Pastinachus solocirostris, Peter R. Last, B. Mabel Manjaji & Gordon K. Yearsley, 2005

Peter R. Last, B. Mabel Manjaji & Gordon K. Yearsley, 2005, Pastinachus solocirostris sp. nov., a new species of Stingray (Elasmobranchii: Myliobatiformes) from the Indo-Malay Archipelago., Zootaxa 1040, pp. 1-16 : 3-14

Pastinachus solocirostris sp. nov.

(Figs. 1-6)

Holotype: IPMB 38.32.03, 411 mm DW, mature male, Mukah Fish Market, Mukah, Sarawak ( Malaysia), Borneo, South China Sea, coll. by P. Last, 30 Apr. 2004.

Paratypes: 14 specimens. CSIRO H 4426-27, 415 mm DW, mature male, tail missing, Muara Angke Fish Market, Jakarta, Java ( Indonesia), Java Sea, coll. by P. Last, 17 Oct. 1995 ; CSIRO H 5472-02, 270 mm DW, female, Kuching Fish Market, Kuching, Sarawak ( Malaysia), Borneo, South China Sea, coll. by B. Manjaji, 29 Jan. 1999 ; CSIRO H 5485-03, 418 mm DW, mature male, tail missing, Kuching Fish Market, Kuching, Sarawak ( Malaysia), Borneo, South China Sea, coll. by P. Last, 2 May 1999 ; CSIRO H 5485-04, 446 mm DW, female, same data as CSIRO H 5485-03 ; CSIRO H 5485-05, 359 mm DW, mature male, tail missing, same data as CSIRO H 5485-03 ; CSIRO H 5864-01, 244 mm DW, immature male, Miri Fish Market, Miri, Sarawak ( Malaysia), Borneo, South China Sea, coll. by P. Last and B. Manjaji, 24 May 2002 ; CSIRO H 5864-02, 275 mm DW, immature male, same data as CSIRO H 5864.01 ; CSIRO H 6123-02, 378 mm DW, mature male, Sematan Fish Market, Sematan, Sarawak ( Malaysia), Borneo, South China Sea, coll. by J. Caira, 14 May 2003 ; CSIRO H 6123-03, 132 mm DW, male embryo, same data as CSIRO H 6123-02 ; CSIRO H 6133-03, 390 mm DW, mature male, Muara Angke Fish Market, Jakarta, Java ( Indonesia), coll. by W. White, 16 May 2002 ; CSIRO H 6219- 01, 416 mm DW, female, Sematan Fish Market, Sematan, Sarawak ( Malaysia), South China Sea, coll. by J. Caira & K. Jensen, 15 May 2003 ; IPMB 38.18.01, 403 mm DW, mature male, Sipitang Fish Market, Sabah ( Malaysia), Borneo, South China Sea, coll. by B. Manjaji, 10 Apr. 1999 ; IPMB 38.18.02, 440 mm DW, female, same data as IPMB 38.18.01 ; IPMB 38.30.01, 415 mm DW, female, Kuching Fish Market, Kuching, Sarawak ( Malaysia), Borneo, South China Sea, coll. by B. Manjaji, 28 Jan. 1999 .

Diagnosis. A relatively small Pastinachus with the following combination of characters: snout acute, angle less than 110°, covered to apex with enlarged denticles; disc length 94-101% DW; head length 47-51% DW; preoral length 21-25% DW; distance between nostrils 9-11% DW; distance between first gill slits 20-25% DW; tail moderately compressed above midbase of ventral cutaneous fold, width 0.7-0.9 times its height; ventral fold slender, its length 1.1-1.3 times DW, 32-41 times its depth below its midbase; ventral fold depth 1.8-2.4 times tail height at its midbase; distance from cloaca to sting 0.9-1 in precloacal length; 1-3 nuchal thorns, largest pearl shaped; pectoral-fin radials 113-120; monospondylous vertebral centra 35-38.

