Pavoraja nitida (Günther), Gunther

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 : 24-30

Pavoraja nitida (Günther)

( Figs 1 d, 2d, 13d–f, 14–16, Tables 2 , 4 )

Raja nitida Günther, 1880 (orig. descr.; Twofold Bay, New South Wales). Pavoraja nitida . Whitley, 1939 (n. comb.).

Pavoraja (Pavoraja) nitida . McEachran, 1984 (n. comb.).

Holotype. BMNH 1879.5.14.417, 210 mm TL, immature male, off Twofold Bay, New South Wales, ca 220 m.

Other material. 26 specimens (80–368 mm TL): CSIRO A 2956, 203 mm TL, juvenile male, possibly Port Hacking, New South Wales; CSIRO CA 39, 343 mm TL, adult male, off Lakes Entrance, Victoria, 38°27' S, 148°33' E, 250–390 m, 28 Nov. 1976; CSIRO CA 130, 358 mm TL, adult male, south-east of Conran Point, Victoria, 38°05' S, 148°51' E, 120–125 m, 28 Apr. 1977; CSIRO CA 511, 315 mm TL, adult male, east of South Bruny Island, Tasmania, 43°30' S, 147°32' E, 9 Nov. 1978; CSIRO CA 520, 304 mm TL, adolescent male, off Ulladulla, New South Wales, 35°29' S, 150°45' E, 200–204 m, 20 Oct. 1978; CSIRO CA 522, 326 mm TL, adult male, south of Red Rocks Point, Western Australia, 32°24' S, 127°30' E, 30 m, 3 Mar. 1978; CSIRO CA 523, 293 mm TL, adolescent male, north-east of Maria Island, Tasmania, 42°31' S, 148°19' E, 100 m, 7 Nov. 1978; CSIRO CA 2817, 333 mm TL, adult male; CSIRO CA 2818, 337 mm TL, female, off Gabo Is., Victoria, 37°45' S, 150°11' E, 180–200 m, 2 Feb. 1980; CSIRO H 134–01, 342 mm TL female; CSIRO H 135–01, 341 mm TL, adult male; CSIRO H 136–01, 335 mm TL, adolescent male; off south-west Tasmania, Dec. 1981; CSIRO H 137–01, 288 mm TL, adult male, off south-east Tasmania, 110 m, May 1978; CSIRO H 138–01, 335 mm TL, female, off Norah Head, New South Wales, 33°27' S, 152°05' E, 360–432 m, 21 Aug. 1979; CSIRO H 139–01, 316 mm TL, adult male, off Barrenjoey Head, New South Wales, 33°42' S, 151°51' E, 296–300 m, 25 Jan. 1982; CSIRO H 140–01, 345 mm TL, female; CSIRO H 141–01, 326 mm TL, female; off south-east Tasmania, 75 m, Sep. 1981; CSIRO H 142–01, 305 mm TL, female; CSIRO H 143–01, 307 mm TL, adult male; off south-east Tasmania, 110 m, May 1978; CSIRO H 144–01, 320 mm TL, female, Taupo Seamount, off Port Hacking, New South Wales, 34°17' S, 151°21' E, 200 m, 25 Mar. 1981; CSIRO H 145–01, 282 mm TL, adolescent male; CSIRO H 146–01, 286 mm TL, juvenile male; off south-east Tasmania, 75 m; CSIRO H 1264–08, 335 mm TL, female, off Maria Island, Tasmania, 42°35' S, 148°12' E, 81–82 m, 7 Apr. 1988; CSIRO H 3524–03, female, 368 mm TL, south of Cape Everard, Victoria, 38°11' S, 149°15' E, 158–180 m, 8 Aug. 1993; CSIRO H 3526–01, 103 mm TL, juvenile male, off Cape Everard, Victoria, 38°10' S, 149°35' E, 263–266 m, 9 Aug. 1993; CSIRO T 1049, 80 mm TL, female, Tasmania.

Diagnosis. A species of Pavoraja with: a relatively short, broad tail, length 52–57% TL, width at midlength 2.0–2.5% TL; large orbits, diameter 4.5–5.7% TL; widely spaced gill slits, width between first fill openings 11.7–14.1% TL; broad internasal space, width 3.8–4.9% TL; tall dorsal fins, first dorsal-fin height 2.6–3.4% TL; orbital thorns large, mostly 3 on posteromedial margin; interorbital thorns absent; spiracular thorns generally present in adults; scapular thorns sometimes present; thorns of tail series large, decreasing in size posteriorly, often absent immediately before first dorsal fin; interdorsal space short or fins connected; epichordal lobe of caudal fin mostly confluent with second dorsal fin, base of lobe equal in length to or shorter than dorsal-fin bases; tooth rows in lower jaw 31–36; predorsal caudal centra 62–70; interdorsal vertebrae 8– 10; pectoral radials 70–74; upper surface of disc brownish with regular, pale spots arranged into irregular clusters.

