Pavoraja arenaria, Last, Peter R. & Yearsley, Stephen Mallick And Gordon K., 2008
treatment provided by
Pavoraja arenaria sp. nov.
( Figs 1View FIGURE 1 b, 2 b, 6 d –f, 7–9, Tables 1, 4)
Pavoraja sp. C: Last and Stevens, 1994, Sharks and rays of Australia, p 316, fig. 34.10, key fig. 40, pl. 45. Pavoraja sp. 2: Last in Gomon et al., 1994, The fishes of Australia’s south coast, p 160, fig. 137.
Holotype. CSIRO H 175 –01, 272 mm TL, juvenile male, Great Australian Bight, Western Australia, 33 ° 20 ' S, 128 ° 28 ' E, 357–377 m, 1 Mar. 1980.
Paratypes. 23 specimens (128–343 mm TL): CSIRO H 171 –01, 307 mm TL, female, Great Australian Bight, Western Australia, 33 ° 22 ' S, 128 °00' E, 320–339 m, 14 Mar. 1980; CSIRO H 173 –01, 288 mm TL, adult male, Great Australian Bight, South Australia, 33 ° 25 ' S, 129 ° 35 ' E, 340–400 m, 3 Aug. 1981; CSIRO H 174 –01, 307 mm TL, female, Great Australian Bight, South Australia, 33 ° 20 ' S, 130 ° 12 ' E, 192–200 m, 3 Aug. 1981; CSIRO H 1818 –01, 275 mm TL (tail damaged), female, south of Cape Leeuwin, Western Australia, 34 ° 59 ' S, 114 ° 53 ' E, 712 m, 23 Dec. 1989; CSIRO T 1240, 257 mm TL, female, Great Australian Bight, South Australia, 33 ° 31 ' S, 129 ° 35 ' E, 456–524 m, 25 Feb. 1980; NMV A 596, 222 mm TL, juvenile male; NMV A 597 (3 specimens), 280 mm TL, juvenile male, 294 mm TL, juvenile male and 330 mm TL, adolescent male, Bass Strait, off Portland, Victoria, 38 ° 40 ' S, 141 ° 15 ' E, 15 May 1979, 293– 329 m, 15 May 1979; NMV A 2164, 332 mm TL, female, off Beachport, South Australia, 37 ° 51 ' S, 139 ° 48 ' E, 370–400 m, 24 Oct. 1981; NMV A 21604View Materials (8 specimens), 268 mm TL, juvenile male; 300 mm TL, adolescent male; 328 mm TL, adolescent male; 328 mm TL, mature male; 343 mm TL, mature male; 173 mm TL, female; 334 mm TL, female; 347 mm TL, female, off Portland, South Australia, 38 ° 25 ' S, 140 ° 47 ' E, 252–378 m, 17 Jun. 2000; NMV A 21605View Materials (2 specimens), 128 mm TL, juvenile male; 153 mm TL, juvenile male, off Portland, South Australia, 38 ° 24 ' S, 140 ° 41 ' E, 207–360 m, 18 Jun. 2000; NMV A 21606View Materials (2 specimens), 151 mm TL, juvenile male; 258 mm TL, female; NMV A 21608View Materials, 190 mm TL, female, off Portland, Victoria, 38 ° 42 ' S, 141 ° 20 ' E, 225–374 m, 10 Jun. 2000.
Diagnosis. A species of Pavoraja with: a relatively long, oval tail, length 57–58 % TL, height at pelvic-fin tips about three-quarters of width, width at midlength 1.4–1.9 % TL; small orbits, diameter 4.0– 4.8 % TL; widely spaced gill slits, width between first gill openings 11.1–13.3 % TL; relatively narrow interorbital space, width 2.7–3.1 % TL; broad nasal curtain, total width 6.1–7.3 % TL; orbital thorns large, mostly 2 on posteromedial margin; interorbital, spiracular and scapular thorns absent; nuchal pore patch prominent, usually preceded by a nuchal thorn; thorns of tail series large, not strongly decreasing in size posteriorly; interdorsal space relatively long, generally subequal to first dorsal-fin base; epichordal lobe of caudal fin not confluent with second dorsal fin, base of lobe equal to in length or longer than dorsal-fin bases; tooth rows in lower jaw 31–43; predorsal caudal centra 65–72; interdorsal vertebrae 9–13; pectoral radials 73–77; pale yellowish brown, sometimes with faint dusky blotches, lacking a pattern of white spots in adults; dorsal fins usually pale centrally with dusky outer margins; epichordal lobe usually dusky, not strongly demarcated from dorsal fins; ventral surface mainly whitish with broad greyish areas on corners of disc and posterior lobes of pelvic fins.