Description. Disc quadrangular, anteriorly angular and slightly produced, length slightly shorter than width; width 1.06 times length in holotype (1.02-1.06 in paratypes); axis of greatest width of disc well (slightly in some paratypes) in advance of nuchal thorns, 1.85 (1.68-1.97) times in distance from tip of snout to pectoral-fin insertion; body thickness 6.2 (5.6-7.3) times in disc width, raised slightly above cranium (marginally more so above nuchal area); anterior margin of disc weakly concave anteriorly, weakly convex before apex (almost straight in some paratypes); pectoral apex broadly rounded, posterior margin moderately convex, free rear tip narrowly rounded (Fig. 1). Pelvic fins subtriangular, anterior and posterior margins almost straight, free rear tip narrowly rounded; length moderate, 22.8% (19.3-24.8%) DW; 1.27 (1.21-1.47) times width across fin bases. Tail moderately elongate, postcloacal tail 3.09 (2.65-3.98) times precloacal length; base moderately depressed, width 1.45 (1.45-2.09) times height, weakly convex above and below, narrowly rounded laterally; tapering gently and evenly to origin of ventral cutaneous fold, width 1.38 (1.02-1.50) times height at fold origin; at end of sting slightly depressed, with broad, strongly tapering naked post-sting groove on dorsal surface; at mid-fold moderately compressed, oval, width 0.83 (0.70-0.89) times height; at end of fold subcircular, width 1.11 (0.91-1.24) times height; finely filamentous, strongly depressed towards tail apex; no folds present along lateral margin of anterior pre-sting tail. Ventral cutaneous fold slender (Fig. 2), length 0.95 (0.77-0.90) in disc width, 2.35 (2.18- 2.59) in post cloacal tail; origin 3.3% (2.2-8.5%) before sting origin; depth at quarter length 1.14 (0.82-1.58), at mid length 1.89 (1.82-2.41), at three quarter 2.08 (1.99-3.44) times tail height; margin of terminal quarter of fold strongly indented in holotype (sometimes indented in paratypes, possibly through damage), stepped to its insertion, not terminating abruptly, continuing slightly more than orbit diameter along tail as a low, barely detectable ridge; distance from cloaca to sting origin 0.94 (0.87-0.96) in precloacal length; post-fold tail length 1.79 (1.16-2.85) in fold length, 4.21 (3.01-5.69) in tail length. Series of U-shaped clusters of sensory pores submarginal on posterior disc, pore clusters subequal to eye diameter. Lateral line on ventral surface indistinct.

Snout moderately elongate, acute at apex with indistinct, triangular apical lobe; angle 101° (92-109°); acutely subtriangular when viewed laterally, becoming more depressed towards apex, preoral snout length 2.69 (2.18-2.95) times mouth width, 2.26 (2.15-2.78) times internarial distance, 1.08 (0.90-1.04) times distance between first gill slits; direct preorbital snout length 1.88 (1.63-2.10) times interorbital length; snout to maximum disc width 2.10 (1.92-2.28) times in DW; interorbital space very broad, almost flat; eyes small, lateral, barely elevated, protruding slightly, ventral margin partly covered by thick, fleshy skin fold; orbit fused into head, barely discernable, diameter 1.36 (1.00-1.48) in spiracle length, eye diameter 2.13 (1.57-2.28) in spiracle length; inter-eye distance 6.17 (4.58- 6.25) times eye diameter length. Spiracles suboval, greatly enlarged, opening dorsolateral. Nostril slit-like, directed posterolaterally; anterior margin fleshy; anterior nasal fold internal, thin, membraneous; posterior lobe more greatly expanded and fleshy than anterior lobe, partly concealed beneath nasal curtain; oronasal groove present; internasal distance 1.90 (1.70-1.98) in prenasal length, 2.98 (2.26-3.23) times nostril length. Nasal curtain strongly bilobed, relatively broad, moderately long, flat, with no obvious longitudinal medial groove (confined to symphysis in holotype), weakly papillose or smooth, width 1.72 (1.60-1.93) times length, posterolateral apex recessible within lateral margin of oronasal groove; lateral margin slightly convex distally, smooth edged; posterior margin very finely fringed (sometimes obscure), strongly concave, following contour of lower jaw (Fig. 3), abutting symphysis of lower jaw when mouth closed. Jaws strongly asymmetric. Upper jaw very strongly arched (Fig. 4A), symphysial part of jaw projecting ventrally, forming a perpendicular angle with anterior lateral teeth, symphysial row orientated almost dorsoventrally; hind teeth almost perpendicular to those of mid-upper jaw; median teeth on jaw strongly arched posteriomedially, forming a deep groove between teeth of symphysis; lower jaw plate-like, subtriangular, symphysial teeth visible ventrally on jaw, lower palate concave behind symphysis; symphysis strongly protruded, abutting and slightly retracted into symphysis of upper jaw; lateral grooves shallow, near angles of jaws. Lower jaw projecting forward when mouth open (Fig. 4B), mouth not protrusible; skin on chin fleshy, weakly papillose to almost smooth; floor with 1+3+1 oral papillae (in holotype and paratypes CSIRO H 5485-05, H 6219-01) three central papillae coalesced basally, similar in height to those laterally; three palate ridges, converging anteriorly, coinciding with oral papillae when mouth closed. Teeth moderately large in size; those in symphysis of upper jaw much smaller than those posterolaterally; symphysial teeth in lower jaw similar in size to those laterally; crowns hexagonal, not club-shaped, without medial cusps, uniformly close-set in both jaws, arranged quincuncially; 20 rows visible in upper jaw in paratype CSIRO H 6219-01, with possibly 6-10 rows concealed on dorsoposterior portion of jaw; 25 rows in lower jaw in paratype CSIRO H 6219-01. Gill openings weakly to moderately S-shaped, forming a non-fringed lobed; length of first gill slit 1.58 (1.02-1.52) times length of fifth gill slit, 2.32 (2.16- 3.69) times in mouth width; distance between first gill slits 2.08 (1.97-2.58) times internasal distance, 0.44 (0.42-0.50) times ventral head length; distance between fifth gill slits 1.22 (1.19-1.53) times internasal distance, 0.26 (0.25-0.29) times ventral head length. Dorsal disc mostly covered in denticles and thick mucus, anterior margin of disc with denticles almost to pectoral apices; naked area (about equal to internasal distance) extending from widest part of disc to pectoral-fin insertion; naked area slightly greater in some specimens; pelvic fins and claspers naked; skin fold around rim of eye and posterior extremity merging into spiracle naked; denticles present on distal half of posterior wall of spiracle. Denticle band with three almost equally spaced pearl thorns (1-3, mostly 2, in paratypes, single or penultimate thorn always largest) (Fig. 5A); in holotype, mid-thorn distinctly larger, separated by diameter of largest thorn; denticles on mid-disc and interorbital space distinctly larger than those laterally, also slightly more widely spaced than those laterally; denticles becoming progressively smaller towards lateral margin of band; lateral margin of band with longitudinal denticle rows often separated by narrow naked strips; denticles covering entire snout, enlarged, less densely arranged than those on mid-disc, much larger than those along lateral margin (Fig. 5B); denticle band merging with tail at pectoral-fin insertion, not truncate or laterally expanded; entire dorsal and midlateral surfaces of tail covered with denticles at tail base, tail band covering about three quarters of dorsal surface of most of tail before skin-fold origin; most of tail behind skinfold origin scaled, ventral portion adjacent tail fold naked; skin fold naked, smooth or with fine ventroposteriorly directed striae; dorsal midline of tail behind sting with obvious, elevated, upright, acute subconical denticles, their height taller than denticles of snout, in mostly single series. Denticles of mid-disc stellate, crowns flat topped, barely raised, significantly narrower than their bases; denticles of anteror half of snout recurved, lanceolate (some narrow and feebly tricuspidate), pungent, posteriorly directed, widely spaced; ventral surface of disc and tail before and at base of ventral fold naked.