Description. Disc 1.10–1.17 times as broad as long; maximum angle in front of spiracles 97–108°; anterior margin convex to weakly concave in females and immature males, mostly deeply concave opposite spiracles in males (some adult males intermediate between extreme male condition and female condition); posterior margin strongly convex; outer corners broadly rounded. Snout width at axis through anterior border of orbits 58–59% in mature males, 69–73% in females of distance from tip of snout to axil of pectoral fins. Pelvic-fin anterior margin 62–75% of distance from origin of anterior lobe to posterior extremity of fin. Tail length 0.98–1.20 times disc length; widths at midlength and at axils of pelvic fins 38–50% and 88–106% of orbit diameter respectively; narrow skin fold extending along ventrolateral surface from just forward of pelvic-fin tip to near origin of hypochordal lobe of caudal fin (when undamaged), widest beneath second dorsal fin (subequal to height of epichordal lobe of caudal fin). Interdorsal distance very short or fins often connected, always less than half length of first dorsal-fin base; epichordal caudal-fin lobe mostly connected to base of second dorsal fin, base equal to or slightly shorter than bases of dorsal fins.

Preocular length 1.75–2.40 times longer than orbit diameter; preoral length 2.14–3.21 times internarial distance. Orbit diameter 1.45–1.78 times interorbital distance; 1.45–1.80 times length of spiracles. Internarial distance 0.30–0.39 in distance between first gill slits; 0.52–0.79 in distance between fifth gill slits. Length of first gill slit 1.00–1.33 times length of fifth gill slit; 0.18–0.30 in mouth width.

Dorsal surfaces of disc, tail and anterior lobes of pelvic fins densely covered with fine denticles. Dorsal fins lightly denticulate to almost naked. Claspers, posterior lobes of pelvic fins, skin folds on tail, caudal lobes and entire ventral surface naked. Orbit with 2–5 (mostly 3) thorns on anteromedial margin, 2–4 (mostly 3) on posteromedial margin, 0–1 (rarely present) on medial margin; adults generally with single prominent thorn either side of midline between posterior margins of spiracles. Prenuchal and nuchal thorns small, 1–5 (mostly 2 or 3), sometimes with a few smaller thorns around primary thorns, on scapular region and extending as multiple rows down midline of disc. Tail with 3–5 series of thorns, forming a dense patch above cloaca; dorsolateral series highly irregular, staggered near base of tail, each series often extending anteriorly onto disc to join with rows on midline, usually absent or weakly developed just forward of first dorsal-fin origin; median series more regular, extending along full length of tail, seldom extending onto disc; interdorsal thorns rarely present. Adult males with a dense patch of 1–4 regular to irregular rows of small non-retractable alar thorns (often as paired thorns); malar thorns smaller, situated anterolaterally and almost connected to alar thorn patch, extending anteriorly to greatest concavity of anterior margin of disc (usually just behind axis through posterior borders of spiracles). Juvenile (CSIRO A 2956) with 2 enlarged anteromedial orbital thorns, 1–2 main enlarged posteromedial orbital thorns; single enlarged nuchal thorn; tail with 3 distinct rows of thorns, median row best developed; smallest juvenile male (CSIRO H 3526–01) with a single preorbital thorn and single median row of tail thorns.

Claspers slender ( Figs 13 d–f); pseudorhipidion continuing distally as fold of integument, finally becoming fused to glans floor; spur passing proximally under slit, distal tip either lying on or slightly outside glans margin; rhipidion well developed, extending over central third of glans, distal section lying over base of sentinel; sentinel rod-shaped, covered by integument which is thicker and more fleshy over lateral region, extending from level of slit to near tip of glans; spike located within sentina; axial cartilage slender; dorsal marginal slightly expanded distally; proximal three-quarters of pseudorhipidion rod-like, thinning distally to a point; ventral marginal with an expanded evenly convex distal margin (joint unclear); dorsal terminal 1 and ventral terminal joined ventrally, forming sheath-like covering over entire length of glans; dorsal terminal 1 membranous; ventral terminal V-shaped, mostly membranous, thickened area immediately distal to proximal arm, arm penetrating glans and lying against dorsal margin of proximal extension of accessory terminal 1; distal point of symphysis of dorsal terminal 1 and ventral terminal cartilages with small protrusion of thickened cartilage; dorsal terminal 2 with poorly defined cartilaginous projection joined to axial near level of accessory terminal 2 base by connective tissue (incomplete terminal bridge); dorsal terminal 3 moderately large; accessory terminal 1 with an S-shaped distal extension forming the sentinel, extending to distal margin of accessory terminal 2.

