Rhynchobatus cooki, Last, Peter R., Kyne, Peter M. & Compagno, Leonard J. V., 2016

Last, Peter R., Kyne, Peter M. & Compagno, Leonard J. V., 2016, A new species of wedgefish Rhynchobatus cooki (Rhinopristiformes, Rhinidae) from the Indo – West Pacific, Zootaxa 4139 (2), pp. 233-247 : 235-244

Rhynchobatus cooki sp. nov.

( Figs.1–8 ; Table 1 )

Rhynchobatus sp. 1: Compagno & Last, 1999, p. 1422, fig.

Holotype. ZRC 41175, adult male 723 mm TL, Jurong fish market, Singapore, 0 7 Feb 1996.

Paratypes. 11 specimens: BPBM 19673, immature female 609 mm TL, Jakarta fish market, Java, Indonesia, 18 Feb 1975; CAS 13952, immature male 358 mm TL, immature female 415 mm TL, Singapore, March 1934; CAS 35592, male embryo 236 mm TL, Singapore, 22 Feb 1937; SAMC F039829 (5 specimens), immature male 395 mm TL, subadult male 642 mm TL, adult male 705 mm TL, adult male 733 mm TL, adult male 755 mm TL, Jurong fish market, Singapore, 0 7 Feb 1996; ZRC 41173, adult male 810 mm TL, Jurong fish market, Singapore, 0 7 Feb 1996; ZRC 41174, adult male 769 mm TL, Jurong fish market, Singapore, 0 7 Feb 1996.

Other material. 4 or 5 specimens (none retained). Photographic image, Muara Angke fish market (Jakarta, Indonesia), 22 Nov 1993; LJVC 960207 (missing), male embryo 209 mm TL, Jurong fish market, Singapore, 0 7 Feb 1996.

Diagnosis. A dwarf species of the genus Rhynchobatus (adults to 81 cm TL) with the following combination of characters: a very long, narrowly pointed snout, preoral snout 21–25% TL; eye small, length 5.1–6.6 in preorbital snout; interorbital space 3.2–4.0 in preorbital snout; mouth weakly bowed, with a strong indentation on upper jaw near symphysis and strong protuberance on lower jaw; tooth rows in upper jaw 32–39; two irregular rows of small rostral spines on distal third of snout, almost extending to snout tip but not distinctly paired; supraorbital spines small but well differentiated, discontinuous (present only on preorbit and beside spiracle); mid-dorsal spine row broken but well-developed in adults; only a few small scapular spines on shoulder (often obscure); origin of first dorsal fin slightly posterior to origin of pelvic-fin base; predorsal length 47–51% TL; colour dark greyish green above (when fresh) with variable pattern of white spots (not arranged in rows), juveniles more densely covered with large white blotches; dark cruciate marking on interorbital but no black pectoral marking; anterior pectoral disc and sides of tail with a broad white margin; a few dark transverse bars forward of dorsal fins; 66–72 precaudal free centra, 99–106 total free centra, 112–119 total centra (including synarcual centra); 48–52 total pectoral-fin radials.

Description. Body relatively delicate; snout in front of eyes narrowly pointed to weakly bottle-shaped, angle of about 45° in holotype; lateral margin of anterior half of snout weakly concave, then becoming strongly convex forward of eye to origin of pectoral fin. Preorbital length about 3.5 in holotype (3.4–4.0 in all paratypes) times interorbital width; preoral length 3.3 (3.2–3.6) times mouth width. Disc width across pectoral-fin apices 77% (73– 79% in adults and subadults exceeding 40 cm TL, 70–74% in juveniles smaller than 40 cm TL) of disc length (from snout tip to pectoral-fin free rear tips). Head strongly depressed, disc thickness 1.1 (0.7–1.4) times in interorbital space; ventral head length 3.1 (2.8–3.2) times TL; surface between eyes and spiracles almost flat. Tail moderately depressed; in cross section, strongly rounded both dorsally and ventrally, angular laterally, tapering evenly from pelvic-fin insertions; precloacal length 85% (84–105%) of length of tail from anterior vent to caudal-fin tip; width of tail at first dorsal-fin insertions of holotype 1.8 (1.2–2.0) times interspiracular distance. Lateral keels of tail extended forward as a prominent angular edge along precaudal tail, almost reaching just forward of first dorsal insertion; most strongly differentiated on caudal fin.

