Pavoraja pseudonitida, Last, Peter R. & Yearsley, Stephen Mallick And Gordon K., 2008
treatment provided by
Pavoraja pseudonitida sp. nov.
( Figs 1View FIGURE 1 e, 2 e, 17 –19, 20a –c, Tables 3, 4)
Pavoraja sp. E: Last and Stevens, 1994, Sharks and rays of Australia, pp 318, fig. 34.12, key fig. 39, pl. 47; Last and Compagno, 1999, Arhynchobatidae , softnose skates. In: Carpenter and Niem (eds), 1999, FAO species identification guide for fisheries purposes. The marine living resources of the Western Central Pacific, pp 1461, figs.
Holotype. CSIRO H 438 –01, 372 mm TL, adult male, Saumarez Plateau, Queensland, 22 ° 46 ' S, 154 °08' E, 445–450 m, 17 Nov. 1985.
Paratypes. 39 specimens (152–370 mm TL): AMS I 25827View Materials –007 (6 specimens), 273 mm TL, juvenile male; 274 mm TL juvenile male; 278 mm TL juvenile male; 288 mm TL juvenile male; 276 mm TL female; 289 mm TL female, north of Townsville, Queensland, 18 °03' S, 147 °09' E, 300 m, 17 Jan. 1986; CSIRO H 436 –01, 321 mm TL, female; CSIRO H 437 –01, 324 mm TL, female; CSIRO H 439 –01, 347 mm TL, adult male; CSIRO H 440 –01, 324 mm TL, juvenile male; CSIRO H 441 –01, 346 mm TL, adult male; CSIRO H 442 –01, 344 mm TL, female; CSIRO H 443 –01, 321 mm TL, adult male; CSIRO H 444 –01, 255 mm TL, juvenile male; CSIRO H 445 –01, 319 mm TL, juvenile male; CSIRO H 446 –01, 205 mm TL (tail damaged), juvenile male, collected with holotype; CSIRO H 600 –01, 357 mm TL, female, Saumarez Plateau, Queensland, 22 ° 44 ' S, 154 ° 12 ' E, 492 m, 17 Nov. 1985; CSIRO H 602 –01, 324 mm TL, female; CSIRO H 602 –03, 229 mm TL, female; CSIRO H 602 –04, 226 mm TL, juvenile male; CSIRO H 602 –05, 250 mm TL, female; CSIRO H 602–24, 220 mm TL, juvenile male, Saumarez Plateau, Queensland, 22 ° 40 ' S, 154 °05' E, 416–421 m, 17 Nov. 1985; CSIRO H 630 –03, 370 mm TL, adult male, Saumarez Plateau, Queensland, 22 ° 35 ' S, 153 ° 46 ' E, 345–350 m, 17 Nov. 1985; CSIRO H 643 –01, 192 mm TL (tail damaged), juvenile male, northeast of Whitsunday Group, Queensland, 19 ° 38 ' S, 150 ° 33 ' E, 312–318 m, 15 Nov. 1985; CSIRO H 644 –01, 298 mm TL, female; CSIRO H 644 –02, 281 mm TL, female, Saumarez Plateau, Queensland, 22 ° 46 ' S, 154 °08' E, 445–450 m, 17 Nov. 1985; CSIRO H 645 –01, 277 mm TL, juvenile male, south-east of Swain Reefs, Queensland, 22 ° 59 ' S, 152 ° 57 ' E, 343–350 m, 18 Nov. 1985; CSIRO H 646 –01, 287 mm TL, female; CSIRO H 646 –02, 280 mm TL, female; CSIRO H 646 –03, 277 mm TL, juvenile male, Swain Reefs, Queensland, 21 ° 20 ' S, 153 ° 32 ' E, 502 m, 20 Nov. 1985; CSIRO H 647 –01, 285 mm TL, female, south of Marion Reef, Queensland, 19 ° 44 ' S, 152 ° 12 ' E, 406–435 m, 23 Nov. 1985; CSIRO H 648 –01, 264 mm TL, female; CSIRO H 648 –02, 326 mm TL, adult male; CSIRO H 648 –03, 339 mm TL, adult male; CSIRO H 648 –04, 227 mm TL, juvenile male, east of Townsville, Queensland, 18 ° 59 'S, 149 ° 28 ' E, 452–453 m, 26 Nov. 1985; CSIRO H 649 –01, 315 mm TL, female, off Townsville, Queensland, 17 ° 55 ' S, 147 °05' E, 340–348 m, 29 Nov. 1985; CSIRO H 650 –01, 343 mm TL, juvenile male, north-east of Hinchinbrook Island, Queensland, 17 ° 54 ' S, 146 ° 56 ' E, 212 m, 9 Dec. 1985; CSIRO H 720–10, 152 mm TL, juvenile male, south of Saumarez Reef, Queensland, 23 ° 12 ' S, 153 ° 37 ' E, 399–405 m, 18 Nov. 1985; CSIRO H 3464 –01, 196 mm TL, juvenile male, Marian Plateau, Queensland, 18 ° 57 ' S, 149 ° 31 ' E, 494–512 m, 26 Nov. 1985.
