Orbiraja jensenae ( Last & Lim, 2010 )

Last, Peter R., Weigmann, Simon & Dumale, Don, 2016, A new skate genus Orbiraja (Rajiformes: Rajidae) from the Indo-West Pacific, Zootaxa 4184 (1) : -

Orbiraja jensenae ( Last & Lim, 2010)

( Figs 1–8 ; Table 1)

Okamejei jensenae Last & Lim, 2010 , 102–107, figs.

Material. PNM 10300 (formerly BRU 172 ), adult male 402 mm TL, Palapala , Cadiz City, Philippines, 6 Apr 2000.

Diagnosis (revised with inclusion of data from adult male). A small to medium-sized rostrorajin skate (to about 53 cm TL) with the following combination of characters: disc with narrowly to broadly rounded apices, width 59–71% TL, 1.1–1.2 times its length; snout angle 88–98°; tail relatively short in females (length 0.8–0.9 in distance from snout tip to rear of cloaca), longer in adult male (length 1.1 times distance from snout tip to rear of cloaca); tail width 1.5–1.8 times height at its midlength, 1.4–1.7 times at first dorsal-fin origin; pre-upper jaw length 17–18% TL, 2.0–2.2 times internasal width; ventral head length 29–32% TL; snout length 3.3–3.4 times interorbital width; orbit diameter 67–85% interorbital width; first dorsal-fin height 2.0– 2.7 in its base length; long procaudal length, distance from first dorsal-fin origin to tail tip 3.1–4.0 times first dorsal-fin base length, 3.2–6.3 times caudal-fin length; pelvic fins of medium size, length of posterior lobe 16–18% TL, length of anterior lobe 71–83% of posterior lobe; adult male lacking malar thorn patches; alar thorn patches small, broadly oval; adult clasper with greatly extended components spike and sentinel; accessory terminal 2 cartilage with strongly articulated medial distal extension, partly overlaying axial cartilage on median margin; anterior margins of both surfaces of disc of females with narrow denticle bands; single median series of thorns extending along entire midline of disc; tail thorns well developed, numerous, in 3 closely spaced median rows and irregular lateral row on each side (absent from dorsolateral region of tail); thorns in central median row fewer and smaller than in rows adjacent; total pectoral radials 80–82; trunk centra 26–31; predorsal centra 79–85; total centra 133–138; tooth rows in upper jaw 61–76; brownish and white spotted, with large dark pectoral spots bordered with smaller white spots when fresh; rostral cartilage demarcated from rest of snout; ventral surface whitish with outer margins of pectoral fins yellowish; ventral sensory pores minute, indistinct, not black-edged or surrounded by greyish blotches; dorsal fins dark anteriorly, paler posteriorly; caudal fin pale or brownish.

Remarks. The adult male has more narrowly rounded pectoral-fin apices than females of the type series, and the disc is proportionally narrower and the tail longer (see Table 1). Length measurements of the snout and head (i.e. preorbital length, prenasal length, pre-upper jaw length, and dorsal and ventral head lengths), as well as key width measurements of the head (i.e. interorbital, interspiracular, internasal, mouth and nasal curtain widths, and distances between the gill slits) are all smaller in the adult male than in females. The procaudal length in O. jensenae is long compared to most other rajin skates, and this value is greater in the adult male than in females (20.1% vs. 15.6–18.6% TL). Thorn patterns are similar between the sexes with the median tail thorns well developed and in 3 closely spaced rows, those in the middle row being sparser and distinctly smaller than those in the rows adjacent. The lateral thorns are similar in shape, more numerous, and extend along the edges of the tail and the dorsolateral region of tail is naked. In the adult male, the alar thorn patch is relatively small and oval in shape, and there are no malar thorn patches. Coloration appears consistent between the sexes.