Horizontal eye (eyeball) diameter about 49% (48–63%, mainly 54–68%) of interspiracular width, distance from anterior margin of orbit to posterior margin of spiracle less than interspiracular width; greatest dimension of spiracles 53% (51–61%, 32–48%) of horizontal eye diameter; distance between spiracle and eye about half corneal length, membrane of orbit continuous with spiracular opening. Spiracle dorsolateral, anterior margin with a prominent valve, posterior margin with two narrow, spiracular folds, lateral fold slightly larger and directed anteromedially.

Nostrils diagonal, forming angle of ~45° with body axis, anterior ends directed slightly more laterally; internarial width 0.9 (0.9–1.2) times nostril width. Nasal cavity fully exposed, without dividing flaps; aperture straight anterolaterally, recurved slightly posteromedially. Anterior nasal flap narrow, low, anteromedial on nasal aperture, inserted near midlength of nasal aperture; anterior process short, simple, its base length about twice as long as its width. Posterolateral nasal flap low, narrow and elongated, weakly lobate; originating just behind anterior lateral edge of incurrent aperture, extending posteriorly to beyond midlength of nasal aperture. Posterior nasal flap low, short based; joined to undersurface of posterolateral flap at about anterior third of its length, junction concealed beneath posterolateral nasal flap; inserted beyond midlength of nostril. Mouth opening somewhat arcuate, weakly undulating to nearly straight laterally; strong medial depression on upper jaw corresponding to a very prominent anterior extension at symphysis of lower jaw. Labial folds and furrows short; shallow pockets, deep circumoral grooves, and low folds and depressions, surround jaws laterally to labial folds; depressions most prominent laterally and on lower jaw. Teeth in differentiated serial rows, ~39 (32–39) in upper jaw, ~34 (33–39) in lower jaw. First four gill openings subequal in length, the fifth slightly shorter; third gill opening 2.7 (2.3–3.0, 3.3–4.3) in internarial width, 2.9 (2.5–3.2, 3.4–3.7) times in nostril length, 1.2 (1.2–1.6, 1.0– 1.1) times length of fifth gill opening.

Holotype Large paratypes (> 400 mm) Juvenile paratypes (<400 mm) MIN MAX MIN MAX ......continued on the next page TABLE 1 . (Continued)

Holotype Large paratypes (> 400 mm) Juvenile paratypes (<400 mm) MIN MAX MIN MAX P2P—Pelvic-fin posterior margin length 9.7 7.7 9.5 6.2 7.9 P2I—Pelvic-fin inner margin length 9.7 0.8 8.5 5.7 6.8 P2S—Pelvic-fin span 18.1 16.8 19.8 13.9 18.2 CLO—Clasper outer length 8.6 7.3 9.3 1.7 2.3 CLI—Clasper inner length 15.5 15.4 18.8 7.2 10.4 ESL—Eye–spiracle space 4.8 0.0 0.0 0.0 0.0

......continued on the next page TABLE 1 . (Continued)

Holotype Large paratypes (> 400 mm) Juvenile paratypes (<400 mm) Dermal denticles minute (not distinguishable to naked eye), covering all of body surface, varying in shape between different parts of body; dense and compacted to weakly imbricate, no obvious exposed skin patches between them; slightly larger on snout than on interorbit. Dorsal denticles with tall pedicels and flat elevated crowns; crowns on trunk typically flattened, broad, subcircular, irregularly rounded anteriorly, variably unicuspidate or weakly tricuspidate posteriorly, sometimes with low longitudinal ridges. Ventral denticles usually lacking cusps, compacted; similar in size to those of dorsal trunk.

