Telatrygon biasa, Last, Peter R., White, William T. & Naylor, Gavin, 2016
treatment provided by
Telatrygon biasa sp. nov.
Dasyatis sp.: Last et al., 2016: fig. 1 (molecular data).
Telatrygon sp.: Last et al., 2016: fig. 5 (molecular data).
Paratypes. 9 specimens. CSIRO H 4426-05, female 243 mm DW, CSIRO H 4426-06, male 195 mm DW, CSIRO H 4426-07, female 251 mm DW, CSIRO H 4426-09, male 191 mm DW, CSIRO H 4426-10, male 185 mm DW, Muara Angke fish market (probably collected in western Java Sea), Jakarta, Java, Indonesia, 17 Oct 1995 ; CSIRO H 5474-21 (field no. MMKK 68), female 253 mm DW, CSIRO H 5474-22 (field no. MMKK 71), male 205 mm DW, CSIRO H 5474-24 (field no. MMKK 74), mature male 196 mm DW, Kota Kinabalu fish market, Sabah, Borneo, Malaysia, 15 Feb 1999 ; CSIRO H 5475-06 (field no. MMKK 18), female 254 mm DW, Kota Kinabalu fish market, Sabah, Borneo, Malaysia, 9 Feb 1999 .
Diagnosis. A species of Telatrygon distinguished by the following combination of characters: snout relatively short, preorbital length 28–29% DW, preoral length 27–28% DW, prenasal length 23–25% DW; disc relatively short, length 97–105% DW; preoral length 1.5–1.6 times width between the first gill openings; eyes small, orbit length 5–7% DW; pectoral-fin radials 107–114; total vertebral centra (excluding 1st synarcual) 85–94.
Description. Disc rhombic, angular anteriorly and apex produced as firm lobe; its width 0.95 times length in holotype (0.97–1.03 in paratypes); axis of greatest width almost over scapular region, its distance from snout tip 1.70 (1.62–1.79) of distance from tip of snout to pectoral-fin insertion; body very depressed, thin, greatest thickness 10.8 (8.99–10.8) times in disc width, barely raised above cranium or above scapular region; anterior margin of disc concave, strongest beside orbits; apex broadly rounded, anterior disc angle 83° (84–91°), pectoral angle 100° (98–101°); posterior margin convex; free rear tip narrowly rounded. Pelvic fins strongly subtriangular; anterior margin almost straight, posterior margin convex or straight; apices narrow and bluntly pointed; free rear tip broadly rounded, inner margin short; very small, length 19.3% (16.2–19.2%) DW; 1.46 (1.15–1.41) times width across fin bases.
Tail very elongate, slender, postcloacal tail damaged (1.60–2.32) times precloacal length; with a long, low ventral skin fold and usually a much shorter dorsal skin fold; base moderately depressed, suboval in cross-section, weakly convex above and below, width 1.22 (1.35–2.04) times its depth; tapering strongly and evenly to sting base; broadly oval in cross-section near origin of ventral skin fold, width 1.18 (1.24–1.43) times height at fold origin; tapering abruptly below sting insertion; very slender and filamentous beyond sting; variable in cross-section above mid ventral fold, its width 0.57 (0.65–1.20) times depth; at end of ventral fold variably suboval, width 1.03 (0.48– 1.32) times height; dorsal surface of tail posterior to sting base with a narrow, tapering, naked groove (presumably housing sting when present); no skin folds or ridges along lateral margin of tail. Dorsal skin fold very low (but always present), merging with a low fleshy ridge anteriorly and posteriorly (fold origin and insertion not well defined); elongate, length about 28 (37–64) times its height, 2.28 (1.03–1.84) in snout length, 4.65 (2.99–3.92) in length of ventral fold; its height 1.39 (0.86–2.05) in height of mid ventral fold. Ventral skin fold very elongate, low, length 1.64 (1.21–1.62) in disc width, damaged in holotype (0.95–1.3 in paratypes) in post cloacal tail; origin 3.5% (3.7–15%) DW after sting origin; depth at quarter length 0.86 (0.61–1.05), at mid length 0.43 (0.41–0.82), at three quarter 0.82 (0.45–0.71) in adjacent tail height; originating posteriorly to sting origin; origin usually distinct but fold usually terminating in low fleshy ridge; distance from cloaca to sting origin 2.37 (2.49–2.94) in precloacal length; length of tail beyond ventral fold damaged (0.95–1.33) in fold length, damaged (2.40–3.12) in tail length. Sensory canals well demarcated on ventral surface.
