Pavoraja alleni McEachran and Fechhelm

Last, Peter R. & Yearsley, Stephen Mallick And Gordon K., 2008, A review of the Australian skate genus Pavoraja Whitley (Rajiformes: Arhynchobatidae), Zootaxa 1812, pp. 1-45 : 5-13

Pavoraja alleni McEachran and Fechhelm

( Figs 1 a, 2a, 3–5, 6a–c, Tables 1 , 4 )

Pavoraja alleni McEachran and Fechhelm, 1982: 8 –11, figs 1, 2, 4, 5, 7, 8 (orig. descr.; northwestern Australia).

Holotype. WAM P 19118–001, 297 mm TL, adult male, near Rowley Shoals, Western Australia, 17°17' S, 119°57' E, 350 m, 20 Dec. 1969.

Other material. 33 specimens (112–349 mm TL). AMS I 23423–006 (3 specimens), 258 mm TL, juvenile male; 317 mm TL, adult male; 339 mm TL, female, northern Western Australia, 18°01' S, 118°23' E, 376 m, 1 Aug. 1982; CSIRO CA 2833, 216 mm TL, juvenile male, south-west of Imperieuse Reef, Western Australia 17°48' S, 118°30' E, 404 m, 3 Apr. 1982; CSIRO CA 3926, 281 mm TL, adolescent male; CSIRO CA 3927, 283 mm TL, female; CSIRO CA 3928, 270 mm TL, female; CSIRO CA 3929, 292 mm TL, adult male, south of Imperieuse Reef, Western Australia, 17°40' S, 119°01' E, 318–360 m, 6 Feb. 1983; CSIRO CA 4332, 294 mm TL, adult male, north of Imperieuse Reef, Western Australia, 18°03' S, 118°13' E, 418–420 m, 5 Feb. 1983; CSIRO CA 4345, 298 mm TL, female; CSIRO CA 4346, 269 mm TL, female; CSIRO CA 4348, 295 mm TL, female, north of Dampier Archipelago, Western Australia; 18°54' S, 116°11' E, 402–404 m, 30 Jan. 1984; CSIRO CA 4357, 320 mm TL, female, south-west of Imperieuse Reef, Western Australia, 18°01' S, 118°15' E, 396–412 m, 28 Jan. 1984; CSIRO CA 4360, 315 mm TL, adolescent male, off Port Hedland, Western Australia, 18°34' S, 117°35' E, 356–358 m, 1 Feb. 1984; CSIRO CA 4366, 297 mm TL, female; CSIRO CA 4369, 305 mm TL, adult male, south-east of Mermaid Reef, Western Australia; 17°17' S, 120°12' E, 304– 305 m, 4 Feb. 1984; CSIRO CA 4374, 167 mm TL, female, north-west of Dampier Archipelago, Western Australia, 18°53' S, 116°10' E, 456–458 m, 30 Jan. 1984; CSIRO CA 4376, 337 mm TL, female, CSIRO CA 4378, 349 mm TL, female, CSIRO CA 4379, 289 mm TL, adult male, north of Legendre Island, Western Australia, 18°46' S, 117°08' E, 350–354 m, 31 Jan. 1984; CSIRO CA 4392, 297 mm TL, adult male, north-east of Monte Bello Islands, Western Australia, 19°19' S, 115°45' E, 306–308 m, 29 Jan. 1984; CSIRO CA 4398, 220 mm TL, female; CSIRO CA 4399, 242 mm TL, female; CSIRO CA 4400, 227 mm TL, female; near Imperieuse Reef, Western Australia; 17°58' S, 118°22' E, 406–416 m, 28 Jan. 1984; CSIRO CA 4404, 255 mm TL, juvenile male, south-east of Scott Reef, west of Bonaparte Archipelago, Western Australia, 14°10' S, 122°35' E, 348–350 m, 14 Feb. 1984; CSIRO CA 4412, 317 mm TL, female; CSIRO CA 4415, 331 mm TL, female; CSIRO CA 4417, 332 mm TL, female; near Monte Bello Islands, Western Australia, 19°20' S, 115°41' E, 348–352 m, 29 Jan. 1984; CSIRO T 1356, 217 mm TL, female; CSIRO T 1357, 150 mm TL, female; CSIRO T 1358, 158 mm TL, female; CSIRO T 1359, 256 mm TL, juvenile male; south of Imperieuse Reef, Western Australia, 17°40' S, 119°01' E, 318–360 m, 6 Feb. 1983; CSIRO H 1637–01 (smallest of 5 specimens), 112 mm TL, female, south-west of Rowley Shoals, Western Australia, 17°39' S, 118°40' E, 410 m, 22 Aug. 1988; CSIRO H 6583–01, 100 mm TL, female, off Nickol Bay, Western Australia 18°46' S, 116°54' E, 400––404 m, 13 Jun. 2007.

