Psednos chathami, 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 : 36-37

Psednos chathami n. sp.

Fig. 27

Holotype. NMNZ P.025387, ripe male, 87 mm SL, 99 mm TL, 42°37.00' S, 175°36.40' E, northwest Chatham Rise, F/V Otago Buccaneer, Stn. OBS 0380/123, 22 September 1989, 1335– 1340 m.

Diagnosis. Dorsal fin rays 52 or 53, anal fin rays 45 or 46, pectoral fin rays 16–17, eye 26%, preA 157%, snout 17%, upper jaw ~50% HL. Occipital hump prominent. Teeth slender canines, premaxillary symphyseal gap very narrow, mandibular symphyseal gap absent. Opercle curved, posterior part almost horizontal. Distance from mandible to end of body cavity 36% SL, 154% HL. Coronal pore probably absent.

Description. Counts: V 59, D 52 or 53, A 45 or 46, C unknown, P 16–17, radials unknown, gr 12/9, pc 8, pore formula unknown. Ratios: HL 23.3% SL, sn 4.0, E 6.1, orbit 6.8, io 9.4, uj 11.8, go 5.6, UPL 15.2, LPL 13.9, preD 29.7, preA 36.6, sna 20.6, ma 19.5, aAf ~23, mabd 35.9, pabd 21.3. In % HL: sn 17.2, E 26.1, orbit 29.1, io 40.4, uj 50.7, go 24.1, UPL 65.5, LPL 59.6, preD 127.1, preA 156.6, sna 88.2, ma 83.7, aAf ~99, mabd 153.7, pabd 91.1.

Dorsal profile of head rises steeply and evenly to prominent occipital hump. Snout posterior to mandibular symphysis. Nostrils single, about on horizontal with top of pupil, close to anterior margin of orbit. Mouth oblique, its angle about 30°, upper jaw included, its symphysis anterior to snout. Mandibular symphysis strong but lacking a prominent knob. Premaxillary teeth slender canines, inner teeth larger and sharper than outer ones, forming a narrow band of about 25 oblique rows of up to 7 teeth each; teeth apparently more closely set than in lower jaw. Narrow symphyseal gap present. Mandibular teeth larger and longer than premaxillary teeth, the largest innermost and nearest symphysis, slender with rounded tips; more posterior teeth sharp, lanceolate, forming a narrow band of about 25 oblique rows of up to 6 teeth each, the band gradually and slowly increasing in width anteriorly; symphyseal gap absent. Eye large, prominent, slightly more than 25% HL; orbit almost 30% HL. Gill opening above pectoral fin and extending ventrally in front of 1–2 fin rays, most of its length below opercular spine. Gill rakers on first arch 12/9, dorsal ones alternating, ventral rakers opposite. Spinules forming a V-shaped patch on each raker, generally with no clear pattern but a few rakers with two clear rows within more numerous scattered spinules. Opercle strongly curved posteroventrally, its posterior part almost horizontal and on a level with midline of body. Pore formula unknown, coronal pore apparently absent; symphyseal pores missing.

Pectoral fin dorsal ray about on horizontal with posterior corner of mouth. Pectoral fin rays 8+3+6 (R), 7+4+5 (L), upper lobe reaching just behind abdominal cavity; rudimentary notch rays absent, not reaching midpoint of upper lobe. Notch moderately deep, its rays more widely spaced than those in upper and lower lobes, upper lobe rays more distinct from notch rays than lower lobe rays. Lower lobe almost as long as upper lobe, but its base sharply angled and much farther anterior. Pectoral girdle not examined.

Trunk deep anteriorly, occipital hump high and sharply curved; highest and deepest point of body just anterior to gill flap. Vertebrae 11+48, first four vertebrae forming a very tight arc manifested externally by the high, prominent hump. Dorsal fin origin between vertebrae 4–5, anal fin origin between vertebrae 10–11. Anus notably posterior to pectoral symphysis and distant from it by about 1/3 lower fin lobe length; a long, slender, fragile genital papilla present just posterior to anus. Abdomen short, length from mandibular symphysis a little less than 1/3 SL, 1.5 times HL. Pyloric caeca digitate, fat, of differing lengths, very short to moderately long. Hypural complex completely fused, no slit evident. Caudal rays unknown, all rays missing. Skin thin, fragile, transparent.

Life color unknown. Color of body in alcohol pale, skin whitish transparent, fins slightly brown, mouth and tongue brown spotted, branchial cavity dusky; peritoneum very dark brown, visible through body wall as black. Stomach blackish, pyloric caeca pale.

Distribution. Known only from the holotype, taken in midwater at about 1335 m on the Chatham Rise East of New Zealand.

Etymology. The specific epithet chathami denoting the locality of collection.

Comparisons. Psednos chathami is most likely to be confused with P. n e m n e z i and P. platyoperculosus . See those descriptions for differences. Psednos chathami is also similar to Psednos sp. of southeastern Australia ( Stein et al. 2001) but differs distinctly in number of dorsal fin rays (53 vs 48), number of anal fin rays (45–46 vs 43), snout length (17 vs 26% HL), orbit diameter (29 vs 35% HL), unequal jaw lengths (upper and lower jaws 51 and 62% HL, respectively, vs 48% HL), and longer snout to anus distance (88 vs 82% HL).

Figures

FIGURE 27. Psednos chathami n. sp. Holotype. NMNZ P. 025387, 87 mm SL. A. lateral view; B. first gill arch; C. spinules on rakers.