Diagnosis. A species of Pavoraja with: a relatively long tail, length 53–61 % TL, width at midlength 1.4– 2.2 % TL; relatively narrow interorbital space, width 2.4–3.2 % TL; narrowly spaced gill slits, width between first fill openings 10.5–13.7 % TL; orbital thorns large, mostly 3 on posteromedial margin; interorbital thorns sometimes present; spiracular thorns absent; scapular thorns rarely present; nuchal pore patch indistinct, not preceded by a nuchal thorn; thorns of tail series large, decreasing in size posteriorly, often absent immediately before first dorsal fin; interdorsal space short, fins rarely connected; epichordal lobe of caudal fin not confluent with second dorsal fin, base of lobe variable in length, generally shorter than dorsal-fin bases; tooth rows in lower jaw 37–46; predorsal caudal centra 76–81; interdorsal vertebrae 9–13; pectoral radials usually 72–75 (one paratype has 69); dorsal surface yellowish, usually densely covered with small, unclustered pale spots; dorsal fins mostly pale anteriorly, dark posteriorly; epichordal lobe uniformly pale, strongly demarcated from dorsal fins; ventral surface usually uniformly white.
Description. Disc 1.16 (1.10–1.20) times as broad as long; maximum angle in front of spiracles 99 ° (90– 103 °); anterior margin weakly double concave to almost straight in females and immature males, mostly deeply concave opposite spiracles in males; posterior margin strongly convex; outer corners broadly rounded. Snout width at axis through anterior border of orbits 62 % (60–64 % in mature male, 69–79 % in female paratypes) of distance from tip of snout to axil of pectoral fins. Pelvic-fin anterior margin 66 % (64–77 % in mature male, 76–88 % in female paratypes) of distance from origin of anterior lobe to posterior extremity of fin. Tail length 1.21 (1.09–1.42) disc length; widths at midlength and at axils of pelvic fins 50 (33–50) and 113 (81–115) of orbit diameter respectively; narrow skin fold extending along ventrolateral surface from near (mostly just behind) pelvic-fin tip to near origin of hypochordal lobe of caudal fin, widest under dorsal fins (subequal in height to epichordal lobe of caudal fin). Interdorsal distance mostly short, fins rarely connected, much less than half length of first dorsal-fin base (subequal to first dorsal-fin base in CSIRO H 650 –01); base length of epichordal caudal-fin lobe variable but generally shorter than bases of dorsal fins, separated slightly from base of second dorsal fin.
Preocular length 2.50 (2.29 –3.00) times longer than orbit diameter; preoral length 2.21 (2.28–2.85) times internarial distance. Orbit diameter 1.45 (1.40 –2.00) times interorbital distance; 1.60 (1.40 –2.00) times length of spiracles. Internarial distance 1.46 (0.39–0.50) in distance between first gill slits; 0.86 (0.61–0.90) in distance between fifth gill slits. Length of first gill slit 1.33 (1.00– 1.67) times length of fifth gill slit; 0.17 (0.13– 0.23) in mouth width.
Dorsal surfaces of disc and tail densely covered with fine denticles, less so on posterior lobes of pelvic fins. Dorsal fins weakly denticulate. Claspers, anterior lobes of pelvic fins, skin folds on tail, caudal lobes and entire ventral surface naked. Orbit with 1–5 (mostly 3 or 4) thorns on anteromedial margin, 2–5 (mostly 3) on posteromedial margin; these series almost connected, rarely with one thorn on medial margin; rarely with a single interorbital thorn; interspiracular thorns absent. Prenuchal and nuchal thorns variable, 0–5 (mostly 2 or 3), situated posterior to pale, pored prenuchal area; often absent in juveniles; smaller peripheral nuchal thorns and scapular thorns absent. Tail with rather large, widely spaced thorns arranged in 1–3 series; thorns decreasing in number and size posteriorly; dorsolateral series mostly absent from posterior half of tail; rarely extending anteriorly onto disc in juveniles and adult males (largest females with 2–4 rows of enlarged thorns extending forward almost to mid disc); median series originating over cloaca or slightly behind, continuous but less well developed in predorsal area than on anterior tail; interdorsal thorns absent. Adult males with 1–2 (mainly 1) regular rows of small non-retractable alar thorns, not developed into dense patch of irregularly shaped thorns; malar thorns slightly smaller, directed posteriorly; malar patch very broad, extending along most of outer pectoral corner (from immediately behind greatest concavity of anterior margin of disc to level of pectoral-fin insertion). Smallest juvenile ( CSIRO H 720 – 10) with 1 small anteromedial orbital thorn, 1–2 posteromedial orbital thorns; nuchal thorns absent; median row of tail thorns barely larger than surrounding denticles.