Description. Disc 1.13 in holotype (1.06–1.13 in paratypes) times as broad as long; maximum angle in front of spiracles 108 ° (100–108 °); anterior margin convex with a deep concavity near its midlength in males and females (less so in juveniles and some females); posterior margin strongly convex; outer corners broadly rounded. Snout width at axis through anterior border of orbits 75 % (67–76 % in female paratypes) of distance from tip of snout to axil of pectoral fins. Pelvic-fin anterior margin 86 % (73–96 %) of distance from origin of anterior lobe to posterior extremity of fin. Tail length 1.20 (1.16–1.30) times disc length; widths at midlength and at axils of pelvic fins 40 % (32–41 %) and 110 % (91–111 %) of orbit diameter respectively; skin fold very narrow anteriorly, extending along ventrolateral surface from near or slightly forward of pelvic-fin tip to near origin of hypochordal lobe of caudal fin, widest beneath second dorsal fin (subequal to height of epichordal lobe of caudal fin). Interdorsal distance relatively long, generally subequal to length of first dorsal-fin base; epichordal caudal fin not connected to base of second dorsal fin, base equal to or slightly longer than bases of dorsal fins.
Preocular length 3.00 (2.24–3.08) times longer than orbit diameter; preoral length 2.78 (1.94–2.47) times internarial distance. Orbit diameter 1.39 (1.47–1.63) times interorbital distance; 1.55 (1.69–2.04) times length of spiracles. Internarial distance 0.37 (0.36–0.43) in distance between first gill slits; 0.63 (0.54–0.78) in distance between fifth gill slits. Length of first gill slit 1.76 (1.03–1.38) times length of fifth gill slit; 0.24 (0.13– 0.18) in mouth width.
Dorsal surfaces of disc densely covered with fine denticles; pelvic-fin anterior and posterior lobes, claspers, caudal-fin lobes, lateral skin fold, and entire ventral surface naked; denticles on posterior half of tail sparse; much denser band of slightly enlarged, pungent denticles extending along midline of disc from nuchal area to anterior third of tail (its width subequal to orbit diameter), most pronounced in largest individuals; dorsal fins with weak granulations. Orbit with 0–3 (mostly 2 in large individuals, absent in juveniles <108 mm TL) thorns on anteromedial margin, 1–3 (mostly 2 in large individuals, absent in juveniles <108 mm TL) on posteromedial margin, absent on medial margin; interorbital thorns absent; one interspiracular thorn sometimes present. Scapular thorns absent. Prenuchal and nuchal thorns 0–5 (mostly 2 or 3 in large individuals, absent in juveniles <220 mm TL), anteriormost thorn (sometimes feeble or damaged) situated forward of nuchal pore patch. Tail with rather large, widely spaced thorns arranged in 3 series, thorns not decreasing strongly in size posteriorly; medial series originating near level of pectoral-fin insertion (further forward in NMV A 21604View Materials, female 334 mm TL), generally persisting to origin of first dorsal fin; dorsolateral series originating over pelvic-fin inner margin, extending along more than two-thirds to three quarters length of tail in large individuals; inter-dorsal thorns absent. Adult males with 2–3 rows of small, weak, non-retractable alar thorns; malar thorn patch small; malar thorns similar in form to alar thorns, much smaller, situated anterolaterally, extending anteriorly to just in advance of level of pored prenuchal area. Smallest juvenile ( NMV A 21605View Materials) without orbital and nuchal thorns; median row of tail thorns well developed, thorns much larger than tail denticles.
Claspers slender (Figs 6 d –f), pseudorhipidion extending posteriorly to distal quarter of glans as fold of integument that finally becomes fused with glans floor; spur passing proximally under slit, distal tip lying near glans margin; rhipidion well developed, extending over central third of glans, distal section lying over base of sentinel; sentinel large, well developed, rod-shaped to ovoid and covered by integument, extending from level of slit to past tip of glans; spike just visible within well-defined sentina; axial cartilage curved laterally, slen- der; dorsal marginal not expanded distally, pseudorhipidion expanded distally to form a dorsal flag-like extension then thinning abruptly to a sharp point; ventral marginal with an evenly convex distal margin; dorsal terminal 1 and ventral terminal very narrowly joined on ventral aspect of glans, forming sheath-like covering extending over central half of glans; dorsal terminal 1 very membranous; ventral terminal very membranous, with thickened area immediately distal to proximal arm, arm penetrating glans and lying against dorsal margin of proximal extension of accessory terminal 1; terminal bridge absent or incomplete; lateral margin of dorsal terminal 2 distinctly angular, not serrated; dorsal terminal 3 small to moderately large; accessory terminal 1 with bow-shaped distal extension forming sentinel, extending to level of dorsal terminal 3.