Diagnosis. A species of Pavoraja with: a relatively long, narrow tail, length 55–59% TL, width at midlength 1.1–2.0% TL; small orbits, diameter 3.8–5.2% TL; widely spaced gill slits, width between first fill openings 11.8–13.8% TL; broad interorbital space, width 2.7–4.0% TL; broad nasal curtain, total width 6.2– 8.2% TL; orbital thorns large, mostly 2 or 3 on posteromedial margin; interorbital, spiracular and scapular thorns sometimes present; nuchal pore patch small or barely detectable, rarely preceded by a nuchal thorn; thorns of tail series smaller, less dense near first dorsal fin than those anteriorly; interdorsal space relatively long, generally subequal to or shorter than first dorsal-fin base; epichordal lobe of caudal fin not confluent with second dorsal fin, base of lobe subequal to dorsal-fin bases; tooth rows in lower jaw 32–40; predorsal caudal centra 73–79; interdorsal vertebrae 9–12; pectoral radials 64–66; pale yellowish brown, often with faint dusky blotches, lacking pattern of white spots; dorsal fins usually greyish centrally with paler outer margins; epichordal lobe usually dusky, not strongly demarcated from dorsal fins; ventral surface almost uniformly whitish, outer corners of disc not conspicuously darker.

B, P. a ren ar ia sp. nov., paratype CSIRO H 173–01, 288 mm TL;

C, P. m o s a i c a sp. nov., holotype CSIRO H 643–02, 274 mm TL;

D, P. nitida , CSIRO H 135–01, 342 mm TL;

E, P. pseudonitida sp. nov., holotype CSIRO H 438–01, 372 mm TL; F, P. umbrosa sp. nov., paratype CSIRO T 1363–01, 369 mm TL.

cf–cleft, hy–hypopyle, pr–pseudorhipidion, rh–rhipidion, sl–slit, sp–spike, sr–spur, st–sentinel.

B, P. a ren ar ia sp. nov., paratype CSIRO H 174–01, female 307 mm TL; C, P. m o s a i c a sp. nov., paratype CSIRO H 652–01, female 279 mm TL; D, P. nitida , CSIRO H 138–01, female 335 mm TL;

E, P. pseudonitida sp. nov., paratype CSIRO H 442–01, female 344 mm TL; F, P. umbrosa sp. nov., paratype CSIRO T 1364–01, female 309 mm TL. af–anterior fontanelle, msc–mesocondyle, mtc–metacondyle, pdfe–postdorsal fenestra, prc–procondyle, pvf–postventral foramina, scp–scapular process.

Description. Disc 1.05–1.17 times as broad as long; maximum angle in front of spiracles 94–102°; snout angular or broadly rounded in adult males; anterior margin weakly convex or straight in females and immature males, mostly deeply double convex in adult males (deeply concave besides spiracles); posterior margin strongly convex; outer corners broadly rounded. Snout width at axis through anterior border of orbits 59–65% in mature males, 69–82% in females of distance from tip of snout to axil of pectoral fins. Pelvic-fin anterior margin 59–98% of distance from origin of anterior lobe to posterior extremity of fin. Tail length 1.13–1.40 times disc length; widths at midlength and at axils of pelvic fins 27–50% and 67–115% of orbit diameter respectively; skin fold extremely narrow anteriorly, extending along ventrolateral surface from over or slightly behind pelvic-fin tip to near origin of hypochordal lobe of caudal fin, widening markedly over dorsal fins (subequal to height of epichordal lobe of caudal fin). Interdorsal distance long, variable, generally subequal to or shorter than first dorsal-fin base; epichordal caudal-fin lobe not connected to base of second dorsal fin, base subequal to bases of dorsal fins; female CSIRO CA 4400 with a single dorsal fin.

Preocular length 2.00–3.25 times longer than orbit diameter; preoral length 2.06–2.92 times internarial distance. Orbit diameter 1.11–1.53 times interorbital distance; 1.43–2.20 times length of spiracles. Internarial distance 0.36–0.45 in distance between first gill slits; 0.56–0.81 in distance between fifth gill slits. Length of first gill slit 0.80–1.59 times length of fifth gill slit; 0.11–0.26 in mouth width.