Spines small but prominent on dorsal surface of body and tail; in two variably formed rows on anterior third of snout; rostral spines extending almost to snout tip, somewhat deciduous and sometimes missing (their former presence evident as a naked pocket of skin). In holotype, rostral spines present at snout tip but becoming more widely spaced posteriorly; 3 (2–3 in paratypes) preorbital spines, short, subconical; no mid-orbital spines; 1–2 (1–2 in paratypes) smaller spiracular spines; single median series commencing on nape, extending posteriorly in broken row almost to first dorsal fin; spines largest and bluntly pointed on mid-scapular region; spines on midline of tail poorly developed, absent in holotype but present in interdorsal space as 4–5 few weak spines (usually nearest second dorsal fin); very small scapular spines present in short rows on each side of disc in holotype, just forward of level of pectoral-fin apices; anterior series obscure in types, with 0–2 very small spines; posterior series more obvious with 2–3 widely spaced spines, well separated from those anteriorly. Sensory pores well developed on ventral snout; also concentrated in two distinct transverse patches (between anterior nostril and just posterior to mid-preoral space).

Dorsal fins similar in shape, raked slightly, shark-like, with strongly convex anterior margins (weakly concave at base), bluntly pointed apices, weakly concave posterior margins, sharply acute free rear tips, and almost straight inner margins. First dorsal fin slightly larger than second, height of second dorsal fin 78% (74–95%) height of first; inner margin of fin 63% (61–74%) of its base length; origin slightly posterior to origins of pelvic fins; free rear tip well posterior to free rear tips of pelvic fin. Interdorsal space 2.0 (1.9–2.1, 1.9–2.3) times length of first dorsal-fin base, ~2.7 (2.2–2.8) of length of second dorsal-fin base. Caudal fin rather short; dorsal caudal margin 6.0 (5.9–6.8) TL, 1.2 (1.1–1.4) times longer than interdorsal space; dorsal caudal margin moderately convex, slightly concave near its origin; caudal-fin tip bluntly pointed; preventral caudal margin moderately convex, less so anteriorly; ventral lobe well developed, strong, angular (relatively shorter and less well-defined in juveniles); lower postventral caudal margin short, almost straight to weakly concave, 3.1 (2.6–3.8) in length of upper margin in adults; upper postventral margin undulate; caudal axis elevated slightly, forming a narrow angle with horizontal body axis. Pectoral fins short, originating just behind spiracles, margin very deeply concave at origin, becoming weakly convex toward apices; apices broadly pointed; posterior margins convex; free rear tips narrowly rounded to angular, inner margin extending 91% (75–103%) across pectoral–pelvic space; inner margins straight to weakly concave. Pelvic fins small, with weakly convex anterior margins; apices broadly rounded; posterior margins concave (more so anteriorly); free rear tips elongate and very narrowly pointed; inner margins straight to weakly concave, very long, length 1.8 (1.2–1.6) times length of pelvic-fin base; pelvic-fin base 1.0 (0.9–1.3) in pectoral– pelvic space; height of pelvic fins about 2.3 (2.1–2.9) in their length; distance between pelvic-fin insertions exceeding pelvic-fin base length. Vent with well-developed folds laterally; well separated from pelvic-fin inner margins. Clasper very elongate, very slender, weakly expanded distally at glans; their rear tips well short of origin of second dorsal fin.

Vertebral counts: 112–119 total centra in paratypes (n=9); 12–13 synarcual centra, 20–22 monospondylous centra, 66–72 precaudal free centra, 31–37 diplospondylous caudal (free) centra, 99–106 free centra. Total synarcual segments 10.3–11.6%, monospondylous 17.2–20.0%, diplospondylous precaudal centra 37.4–45.2%, and precaudal free centra 57.4–62.6% of total centra count. Pectoral fin: 48–52 total pectoral-fin radials, 0–3 free radials before propterygium, 16–17 propterygials, 4–6 mesopterygials, 3–5 neopterygials, 21–23 metapterygials, 47–50 total basal radials (excluding free radials).

Colour. Preserved (based on adult male holotype, ZRC 41175, 723 mm TL): Dorsal surface of body greyish brown with evidence of white spots and dark markings, particularly on head; a prominent dark bar between eyes extends anteriorly and posteriorly on mid-disc to form a cross-like marking; unpaired fins (more so their bases), margin of head, and posterior margins of pectoral and pelvic fins yellowish (much paler than central body); no dark marking at base of pectoral fins; spines yellowish, much paler than surrounding skin. Ventral surface uniformly whitish, no dark blotches or markings on snout; minute sensory pores demarcated, greyish.