Neurocranium of CSIRO H 174 –01 typical of genus; with one accessory lateral cartilage on the side of the right rostral appendix; foramina absent from rostral node; rostral shaft short, much less than length of basal fenestra; posterior fontanelle longer than anterior fontanelle.
Scapulocoracoid with 3 postventral foramina, posterior foramen sometimes largest.
Meristics (n= 17). Tooth rows in upper jaw 34 (33–42), in lower jaw 34 (31–43). Vertebral counts: monospondylous centra 27 (26–29), predorsal caudal centra 68 (65–72), interdorsal centra 13 (9–13), diplospondylous centra 112 (106–113), total centra 139 (134–141). Pectoral-fin counts: propterygial radials 33 (33–35), mesopterygial radials 14 (13–16), metapterygial radials 27 (25–28), total radials 74 (73–77). Pelvic-fin counts: males 3 (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, often with dusky blotches; disc and pelvic-fin margins slightly paler than rest of body; anterior lobes of pelvic fins white, strongly demarcated from posterior lobes; median region of snout paler than body, often with a dusky stripe along its midline; pored prenuchal area large, prominent, appearing as a diffuse-edged white, subcircular to suboval blotch; lateral skin fold white or lightly pigmented anteriorly, dusky beneath dorsal fins; ocular membrane semi-translucent, pale brownish; fleshy process on snout usually pigmented. Claspers uniformly greyish brown dorsally with pale lateral margins; posterolateral and posteromesial margins of glans white; white ventrally. Dorsal fins predominantly dusky, central section paler, outer posterior membrane translucent. Epichordal lobe of caudal fin generally uniformly dusky. Ventral surface mostly white, usually with greyish outer corners on disc, posterior lobes of pelvic fins and near apex of tail. Smallest juveniles yellowish brown on disc, usually with large dusky blotches; sparse coverage of white spots sometimes on disc in specimens <220 mm TL; two rows of fine white spots extending from mid disc onto dorsolateral tail in some juveniles; tail colour similar to disc; dorsal fins much darker than rest of body, darker transverse bands indistinct; ventral surface white to semi-translucent centrally, outer margins of pectoral fins and posterior lobes of pelvic fins dark greyish brown.
Size. At least 343 mm TL and about 180 mm disc width. Smallest mature male 288 mm TL ( CSIRO H 173 –01), but some males adolescent at 300–330 mm TL. Smallest post-natal juvenile 128 mm TL.
Distribution. Known from the Great Australian Bight off southern Australia, between south of Cape Leeuwin, Western Australia (34 ° 59 ' S, 114 ° 53 ' E), and off Portland, Victoria (38 ° 42 ' S, 141 ° 20 ' E), in depths of 192–712 m (types mainly from 300–400 m).
Holotype Non-types Holotype Paratypes
Min. Max. Mean Min. Max. Mean
Total length (mm) 297 216 349 272 257 332 Etymology. From the Latin arenarius (sandy) in allusion to its pale dorsal disc coloration.
Comparisons. Close to P. alleni in morphology and with a similar colour pattern, being uniform pale yellowish brown, with or without faint dusky blotches, and lacking white spots in adults. The pored prenuchal area, which is evident as a large white spot in P. arenaria , is much more prominent than in P. a l l e n i. The two species differ in some morphometric and meristic characters. Pavoraja arenaria has fewer predorsal caudal centra (65–72 vs. 73–79) and more pectoral-fin radials (73–77 vs. 64–66) than P. a l l e n i, generally larger thorns on the tail, and scapular thorns are absent (rather than sometimes present). The dorsal surface of the tail near the first dorsal-fin origin in P. arenaria usually has a few large thorns but is otherwise almost naked (surface hirsute, covered instead with a carpet of minute denticles and mostly without large thorns in P. a l l e n i). White spots, which are present in clusters in all sizes of P. n i t i d a, are present on the posterior disc of some juvenile P. arenaria .
Remarks. P. arenaria belongs to the Southern marine biogeographic province of Australia ( IMCRA 1998) where it is primarily found in the upper slope biome ( Last et al., 2005).
|Distance-cloaca to second dorsal-fin origin||44.3 51.0|
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