Dorsal surfaces of disc, tail and posterior lobes of pelvic fins densely covered with fine denticles; dorsal fins and epichordal lobe lightly denticulate or naked. Claspers, anterior lobes of pelvic fins, skin folds on tail, and entire ventral surface naked. Orbit of adult individuals with 1–4 (mostly 2 or 3) thorns on anteromedial margin, 1–5 (mostly 2 or 3) on posteromedial margin, 0–1 (rarely 1) on medial margin; adults occasionally with a pair of interspiracular thorns and a single interorbital thorn. Prenuchal and nuchal thorns 1–6 (mostly 3 or 4), prominent, mostly situated posterior to pale, pored prenuchal area (first rarely in advance of pored area); single transverse row of thorns across scapulocoracoid in some adults (both males and females). Three series of moderately large, closely set, thorns on tail (single linear row in juveniles, dorsolateral rows emergent at about 250 mm TL); thorns minute, absent or sparse in all rows for about a snout length forward of first dorsal fin; tail rows extending variably onto disc to about its midlength (less persistent in smaller individuals); medial series regular, prominent, originating near level of pectoral-fin insertion; interdorsal thorns rarely present; dorsolateral series usually penetrating further anteriorly than median series. Alar thorns small, nonretractable, in 1–3 (rarely 4–5) irregular rows, not developed into dense patch of irregularly shaped thorns; malar thorns slightly smaller; malar thorn patch small, merging with alar thorns near anterolateral margin of disc, extending anteriorly to about level with nuchal pore patch; sometimes with a small isolated patch of minute thorns on lateral disc margin at anterior border of orbits. Smallest juveniles without disc thorns; tail with a single median row of thorns; tail thorns much larger than adjacent denticles; midline of tail adjacent thorns naked.

FIGURE 6. Right clasper cartilages of Pavoraja alleni , CSIRO CA 4332, adult male 294 mm TL: A, Lateral view, partially expanded with dorsal and ventral terminal cartilages shown separately; B, Dorsal view; C, Ventral view. Right clasper cartilages of P. a re n a r i a sp. nov., paratype CSIRO H 173–01, 288 mm TL; D, Lateral view, partially expanded with dorsal and ventral terminal cartilages shown separately; E, Dorsal view; F, Ventral view. atr1–accessory terminal 1, atr2–accessory terminal 2, ax–axial, dmg–dorsal marginal, dtr1–dorsal terminal 1, dtr2–dorsal terminal 2, dtr3–dorsal terminal 3, tb–terminal bridge, vmg–ventral marginal, vtr–ventral terminal.

Claspers very slender (Figs 6a–c); inner dorsal lobe continuing distally under sentinel to distal one-quarter of glans as fold of integument; spur passing under slit proximally, the distal tip either lying on or slightly outside glans margin; rhipidion poorly to well developed, running from proximal one-third to distal one-third of glans, distal section lying over base of sentinel; sentinel shape variable, generally rod-shaped and extending to near glans margin, occasionally curved laterally and extending past glans tip; spike visible within sentina; axial cartilage curved laterally, slender; dorsal marginal little expanded distally, inner extension of distal margin initially expanded to a blade-like edge and then gradually thinning to a point; ventral marginal with truncated distal margin (joint unclear); dorsal terminal 1 and ventral terminal narrowly joined on ventral aspect of glans, forming sheath-like covering over central half of glans; dorsal terminal 1 membranous; ventral terminal mostly membranous, with thickened area immediately distal to proximal arm; arm just penetrating glans to lie against dorsal margin of proximal extension of accessory terminal 1; dorsal terminal 2 with poorly defined cartilaginous projection joined to axial near level of accessory terminal 2 base by connective tissue (incomplete terminal bridge), lateral margin not jagged or serrated; dorsal terminal 3 moderately large; accessory terminal 1 with a laterally curved or S-shaped distal extension forming sentinel, extending to near axial tip.

Neurocranium of CSIRO CA 4417 typical of genus; with one accessory lateral cartilage on each side of rostral appendices; 2 foramina on rostral node; rostral shaft subequal to length of basal fenestra; posterior fontanelle relatively short.

Scapulocoracoid mostly with 3 postventral foramina (middle smallest when present), otherwise with 2 large foramina; additional condyle sometimes present on neopterygial ridge.