Mature male holotype with stinging spine missing, presumably removed and discarded (base intact); most paratypes with stinging spine missing or broken, about 16% DW in an adult male, CSIRO H 6133-03, about 13% in an embryo, CSIRO H 6123-03; two stinging spines present in paratype CSIRO H 6123-02, first significantly longer than second, subequal to shout length. Clasper strongly conical, slightly depressed, robust basally and tapering distally to a blunt point (Fig. 6).

The late prenatal pup (132 mm DW, CSIRO H 6123-03) has an obvious median denticle band; three conjoined, pearl-shaped nuchal thorns, middle thorn largest, last distinctly larger than first; denticle band well formed around cranium on snout, no denticles evident on snout; denticles in band stellate, partly embedded but obvious; band restricted in width behind head, broadest point subequal to interspiracular width; extending only onto anterior part of tail; eyes protruding slightly but not strongly stalked; lateral line evident on dorsal disc. Body shape and tail similar to adults, only the nuchal thorn length (3.6% DW), orbit diameter (6.6% DW), spiracle (9.4% DW), interorbital distance (17% DW), interspiracular distance (23% DW), distance between the fifth gill openings (15% DW), and all tail depths measured are relatively larger than in adults.

Total pectoral radials 119-120 (113-119); propterygials 53 (49-53), mesopterygials 16-18 (15-18) and metapterygials 49-50 (46-54). Total pelvic radials 22-24+1 in males (including holotype), 27-28 in females. Total vertebral segments 163 (163-171); postcranial monospondylous centra 38 (35-37); diplospondylous centra 125 (128-136).

Coloration. In fresh specimens, dorsal surface uniformly medium brown (sometimes tinged olive-green), somewhat pinkish toward disc margins, and on pelvic fins and claspers; tail to sting similar; darker brownish above skin fold, becoming progressively darker (almost black) towards tail tip; pelvic fins similar to outer disc; dorsal clasper similar to or darker than outer disc; skin fold often uniformly dark brown, sometimes with white base and occasionally mostly pale. Ventral surface of disc mostly pale (paratypes mostly white), somewhat more pinkish (becoming dusky in preserved specimens) around margin, on pelvic fin and clasper; tail brownish before skin fold, paler basally (often dusky in paratypes).