Snout very elongate, strongly depressed, triangular; apex with a long, narrowly rounded lobe; angle 83.5° (83– 92°); preoral snout length 3.06 (2.98–3.47) times mouth width, 2.38 (2.47–2.82) times internarial distance, 1.62 (1.52–1.63) times distance between first gill slits; direct preorbital snout length 2.90 (2.62–2.88) times interorbital length; snout to maximum disc width 1.72 (1.76–1.94) in DW; interorbital space rather broad, slightly concave medially; eye small, dorsolateral, not protruded, its ventral margin partly covered by thin skin fold; orbit not elevated above interorbit, its diameter 1.07 (0.91–1.26) in spiracle length; eye diameter 1.50 (1.37–1.90) in spiracle length; inter-eye distance 3.59 (3.42–3.99) times eye diameter. Spiracle suboval, enlarged, dorsolateral. Nostrils narrow, slit-like, parallel to slightly oblique; anterior margin not elevated; anterior nasal fold internal, narrow, membranous; oronasal groove usually well defined; internasal distance 1.99 (2.04–2.37) in prenasal length, 3.20 (2.69–3.01) times nostril length. Nasal curtain skirt-shaped, elongate, width 1.73 (1.68–1.78) times length; moderately bilobed; its surface flat, smooth, without a longitudinal medial groove and not covered with prominent sensory pores; apex recessible within lateral margin of oronasal groove; lateral margin almost straight, smooth edged; posterior margin finely fringed, weakly concave, following contour of lower jaw, abutting or falling slightly short of symphysis of lower jaw when mouth closed.
Mouth strongly arched in adult males, almost straight in females; jaws asymmetrical; lateral groove weak or absent. Upper jaw strongly arched in holotype, teeth concealed when mouth closed, symphysial part of jaw not projecting ventrally (not visible). Lower jaw very strongly convex, weakly concave at symphysis in all male types, only outer symphysial teeth visible when mouth closed in holotype; not projecting forward when mouth open, mouth not protrusible; skin on chin not fleshy, ridged nor papillate. Floor of mouth in adult male paratype ( CSIRO H 4426-09) lacking oral papillae, instead covered with a series of horizontal pleats of skin. Teeth both jaws small, with very long, pointed cups; cusps longer near symphysis than near corners of mouth; close-set in both jaws but not quincuncial; tooth row counts unclear, ~48 rows in upper jaw, ~42 rows in lower jaw.
Gill slits distinctly S-shaped, edges not fringed laterally; length of first gill slit 1.41 (1.26–1.61) times length of fifth gill slit, 2.83 (2.28–3.35) times in mouth width; distance between first gill slits 1.46 (1.62–1.84) times internasal distance, 0.32 (0.33–0.35) times ventral head length; distance between fifth gill slits 0.95(0.98–1.18) times internasal distance, 0.21 (0.20–0.23) times ventral head length.
Squamation. Disc and tail lacking dermal denticles in young or with weak denticles and small thorns confined to median dorsal row in adults. Adult male holotype (MZB KA- 93, 162 mm DW) with short row of 6 minute, globular denticles in nuchal region; no thorns on tail; 3 adult male paratypes ( CSIRO H 4426-06, 0 9, 10) with 6–9 globular to weakly lanceolate denticles in nuchal region, 3–6 much larger (but small and varying in size), narrowly lanceolate, thorn-like denticles on midline of tail forward of caudal sting. Female paratypes ( CSIRO H 4426-05, H 5475-06, H 5475-21) with 7–13 globular to weakly lanceolate denticles in nuchal region, followed by 0–13 similar post-scapular denticles on posterior disc; 5–9 much larger (but small and varying in size), narrowly lanceolate, thorn-like denticles on midline of tail forward of caudal sting. All type specimens with caudal stings missing at preservation. Distance from caudal sting base to pectoral-fin insertion 36.5% (29.2–32.7%) DW; distance from cloaca to caudal sting base 0.38 (0.32–0.36) in disc length.
Meristics. Total pectoral-fin radials of holotype 107–108 (paratypes 107–114, n=5). Total pelvic-fin radials adult male holotype 16 (paratypes 19–24). Total vertebral segments (excluding first synarcual centra) 85 (88–94); monospondylous centra (excluding first synarcual) 37 (31–36); diplospondylous centra 51 (52–61).