Fresh coloration (based on 6 adult specimens photographed at Jurong fish market): Dorsal surface of body greyish green, dark and pale markings more obvious than on fixed specimens; cross-like marking on interorbit prominent, surrounded by 4 white blotches; two similar dark transverse bars (with white bar between) on mid body between eyes and first dorsal fin; rostrum dark with 1–2 white median blotches; edge of body noticeably white (broadest on head and along tail) when viewed from above; broad outer margin of pelvic fins and unpaired fins very pale (white or pale yellow) and strongly contracted with rest of body; a few bilaterally symmetrical, large whitish spots on pectoral fins and tail.

Embryo (CAS 35592, preserved): Dorsal surface of body brownish with light and dark markings larger and very prominent (more so than in adult); cross-like marking and associated white blotches on interorbit very prominent; white spots, blotches and streaks also much more pronounced on tail; pale fins and dark margin of body also prominent and strongly contrasted with brownish part.

Size. A small species of Rhynchobatus , reaching at least 810 mm TL; embryos with yolk sacs were 209 and 236 mm TL, a male 395 mm TL was juvenile, a male 642 mm TL was adolescent, and six males> 705 mm TL were adult; females 415 and 609 mm TL were immature.

Distribution. Specimens obtained from the Jurong fish market ( Singapore) and a Jakarta fish market (probably Muara Angke) ( Indonesia). Also observed at Muara Angke fish market (Jakarta, Indonesia) in the early 1990s. Fishers landing product at these markets operate widely across the Indo–Malay Archipelago so the providence of specimens are unknown. For example, fish landed at Jurong are unlikely to be from Singaporean waters, but may be from the South China, Java or Andaman Seas.

Etymology. Patronym proposed by one of us (LC) to honour the late Sid Cook, a pioneer in shark conservation who participated in surveys of chondrichthyan fishes in South-East Asia at the time specimens were collected. Vernacular: The name proposed here, Clown Wedgefish in recognition of its clown-like colour pattern, was coined by Lim Kok Peng (alias Kelvin) who participated in the collection of most of the types. Also referred to as the Roughnose Wedgefish ( Compagno & Last, 1999).

Comparisons. Shares with the much larger (to ~ 300 cm TL), Atlantic species Rhynchobatus luebberti , welldeveloped rostral spines, relatively small eyes, nearly straight tooth bands, pelvic fins with rounded apices, disc with a prominent white margin, and a cross-like marking on the interorbit (most obvious in young and subadults). Rhynchobatus luebberti differs from R. cooki sp. nov. in having a shorter, less hastate snout (preoral length 20– 21% TL vs. 21–25% in R. cooki sp. nov.); combined lateral margin of head and anterior pectoral fin much less undulate in adults (particularly deeply concave behind eyes in R. cooki sp. nov.); rostral spines more numerous and concentrated on rostral ridges, extending nearly to eyes (rather than confined to anterior third of snout); more numerous orbital spines, forming a complete series medial to the eyes (vs. patches strongly disjunct); many more spines in median and scapular series, at least 8 prescapular and 7 postscapular spines; both primary and secondary lateral prescapular spines present; interdorsal spines large and strong (otherwise weak); first dorsal-fin more posterior, origin closer to insertions of pelvic-fin bases (rather than slightly behind pectoral-fin origins); a pair of black blotches usually present on back (otherwise absent); a pair of black pectoral-fin ocelli surrounded by white spots often present (otherwise absent); and white spots on body small, numerous, not extending forward of eyes (some white spots present on snout). None of the other six Rhynchobatus species has rostral spines or such a low vertebral count (total free centra 106 or less vs. 117 or more).

Figures

FIGURE 1. Rhynchobatus cooki sp. nov., adult male holotype (ZRC 41175, 723 mm TL, preserved): (A) dorsal view; (B) ventral view.