Adult male Ranges for 5 female types

Total length (mm) 402.0 464.0 533.0 Disc width 59.0 64.7 70.6 Disc length (dir) 52.9 56.1 61.1 Snout to maximum width 30.9 30.7 33.6 Snout length (preorbital)—dir 14.7 15.6 17.2 Snout to spiracle 19.5 20.5 22.6 Head—dorsal 20.9 21.8 24.4 Orbit diameter 3.8 3.4 3.9

Orbit and spiracle length 5.2 5.1 5.9

Spiracle length—main pore 2.4 2.4 2.9

Distance between orbits 4.4 4.6 5.1

Distance between spiracles 5.6 5.9 6.5

Distance-snout to cloaca 47.8 52.1 56.2 Cloaca to D1 32.1 27.1 31.5 Cloaca to D2 40.5 35.5 39.2 Cloaca to caudal origin 45.9 40.8 44.2 Distance-cloaca to caudal fin tip 52.2 43.8 47.9 Snout length (pre upper jaw) 14.7 16.5 18.1 Prenasal length 12.4 13.1 14.4 Head length to fifth gill 29.0 30.2 32.3 Mouth width 7.7 8.3 10.0 Distance between nostrils 7.3 7.7 8.5

Nasal curtain-length 4.5 4.8 5.7

Nasal curtain-total width 9.5 10.3 10.5 Nasal curtain—min width 4.8 5.7 6.2

Nasal curtain—lobe width 2.5 2.1 2.6

Width of first gill opening 1.6 1.7 2.0

Width of fifth gill opening 1.1 1.1 1.4

Distance between first gill openings 14.3 16.7 17.4 Distance between fifth gill openings 7.5 9.3 10.1 Clasper-post cloacal length 21.4 - -

Length of anterior pelvic lobe 12.5 12.6 14.5 Length of posterior pelvic lobe 17.5 15.9 18.0 Pelvic base—width 9.8 10.9 11.8 Tail at axil pelvic fins—width 4.2 3.5 4.7

Tail at axil pelvic fins—height 2.2 2.0 2.6

Tail at midlength—width 1.6 1.9 2.2

Tail at midlength—height 1.1 1.1 1.3

Tail at D1 origin—width 1.5 1.5 1.7

Tail at D1 origin—height 1.0 1.0 1.0

D1 base—length 5.1 4.9 5.6

......continued on the next page Adult male Ranges for 5 female types D1—height 1.9 1.8 2.5 D1 orig to caudal fin tip 20.1 15.6 18.6 D2 orig to caudal fin tip 11.8 8.4 9.8 interdorsal distance 3.2 1.7 5.0 caudal fin length 6.4 2.4 5.1

Figures

FIGURE 1. Orbiraja jensenae, adult male (PNM 10300, 402 mm TL, Philippines, preserved): A, dorsal surface; B, ventral surface.

FIGURE 2. Orbiraja jensenae, head of adult male (PNM 10300, 402 mm TL, Philippines, preserved): A, dorsal surface; B, ventral surface.

FIGURE 3. Orbiraja jensenae, lumbar denticles in adult male (PNM 10300, 402 mm TL, Philippines, preserved).

FIGURE 4. Median thorn rows at the tail midlength in Orbiraja jensenae, adult male (PNM 10300, 402 mm TL, Philippines, preserved).

FIGURE 5. Lateral profile of the dorsal and caudal fins of Orbiraja jensenae, adult male (PNM 10300, 402 mm TL, Philippines, preserved).

FIGURE 6. Right clasper glans of Orbiraja jensenae, adult male (PNM 10300, 402 mm TL, Philippines, preserved). Abbreviations: cf = cleft, ep = eperon, rh = rhipidion, sh = shield, sk = spike, st = sentinel, tb = terminal bridge.

FIGURE 8. Orbiraja jensenae, adult male (PNM 10300, 402 mm TL, Philippines), terminal right clasper skeleton in ventral view, with ventral terminal cartilage. Abbreviations: at 1 to 3 = accessory terminals 1 to 3, ax = axial, tb = terminal bridge, vm = ventral marginal, vt = ventral terminal.