Paraliparis exilis, 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 : 23-25

Paraliparis exilis n. sp.

Figs. 18 , 19

Holotype. NMNZ P.047284, female?, 120 mm SL, 129 mm TL, 43°42.375ʹ S, 174°10.158ʹ W, southeastern Chatham Slope, R/V Tangaroa, Stn. TAN 0709/099, 20 July 2007, 1086 m. NMNZ P.047284/1, cleared and stained right pectoral girdle.

Diagnosis. Vertebrae 66, dorsal fin rays 60, anal fin rays 54, caudal fin rays 8, pectoral fin rays ~20. Teeth forming broad bands of 28–30 obliquely curved rows, nowhere uniserial; on premaxilla shouldered, on mandible, simple canines. Chin pores paired, very closely set with a possible tissue fold anteriorly but not in a pit. Gill opening completely above pectoral fin, short, about 16% HL. Pectoral radials 4 (3+1); scapula and R1, R3 clearly notched. Snout to anus distance short, 14% SL, about 70 % HL. Anus to anal fin distance less than 120% HL.

Description. Counts. V 66, D 60, A 54, C 8, P ~20, radials 4, pc ≥ 2. Ratios. HL 19.1 % SL, HW na, sn 5.7, E 4.2, orbit 6.0, uj 8.5, go 3.1, UPL 15.8, LPL 11.2, bd ~15, bdA 13.2, preD 26.3, preA 34.7, sna 13.7, ma 12.0, aAf 22.5, mabd 32.9, pabd ~23. In % HL: HW na, sn 29.7, E 21.8, orbit 31.4, uj 44.5, go 16.2, UPL 83.0, LPL 59.0, bd ~77, bdA 69.4, preD 138.0, preA 181.6, sna 71.6, ma 62.9, aAf 117.9, mabd 172.5, pabd ~122.

Head small, low, about 1/5 SL, its dorsal profile almost straight, rising gradually to occiput. Snout short, blunt, slightly protruding above mouth. Nostrils single with raised rims, about on horizontal through mid orbit. Mouth terminal, small, horizontal, oral cleft reaching to below anterior margin of eye, upper jaw reaching to below rear of pupil. Premaxillary teeth small shouldered canines, inner teeth largest, arranged in about 30 obliquely curved rows of up to 12 teeth each, forming a broad band anteriorly; dentary teeth stout simple canines lacking shoulders, arranged similarly to premaxillary teeth. Eye moderately large, less than 1/4 HL, dorsal margin of orbit near dorsal profile of head. Gill opening completely above pectoral fin, short, much less than diameter of eye. Opercular flap sharply tipped, supported by broad, dorsally curved opercular spine. Pore counts unknown owing to damage; chin pores small, oval, very close together, distance between pm1-pm1 much less than that between pm1-pm2 on each side. Other mandibular pores similar in size, not easily visible against black skin.

Pectoral fins well developed, upper ray about on a horizontal through lower margin of orbit. Pectoral rays about 20 (14–15+2+3–4) on each side (right side notch rays missing), longest ray of upper lobe reaching posteriorly almost to anal fin origin, about 80% length of abdominal cavity. Notch deep, including two short, well developed rays, rudimentary rays absent. Lower lobe of 3–4 clearly exserted rays, reaching about 1/3 of upper lobe length, not reaching middle of abdominal cavity. Pectoral girdle radials 4 (3+1), round, R1 dorsally notched, R2 with shallow ventral indentation, R3 dorsally notched, a wide gap present between R3 and much smaller R4. Scapula with a deeply notched base and another opposite dorsal notch in R1, almost three-lobed; coracoid with long slender helve, basal notch absent.

Body slender, its depth behind head no greater than head depth, evenly tapered to caudal. Vertebrae 10+56. Predorsal length about 1/4 SL, first two dorsal pterygiophores not bearing rays, first ray between vertebrae 4–5. Anal fin origin between vertebrae 11–12. Preanal fin length about 1/3 SL. Dorsal and anal fins broadest at about half body length. Anus below edge of preopercle, distinctly anterior to vertical through gill opening. Abdominal cavity long. Stomach large, muscular. Pyloric caeca two or more, flattened, thin walled. Hypural fused, slit not evident in radiograph. Caudal fin rays 4/4. Skin thin but not easily damaged.

Fresh color evenly black all over. In alcohol, entire body and fins dense black. Orobranchial cavity pale, heavily dotted with melanophores, peritoneum black, pyloric region of stomach black streaked, remainder pale, pyloric caeca pale.

Distribution. Known only from the holotype, taken on the southeast Chatham slope off New Zealand at a depth of 1086 m.

Etymology. The specific epithet exilis , thin, from the Latin, denoting the species slender elongated body.

Comparisons. Most similar to P. freeborni ; see that species for comparison. In comparison to Australian Paraliparis species with four radials (see Stein et al. 2001), P. exilis differs from all of them in having a shallower body depth (~15 vs 16–23% SL, ~77 vs 90–132% HL), narrower interorbital space (37 vs 38–54% HL), shorter gill opening (16 vs 19–22% HL), and a longer upper pectoral fin lobe (16 vs 12–14% SL). Additionally, there are other differences from the individual species.

Comments. The new species is the only Paraliparis occurring in New Zealand waters having four radials, and the only one with notched radials. Paraliparis species with similar pectoral girdle characters are also known from the Ross Sea, Antarctica.

Figures

FIGURE 18. Paraliparis exilis n. sp. Holotype. NMNZ P. 047284, 120 mm SL. A. lateral view; B. NMNZ P. 047284 / 1, right pectoral girdle.

FIGURE 19. Paraliparis exilis n. sp. Holotype. NMNZ P. 047284, 120 mm SL. Lateral view of fresh specimen. (Photo by P. Marriott, NIWA)