from the initials NMNZ, the National Museum of New Zealand Te Papa Tongarewa.

Comparisons. Psednos nemnezi is similar to four species in the region: P. chathami , P. cryptocaeca , P. platyoperculosus and P. struthersi . It differs from P. chathami most notably in eye size (20 vs 26% HL), interorbital width (50–52 vs 40% HL), preanal fin length (170 vs 157% HL), slightly longer snout (19–28 vs 17% HL), and opercle angle (pointing almost vertically downwards vs horizontal and posteriorly). Although P. n e m n e z i is easily confused with P. cryptocaeca , it differs in number of vertebrae (58–59 vs 56), distance from pectoral symphysis to abdomen end (19–22 vs 24% SL, 85–93 vs 120% HL), mandible to anus distance (85–89 vs 101% HL), anus to anal fin length (93–99 vs 116% HL), predorsal fin length in relation to head length (126 vs 140% HL), distance from mandible to abdomen end (141–153 vs 175% HL). For comparisons to P. platyoperculosus and P. struthersi , see those accounts below.

Figures

FIGURE 33. Psednos nemnezi n. sp. Holotype. NMNZ P. 025435, 90 mm SL. A. lateral view; B. first gill arch from holotype, NMNZ P. 025435; C. spinules on rakers.

FIGURE 34. Psednos nemnezi n. sp. Holotype. NMNZ P. 025435, 90 mm SL. Lateral view of fresh specimen. (Photo by P. McMillan, NIWA)