Neurocranium of CSIRO H 138–01 typical of genus; with no accessory lateral cartilages; 4 foramina on rostral node, anterior pair largest; rostral shaft very short, much less than length of basal fenestra; posterior fontanelle much longer than anterior fontanelle.

Scapulocoracoid with 2–4 postventral foramina, anterior foramen generally largest.

P. m o s a i c a sp. nov. P. nitida

Holotype Paratypes Holotype Non-types

Min. Max. Mean Min. Max. Mean

Total length (mm) 274 182 279 210 282 358 Meristics (n=7). Tooth rows in upper jaw 32–35, in lower jaw 31–36. Vertebral counts: monospondylous centra 26–30, predorsal caudal centra 62–70, interdorsal centra 8–10, diplospondylous centra 97–105, total centra 124–132. Pectoral-fin counts: propterygial radials 31–35, mesopterygial radials 12–14, metapterygial radials 25–27, total radials 70–74. Pelvic-fin counts: males 3–4 + 17–19 radials, females 3–4 + 19–21 radials.

Coloration. Preserved and live colour similar. Dorsal surface of disc, posterior lobes of pelvic fins and tail yellowish brown to dark brown with irregularly scattered paler and darker patches and blotches interspersed with poorly defined clusters of smaller and more distinct yellowish or white spots; clusters irregular in size with numerous small to minute, irregular shaped spots; mid area of snout and outer part of disc generally paler than central part of disc; anterior lobe of pelvic fin dusky with a pale margin; orbital membrane uniformly brown, paler along inner margin; nuchal pore patch small, whitish, suboval to elongate, prominent. Clasper uniformly dark brownish dorsally, with posterolateral margin of glans white tipped; uniformly white ventrally. Dorsal fins and epichordal lobe of caudal fin uniform pale brown, dusky or yellowish. Ventral surface mostly uniform white, occasionally with yellowish to greyish or translucent areas near outer corners of disc. Juvenile colour pattern different to adults; smallest male paratype CSIRO H 3526–01 pale yellowish dorsally with dense pattern of small lighter and darker spots and blotches; tail with evidence of weak darker bands, most prominent below dorsal fins; ventral surface pale translucent.

Size. To at least 368 mm TL. Smallest mature male 307 mm TL. Smallest postnatal juvenile 80 mm TL.

Distribution. Occurs on the continental shelf (and to a lesser extent the upper slope) of southeastern Australia, including Tasmania, north to at least off Norah Head, New South Wales (33°27' S, 152°05' E) and west to the central Great Australian Bight, Western Australia (32°24' S, 127°30' E), in depths of 75– 432 m.

Comparisons. Pavoraja nitida can be distinguished from plain-coloured or dark-blotched species, P. alleni and P. a re n a r i a (and P. sp. F sensu Last and Stevens, 1994; described later in this paper), by distinctive clusters of white spots on the dorsal surface. P. n i t i d a has 31–36 rows of teeth in the lower jaw and 62–70 predorsal caudal centra, fewer than other species with rich colour pattern, P. m o s a i c a and P. sp. E (sensu Last and Stevens, 1994; also described later in this paper), which have combined ranges for these characters of 37–47 tooth rows and 72–81 centra respectively. Also, P. m o s a i c a has a darker pattern (broken by irregular spots) than P. n i t i d a, whereas P. sp. E is more sparsely and evenly spotted than these species.

Whereas the vertebral counts of P. nitida in McEachran and Fechhelm (1982) closely matched those of this study (monospondylous centra 26–29 (holotype 27) n=16 vs. 26–30, n= 7 in our material; predorsal caudal centra 66–72 (holotype 66) vs. 62–70) some more extreme differences were detected in pectoral radial counts (62–73 (holotype 72) vs. 70–74). Our material generally conforms to McEachran and Fechhelm’s diagnosis of the species and morphometry of the holotype. However, two diagnostic characters, given as disc width greater than 54% TL (minimum of 53.1% in our material) and orbit diameter 1.7–2.1 (vs. 1.5–1.8) times spiracle length, differ slightly.

Remarks. P. n i t i d a belongs to the Central Eastern, Tasmanian, Southern, and Gulfs marine biogeographic provinces of Australia where it is found in the outer continental shelf and upper slope biome ( IMCRA, 1998; Last et al., 2005).

Figures

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

FIGURE 13. Right clasper cartilages of Pavoraja mosaica sp. nov., holotype CSIRO H 643 – 02, adult male 274 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. nitida, CSIRO H 135 – 01, 341 mm TL: D, Lateral view, partially expanded with dorsal and ventral terminal cartilages shown separately; E, Dorsal view; F, Ventral view. Abbreviations as in Fig. 6.

Tables

TABLE 2. Proportional measurements of holotypes with ranges and means of other material of Pavoraja mosaica sp. nov. (holotype CSIRO H 643 – 02; 6 paratypes) and P. nitida (holotype BMNH 1879.5. 14.417, from McEachran and Fechhelm, 1982; 10 non-types). Values are expressed as percentages of total length.