Size. Attains at least 446 mm DW (female). Seven mature males from 359-418 mm DW; largest immature male 275 mm DW. No data on size at birth but smallest specimen was a late male embryo of 132 mm DW.

Etymology. Derived by combination of the Latin solocis (rough or bristly) and rostrum (snout) in allusion to the unusually rough texture of the snout.

Common name. Roughnose Stingray.

Distribution. Indo -Malay Archipelago including Sarawak and south-west Sabah (Malaysian Borneo), Brunei, eastern Sumatra, and possibly Java (Fig. 7). Despite extensive sampling along the Sabah coast (the dryer parts of northern Borneo), Pastinachus solocirostris has only been recorded in the extreme south-west of that state, adjacent to Brunei. Sumatran material is recorded on the basis of digital images taken by Mr Fahmi (Lembaga Ilmu Pengetahuan Indonesia, LIPI) from fish markets in Riau province, north-east Sumatra. The catch location of specimens from the fish markets in Jakarta could not be determined. However, vessels suppling these markets often fish along the coasts of Sumatra and Borneo. Habitat possibly restricted as it appears to be most abundant near the coast in regions of high riverine outflow, particularly at and near Mukah, Sarawak.

Comparisons. Pastinachus , comprised of 6 nominal species, was thought to be monotypic. Most recent references to this genus (e.g. Bonfil and Abdallah, 2004; Nishida and Nakaya, 1990; Séret and McEachran, 1986) recognise a single species, P. sephen , which was described from material collected from Jiddah (Saudi Arabia) and Al Luhayyah (Yemen) in the Red Sea. A few other workers (e.g. Compagno, 2000) have recognised P. gruveli , but the validity of this species needs to be confirmed. To complicate matters, the types of P. (as Raja) sephen , as well as P. (as Raia) fluviatilis , and P. (as Raia) sancur , are not known (Eschmeyer, 2005). However, examinations of the extant types of Pastinachus (as Taeniura) atra , P. (as Trigon) forskalii and P. (as Dasybatus) gruveli , reveal stingrays with a similar disc shape to P. solocirostris , but they all have a shorter, more obtuse snout, no well-developed denticle patch on the snout apex, and a different combination of morphological characters.

Forsskål ’s description of P. sephen , which reveals a large stingray displaying the general characteristics of the genus, is not fully informative for distinguishing congenerics. He suggests that one of his types is of older age, apparently a mature male, with a disc slightly narrower than 1 m (3 ulnar in diameter, which is equivalent to about 3 feet). Adult males of P. solocirostris are much smaller, maturing at about 36 cm and are only known to reach 42 cm DW. A stuffed female (maturity stage unknown) from the Red Sea (SMF 2554, 57 cm DW) confirms that P. sephen is a larger ray than P. solocirostris (to 45 cm DW). The anterior disc of P. sephen is described by Forsskâl as semi-rhomboidal - characteristic of the more common and widespread, blunt-snouted, Indo-Pacific morphs typically referred to as P. sephen . Also, no mention is made of an acute, spiny snout that is typical of P. solocirostris .

The stuffed types of P. forskalii (SMF 2537, 25 cm DW; SMF 2538, 24 cm DW) collected from the Red Sea by Rüppell in 1828, along with the female specimen mentioned above and an additional nicely preserved specimen of P. sephen from the nearby Persian Gulf (off Kuwait, BPBM 33148, 27 cm DW), all have a short, relatively obtuse snout lacking a dense coverage of denticles. The Red Sea specimens, whose shape may have changed slightly due to being stuffed, are similar morphometrically to the Persian Gulf specimen, and collectively differ in shape from P. solocirostris . The specimens of P. sephen from near the type locality have a relatively shorter disc (disc length 75-84% versus 94-101% DW, precloacal length 67-76% versus 79-85% DW in P. solocirostris ), pre-sting tail length (cloaca origin to sting base 68-81% versus 85-94% DW), and ventral head proportions (head length 32-38% versus 47-51% DW, preoral length 12-15% versus 21-25% DW, prenasal length 10-12% versus 17-19% DW, internasal distance 7-9% versus 9-11% DW, and distance between first gill slits 16-20% versus 20-25% DW). The Red Sea specimens also have a much shorter-based (fold length 82-89% versus 105-130% DW) and deeper (fold depth below its midbase 3-3.4 times versus 1.8-2.4 times tail depth at same point, fold length 17-20 times versus 32-41 times its depth below midbase) ventral cutaneous fold. Studies in progress suggest that blunt-snouted forms of Pastinachus from across the Indo-Pacific may comprise more than a single species.