Claspers slender ( Figs 20View FIGURE 20 a –c); pseudorhipidion continuing distally under sentinel as fold of integument, finally becoming fused to glans floor; slit lateral to distal portion of pseudorhipidion; spur well developed, poorly defined proximally, distal tip lying slightly inside glans margin; rhipidion poorly developed, extending from proximal third to middle of glans, seldom reaching base of sentinel; sentinel well developed, rod-shaped with rounded distal margin, covered with integument that is thicker and more fleshy laterally, extending from level of slit to tip of glans; spike just visible within sentina; axial cartilage straight, very slender; dorsal marginal slightly expanded distally; pseudorhipidion blade-like over middle third, thinning to a sharp point distally; ventral marginal with an evenly convex distal margin; dorsal terminal 1 and ventral terminal tightly joined on ventral aspect of glans, together forming sheath-like covering over central half of glans; dorsal terminal 1 membranous (though well defined), deeply corrugated, proximal and distal margins jagged; ventral terminal corrugated, membranous, thickened area immediately distal to moderately short proximal arm, penetrating glans and lying against dorsal margin of proximal extension of accessory terminal 1, distolateral margin with sharp serrations; dorsal terminal 2 with poorly defined cartilaginous projection joined to axial near level of accessory terminal 2 base by connective tissue (incomplete terminal bridge), outer lateral margin with fine serrations; dorsal terminal 3 moderately large; accessory terminal 1 with a bow-shaped distal extension forming sentinel, almost reaching distal margin of accessory terminal 2.
Neurocranium of CSIRO H 442 –01 typical of genus; with no free accessory lateral cartilages but rostral appendices with small foramina; 2 large foramina near apex of rostral node; rostral shaft elongate, subequal in length to basal fenestra; posterior fontanelle much longer than anterior fontanelle.
Scapulocoracoid with 2–3 postventral foramina; central foramen smallest when present.
Meristics (n= 10). Tooth rows in upper jaw 41 (38–46), in lower jaw 41 (37–46). Vertebral counts: monospondylous centra 27 (26–30), predorsal caudal centra 78 (76–81), interdorsal centra 12 (9–13), diplospondylous centra 113 (106–117), total centra 140 (133–146). Pectoral-fin counts: propterygial radials 33 (32–35), mesopterygial radials 12 (12–14), metapterygial radials 27–28 (25–29), total radials 72–73 (72–75, one nonspotted specimen CSIRO H 630 –03 had 69). Pelvic-fin counts: males 4 (3–4) + 19 (18–20) radials, females 3– 4 + 18–20 radials.
Coloration. Preserved and live colour similar. Dorsal surface of disc, tail and posterior lobes of pelvic fins uniform yellowish brown or pale brown; disc variably spotted, usually with a dense arrangement of small nonclustered white spots (some specimens, juveniles and some large females, lacking spots); spots relatively sharp-edged, sometimes surrounded by slightly darker rim; spots less dense or absent on tail and posterior pelvic lobes, where present rarely extending past posterior pelvic insertion; pale nuchal pore patch weak or absent; mid area of snout and outer part of disc generally paler than central part of disc, somewhat translucent; anterior pelvic lobe usually white; membrane covering orbits semi-translucent, lightly pigmented; lateral skin fold white, strongly demarcated from darker dorsal surface of tail posteriorly. Clasper not uniformly pigmented dorsally, proximal half paler than distal half, posterolateral tip of glans white. Dorsal fins two-toned pale or white anteriorly, dusky or almost black posterodorsally. Epichordal lobe of caudal fin uniformly pale, strongly demarcated from dorsal fins. Ventral surface mostly uniform white to semi-translucent, occasionally with yellowish to greyish areas centrally or near outer corners of disc. Smallest juveniles (less than 200 mm TL) either plain or white spotted with weak evidence of slightly darker tail bands; dorsal fins strongly demarcated from rest of tail; ventral surface translucent.
Size. At least 372 mm TL and about 205 mm disc width. Smallest mature male 321 mm TL. Post-natal by 152 mm TL.
Distribution. Known from the upper continental slope off Queensland, between the outer reef north of Townsville (17 ° 55 ' S, 147 °05' E) and south of the Saumarez Reef (23 ° 12 ' S, 153 ° 37 ' E), in depths of 212– 512 m.
Etymology. Combination of the Greek pseudos (false) with the Latin nitidus (elegant) in allusion to the superficial resemblance to its congener, Pavoraja nitida .
Comparisons. Along with Pavoraja nitida and P. m o s a i c a, this species can be distinguished from other consubgeners by the presence of a pattern of white spots on the dorsal surface of the disc. Apart from the additional characters provided in the key and diagnoses, P. pseudonitida differs from P. nitida in the appearance of the spotted pattern (spots spaced well apart rather than in clusters), and in having more teeth rows in the lower jaw (37–46 rather than 31–36) and more predorsal caudal centra (76–81 rather than 62–70). Pavoraja mosaica has a more distinctive and richer colour pattern, a shorter tail (51–53 % rather than 53–61 % TL), the second dorsal fin and epichordal lobe are confluent (rather than separated), and lacks interorbital, nuchal, prenuchal and scapular thorns (often present in P. pseudonitida ).
Remarks. P. pseudonitida belongs to the Cape and North Eastern marine biogeographic provinces of Australia where it is found primarily in the upper slope biome ( Last et al., 2005).
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