Coloration. When fresh (holotype): Dorsal surface uniformly yellowish greyish, eye golden; dermal denticles white. Ventral surface of disc white centrally; entire margin greyish pink (transparent distally), band broadest beside pectoral apex, sharply demarcated from white part of disc; pelvic fin similar to disc, marginal marking very broad; ventral tail white forward of caudal sting, uniformly yellowish beyond; clasper paler ventrally than dorsally. In preservative (holotype) brownish on dorsal surface; white ventrally with marginal band pale to dusky; dorsal surface of tail and tip brownish black, ventral fold dusky. Images of fresh non-type material similar to holotype or sometimes slightly more brownish in dorsal coloration.
Ratios are expresseđ as percentages of đisc wiđth.
……continued on the next page TABLE ³. (Continueđ)
Telatrygon biasa Telatrygon zugei Trygon zugei Size. Largest type 254 mm DW, but reported to reach 287 mm ( White & Dharmadi, 2007). Size at maturity for males 168–176 mm DW, and for females 178–193 mm DW. Birth size 70–90 mm DW.
Distribution. Western North Pacific, including Indonesia and Malaysian Borneo. Also reported from the Philippines by Herre (1953), but no specimens have been reported recently. Demersal on continental and insular shelves to ~ 40 m depth.
Etymology. Noun in apposition of the Indonesian and Malaysian word ‘biasa’ meaning ‘ordinary, common or normal’ used herein to reflect the frequent occurrence of this species in local fish markets. In Malaysian Borneo, the ray is known as Pari Biasa or Common Ray. Vernacular: Indonesian Sharpnose Ray.
Comparisons. Telatrygon is presently under review (PL) and comparative morphological details for the group have not been fully elucidated. However, the four species of the genus are widely divergent based on their NADH2 sequences (see Last et al., 2016; Fig. 1 View FIGURE 1 ). The Chinese lectotype (MNHN 2447) and paralectotype (MNHN 1987- 152) of the type species of the genus Telatrygon (i.e. T. zugei ), are juveniles and differ slightly in shape to adults (e.g. ASIZ P67338, ASIZ P72247 and FRIP 3504). The T. biasa adults differ from the T. zugei adults primarily in dimensions of the head (preorbital snout 28.1–29.0% vs. 30.7–32.8% DW in T. zugei ; preoral length 27.4–28.3% vs. 31.6–32.2% DW; prenasal length 22.6–24.6% vs. 25.9–27.1% DW), and the disc might be slightly smaller (length 96.9–105.1% vs. 105.4–106.6% DW). The spiracles also appear to be larger in T. biasa (length 5.7–6.5% vs. 5.1–5.3% DW), and the ratio of the preoral length to the width of the interspace between the first gill openings is smaller (1.52–1.63 vs. 1.74–1.78). The body shape of T. acutirostra (based on FRIP3600) differs significantly from material examined of both T. biasa and T. zugei : for example, much longer snout (length 39.9% vs. 28.1– 32.8% DW), longer prenasal (length 35.1% vs. 22.6–27.1% DW) and smaller eyes (orbit length 3.5% vs. 5.0–6.7% DW).
A stingray of the genus Telatrygon from the northern Indian Ocean, originally identified as Trygon zugei (e.g. Day, 1878 [pl. cxc, fig. 3]; Day, 1889) has a longer snout (i.e. length 32.5–36.4% DW) and smaller eye (i.e. orbit length 4.3–4.8% DW) than either T. biasa or T. zugei , and a shorter snout and larger eye than T. acutirostra . This northern Indian Ocean species is referrable to Telatrygon crozieri ( Blyth, 1860) .
Nishida & Nakaya (1988) designated a lectotype for Dasyatis zugei and provided a detailed explanation for their reasoning. The larger of two preserved specimens, a juvenile male 137 mm DW (reported to be MNHN 1987- 152 View Materials ) was selected as the lectotype ; the second specimen (MNHN 2447), a smaller male of 106.6 mm DW, was selected as a paralectotype. However , the MNHN collection catalogue (https://science.mnhn.fr/institution/mnhn/ search) and specimen label both list the larger of the two as the lectotype, but as MNHN 2447 View Materials (rather than MNHN 1987-152 View Materials ). Whether this is a labelling error, or Nishida & Nakaya (1988) accidentally mixed up the numbers in the manuscript, is uncertain. We have followed the MNHN collection database, and current labelling for the more intact, larger specimen ( MNHN 2447 View Materials ), as the lectotype .
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.