Disc width	58.0	54.9	58.2	56.8	59.0	53.1	58.2	55.7
Disc length	51.5	49.1	52.5	50.8	50.0	46.4	53.1	50.1
Snout length (preorbital)	13.1	12.8	13.6	13.2	11.0	9.1	12.2	10.8
Snout length (preoral)	15.0	13.9	15.4	14.7	11.8	9.8	13.4	11.6
Snout width (at anterior orbits)	25.8	30.5	33.5	32.1	–	22.1	31.3	26.8
Prenasal length	10.2	9.8	10.6	10.3	8.2	6.5	9.4	8.3
Orbit diameter	4.7	4.3	4.7	4.5	5.7	4.5	5.6	5.0
Interorbital width	2.9	2.9	3.4	3.1	3.2	2.7	3.6	3.1
Orbit and spiracle length	5.8	5.4	6.0	5.6	6.3	5.8	6.7	6.3
Spiracle length	2.6	2.2	3.0	2.5	3.2	2.8	3.4	3.0
Interspiracular width	6.6	6.4	7.3	6.8	6.5	6.5	7.2	6.9
Mouth width	7.6	0.0	7.8	6.2	6.3	6.0	7.2	6.7
Distance-nare to mouth	4.8	4.0	5.3	4.7	3.5	2.4	3.9	3.2
Internarial width	5.8	5.3	5.8	5.5	4.1	3.8	4.9	4.3
Width of first gill opening	1.1	0.9	1.4	1.2	1.7	1.2	1.8	1.4
Width of third gill opening	1.5	1.1	1.8	1.4	1.9	1.1	1.8	1.5
Width of fifth gill opening	1.1	0.9	1.3	1.1	1.6	1.0	1.5	1.3
Distance between first gill openings	12.4	13.2	14.1	13.4	13.0	11.7	14.1	12.9
Distance between fifth gill openings	6.9	6.6	7.7	7.4	7.0	5.8	8.9	6.9
Length of anterior pelvic-fin lobe	12.5	11.9	13.7	12.9	12.0	11.2	13.3	12.2
Length of posterior pelvic-fin lobe	17.9	15.6	17.7	16.9	16.0	16.2	18.5	17.7
Clasper length (post cloacal)	21.7	–	–	–	–	18.3	21.6	20.0
Tail width (at axil of pelvic fins)	4.4	3.8	4.3	4.2	–	4.3	5.4	4.8
Distance-snout to maximum width	30.3	26.7	29.9	28.7	29.0	25.4	28.5	27.0
Distance-snout to cloaca	46.7	47.0	49.1	47.8	44.0	43.6	47.5	44.9
Distance-snout to pectoral insertion	42.7	41.8	44.2	42.7	–	37.4	44.2	41.3
Distance-cloaca to first dorsal-fin origin	44.0	41.6	44.0	42.6	46.0	40.3	44.2	42.5
Distance-cloaca to caudal-fin origin	49.6	48.2	50.5	49.1	54.0	49.3	53.1	51.1
Distance-cloaca to second dorsal-fin origin	46.4	44.6	47.8	45.9	–	44.8	47.9	46.6
Distance-cloaca to caudal-fin tip	52.6	51.1	52.7	51.9	57.0	52.2	56.1	54.6
First dorsal-fin height	0.9	2.2	3.2	2.6	–	2.6	3.4	2.9
First dorsal-fin base length	1.8	2.2	3.9	3.2	–	3.5	4.5	4.1
Second dorsal-fin height	2.2	1.8	2.5	2.2	–	2.6	3.4	2.9
Second dorsal-fin base length	3.3	2.9	4.0	3.6	–	3.4	4.7	4.1
Tail height (at pelvic-fin tips)	1.8	1.4	1.9	1.7	–	1.8	2.7	2.3
Tail width (at pelvic-fin tips)	2.9	2.7	3.2	3.0	–	3.4	4.5	3.9
Tail width (at midlength)	1.8	1.6	1.9	1.7	–	2.0	2.5	2.3
Tail height (at first dorsal-fin origin)	0.7	0.7	1.1	0.8	–	0.9	1.2	1.0
Tail width (at first dorsal-fin origin)	1.1	1.1	1.3	1.1	–	1.2	2.4	1.8
Head length (to fifth gill opening)	27.4	25.3	26.9	26.4	–	21.8	25.7	24.4
Nasal curtain length	4.7	4.4	5.4	5.0	–	3.1	4.6	4.1
Nasal curtain (lobe width)	2.6	2.2	2.6	2.4	–	1.6	2.3	2.0
Nasal curtain (total width)	8.0	7.1	7.7	7.4	–	6.4	7.7	7.1