Meristics (n=11). Tooth rows in upper jaw 38 (33–40), in lower jaw 37 (32–40). Vertebral counts: monospondylous centra 25 (25–26), predorsal caudal centra 77 (73–79), interdorsal centra 10 (9–12), diplospondylous centra 112 (106–115), total centra 137 (131–141). Pectoral-fin counts: propterygial radials 29 (29–32), mesopterygial radials 12 (9–12), metapterygial radials 24 (22–26), total radials 65 (64–66). Pelvic-fin counts: males 3 (3–4) + 15 (15–17) radials, females 3–4 + 15–18 radials.

Coloration. Preserved and live colour similar. Dorsal surfaces of disc, tail, claspers and posterior pelvicfin lobes yellowish to pale brown; disc scattered with large, slightly darker, diffuse-edged, dark brown blotches; dark narrow bands evident on tail; blotches most prominent in immatures, almost undetectable in some adults; dark brown triangular patch usually present on scapular arch, just posterior to pale pored nuchal area; pale nuchal area small, often barely detectable; mid snout region pale, bordered laterally by darker diagonal stripes that follow propterygia; outer area of disc and posterior lobes of pelvic fins paler than central regions; anterior lobes of pelvic fins white; orbital membrane semi-translucent, lightly pigmented. Dorsal fins dusky grey centrally, generally with pale or translucent outer margins, fin bases sometimes pale. Epichordal lobe usually dusky, not strongly demarcated from dorsal fins. Ventral surface almost uniformly whitish; outer corners of disc not conspicuously darker. Juvenile (e.g. CSIRO H 6583–01, 100 mm TL) pale yellowish with fine dark spots and larger dusky blotches on dorsal surface of disc; about 4 dark bands on anterior and middle of tail; prominent dark bars on and below dorsal fins and on postdorsal tail; translucent ventrally. Specimens about 150 mm TL and larger have adult dorsal coloration.

Size. At least 349 mm TL and about 176 mm disc width; males usually mature by 289 mm TL but one specimen (CSIRO CA 4360) was adolescent at 315 mm TL. Smallest post-natal specimen (CSIRO H 1637– 01) was 112 mm TL.

Distribution. Distributed along the upper continental slope off Western Australia, between north-east of the Monte Bello Islands (19°21' S, 115°42' E) and the Bonaparte Archipelago (14°11' S, 122°35' E), in depths of 304– 458 m.

Comparisons. This northwestern Australian species differs from an allopatric southern species, P. nitida , in coloration morphometrics and meristics. Our material of P. alleni has more predorsal caudal centra 73–79 (62–70), marginally more interdorsal centra 9–12 (8–10), and fewer pectoral radials 64–66 (70–74). It also has a longer and narrower tail (length 55–59% vs. 52–57% TL), slightly smaller orbits (diameter 3.8–5.2% vs. 4.5–5.7% TL), and smaller tail thorns. The epichordal lobe of the caudal fin of P. alleni is not confluent with the second dorsal fin (rather than mostly confluent), and the base of this lobe is longer than the dorsal-fin bases (equal in length or shorter). Also the dorsal disc is pale yellowish brown (often with faint dusky blotches) but never has clusters of white spots typical of P. nitida . Differences between P. alleni and four other new species of Pavoraja are discussed in the following sections.

Our material conforms well to the 3 types as described by McEachran and Fechhelm (1982). A paratype is recorded as having 28 monospondylous vertebrae (26 in both other types and 25–26 in our material, n=11) and 71 predorsal caudal centra (74, 79 in the other types and 73–79 in our material). Also, the pectoral radial counts were 63, 67 (vs. 64–66). A few minor differences in morphometrics are probably due to the use of slightly different methodology.

The young of Leucoraja sp. O (as Raja sp. O sensu Last and Stevens, 1994), which resemble young P. alleni in body shape, colour, and the size and position of thorns, have been misidentified as that species. However, they can be distinguished by the presence of a firm rostral cartilage (evident when the head of the specimen is backlit) in Leucoraja sp. O that is lacking in members of the genus Pavoraja .

Remarks. Pavoraja alleni belongs to the North Western and Timor marine biogeographic provinces of Australia where it is primarily found in the upper slope biome ( Last et al., 2005). Additional material collected recently from the continental slope off southwestern Australia, from Shark Bay (24°42' S) southwards to Mandurah (32°40' S) at 360–760 m depth, was initially identified as P. alleni but seems to be another undescribed species. This allopatric morph, which differs slightly in morphometrics to the typical form of P. a l l e n i, has a dusky ventral surface (rather than pale) and more strongly developed tail thorns. More research is required to establish its status.

Figures

FIGURE 1. Lateral view of right clasper, partially expanded to show components: A, Pavoraja alleni, CSIRO CA 3929, 292 mm TL;