FIGURE 2. Fresh specimens (including some paratypes) of Rhynchobatus cooki sp. nov., Jurong fish market, 0 7 Feb 1996. Note the small Rhynchobatus springeri at the right side of the image.

FIGURE 3. Snout, head and pectoral fins of Rhynchobatus cooki sp. nov., adult male holotype (ZRC 41175, 723 mm TL, preserved).

FIGURE 4. Rostral spines of Rhynchobatus cooki sp. nov.: (A) dorsolateral view of adult male holotype (ZRC 41175, 723 mm TL, preserved); (B) dorsal view of adult male paratype (ZRC 41174, 769 mm TL, preserved).

FIGURE 5. Mid-scapular thorns of Rhynchobatus cooki sp. nov., adult male holotype (ZRC 41175, 723 mm TL, preserved).

FIGURE 6. Oronasal region of Rhynchobatus cooki sp. nov., adult male holotype (ZRC 41175, 723 mm TL, preserved).

FIGURE 7. Fins of Rhynchobatus cooki sp. nov., adult male holotype (ZRC 41175, 723 mm TL, preserved): (A) first dorsal fin; (B) second dorsal fin; (C) caudal fin.

FIGURE 8. Dorsal view of Rhynchobatus cooki sp. nov.: male embryo (CAS 35592, 236 mm TL, preserved).

Tables

TABLE 1. Morphometric data for the adult male holotype of Rhynchobatus cooki sp. nov. (ZRC 41175) with ranges provided separately for six large paratypes (adults and subadults, 415 – 755 mm TL) and four juvenile paratypes (juveniles, 209 – 395 mm TL). Measurements expressed as percentages of total length.

TOT—Total length (mm)	723	415.0	755.0	209.0	395.0
FOR—Fork length	91.6	91.1	92.8	91.1	93.3
PCL—Precaudal length	83.3	82.5	84.6	81.8	84.8
PD2—Pre-second dorsal length	68.6	68.8	70.4	66.3	69.5
PD1—Pre-first dorsal length	47.7	47.1	50.6	50.2	50.8
PP2—Prepelvic length	45.8	44.9	49.8	46.3	47.9
SVL—Snout–vent length	46.1	45.7	51.3	47.9	49.9
PSP—Prespiracular length	21.9	20.7	24.7	22.9	24.8
PG1—Prebranchial length	27.9	26.7	30.9	27.3	30.3
HDL—Head length	32.0	31.1	35.7	33.0	35.2
POB—Preorbital length (direct)	18.6	18.1	20.7	18.7	20.9
POR—Preoral length	21.4	20.6	24.8	22.5	24.6
PRN—Prenarial length	16.8	15.1	18.4	16.4	18.4
IDS—Interdorsal space	14.3	13.0	14.8	11.6	13.4
DCS—Dorsal–caudal space	8.7	7.3	8.9	7.9	8.9
PPS—Pectoral–pelvic space	5.4	5.3	6.5	4.2	5.6
PCS—Pelvic–caudal space	31.6	29.5	33.6	28.3	30.6
PDS—Pelvic–dorsal space	3.3	2.5	3.4	2.2	4.8
DW—Disc width	34.9	34.6	36.1	33.0	35.4
DL—Disc length	45.2	44.4	48.8	46.9	47.8
DT—Disc thickness	6.0	4.9	6.4	3.8	7.6
Snout—greatest width	33.0	33.5	39.0	36.0	37.7
SWB—Snout width at base	14.8	14.4	16.3	14.9	17.1
COL—Corneal/eye length	1.6	1.5	2.4	2.4	3.0
COH—Corneal/eye height	0.9	0.9	1.1	0.9	1.1
EYL—Eye (eyeball) length	2.9	2.9	3.9	3.9	4.7
EYH—Eye (eyeball) height	2.0	1.9	2.3	2.2	2.9
INO—Interorbital space	5.3	4.6	8.7	5.7	9.7
SPL—Spiracle length	1.5	1.7	2.2	1.3	1.9
SPH—Spiracle height	1.8	1.6	2.2	1.6	3.0
ESL—Eye–spiracle space	4.8	0.0	0.0	0.0	0.0