Carcharhinus tjutjot ( Bleeker, 1852 )

White, William T., 2012, A redescription of Carcharhinus dussumieri and C. sealei, with resurrection of C. coatesi and C. tjutjot as valid species (Chondrichthyes: Carcharhinidae), Zootaxa 3241, pp. 1-34 : 23-27

Carcharhinus tjutjot ( Bleeker, 1852)

Figs 11 –13; Table 2

Carcharias (Prionodon) tjutjot Bleeker, 1852: 36 , pl. 1 (fig. 4) (Type locality: Jakarta, Indonesia).

Carcharias (Prionodon) javanicus Bleeker, 1852: 38 , pl. 2 (fig. 5) (Type locality: Jakarta, Indonesia).

Lectotype. RMNH 7382, subadult male 585 mm TL, Jakarta (as Batavia), Indonesia, collected by P. Bleeker. Paralectotype. BMNH 1867.11.28.177 (syntype), subadult male 611 mm TL, Jakarta (as Batavia), Indonesia, collected by P. Bleeker.

Other specimens. 8 specimens: BMNH 1867.11.28.188 (holotype of C. javanicus ), female 467 mm TL Jakarta (as Batavia), Indonesia, collected by P. Bleeker; CAS 228336, juvenile male 498 mm TL, Tashi fish market, Taiwan, 24th May 2005, collected by W. White and D. Ebert; CSIRO H 5861–07, female 342 mm TL, Muara Baru fish market, Jakarta, Indonesia, 18th March 2002, collected by W. White and Dharmadi; CSIRO H 7293–07, subadult male 712 mm TL, Muara Angke fish landing site, Jakarta, Indonesia, 6th December 2005, collected by W. White and Dharmadi; CSIRO H 7119–01 (jaws only), female 812 mm TL, Cilacap, Central Java, Indonesia, 9th August 2010, collected by W. White and Dharmadi; MZB 15084, 585 mm TL, Muara Angke fish landing site, Jakarta, Indonesia, 27th June 2001, collected by W. White; MZB 15107, juvenile male 404 mm TL, Muara Angke fish landing site, Jakarta, Indonesia, 18th March 2002, collected by W. White & Dharmadi; RMNH 7375, subadult male 643 mm TL, Indonesia, collected by P. Bleeker.

FIGURE 13. Dentition of Carcharhinus tjutjot ( CSIRO H 7119–01, female 812 mm TL): A. 5th upper anterolateral tooth on right side; B. 3rd lower anterolateral tooth on right side.

Diagnosis. A small species of Carcharhinus with: a relatively long and bluntly pointed snout; upper anterior teeth oblique and blade-like, coarsely serrated, lateral margin deeply notched and with several large and serrated basal cusplets; lower anterior teeth narrower, slightly oblique, lateral margins notched and without large basal serrae, finely serrated; total tooth row counts 26–28/24–30 rows or 51–55; interdorsal space usually with a moderate to strong ridge, 19.4–22.0% TL; first dorsal fin relatively low and not falcate, origin over middle of pectoral-fin inner margin, length 14.1–15.6% TL, 1.4–2.0 times height, inner margin 2.0– 2.7 in base; second dorsal fin much smaller than first, broadly triangular, height 29–37% of first dorsal fin height, origin slightly posterior of anal-fin origin; anal fin slightly falcate, height 0.9–1.3 times second dorsal-fin height, base 0.9–1.2 times second dorsal-fin base; colour pale brownish dorsally, whitish ventrally; second dorsal fin with a black blotch on upper third of fin, not extending onto upper surface of body and very well defined from whitish region below; other fins mostly plain; total vertebral counts 113–129; monospondylous precaudal counts 37–44; diplospondylous precaudal counts 17– 19; diplospondylous caudal counts 58–72; precaudal counts 55–63.

Description. Body relatively slender, trunk almost pear-shaped in section at first dorsal-fin base, length of trunk from fifth gill slits to vent 0.98–1.16 times head length; no predorsal or postdorsal ridges; interdorsal ridge usually present, moderate to strong; lateral ridges absent. Caudal peduncle moderately stout, roughly hexagonalshaped in section at second dorsal-fin insertion, postdorsal and postventral spaces flattened and with a very shallow median groove, lateral surfaces somewhat angular, no lateral ridges; height of caudal peduncle at 2nd dorsal-fin insertion 1.21 (0.95–1.24) times its width, 2.28 (2.23–2.65) times in dorsal–caudal space. Precaudal pits prominent; upper pit a pronounced, deep, arcuate and crescentic; lower pit smaller and shallower.

Head length to 5th gill opening 0.97 (0.79–0.98) times in pectoral–pelvic space; relatively stout, slightly flattened anteriorly, ellipsoidal in shape in cross-section at eyes. Outline of head in lateral view slightly undulated dorsally, medially slightly concave on snout, nearly straight above eye, concave at nape and convex to nearly straight and progressively elevated above gills to first dorsal fin; nearly straight ventrally along lower jaws and beneath gills. In dorsoventral view, head narrowly parabolic to pointed anteriorly. Snout relatively long, preoral snout length 0.79 (0.69–1.09) times mouth width; tip bluntly pointed in dorsoventral view and sometimes weakly indented anterior to nostrils; snout pointed in lateral view, slightly convex above and below.

External eye opening of fleshy orbit without anterior or posterior notches. Eyes moderately large, subcircular, height 1.38 (1.20–1.48) in length; length 10.45 (8.29–11.19) times in head length; situated laterally on head; subocular ridges absent. Nictitating lower eyelids internal, with deep subocular pouches and secondary lower eyelids fused to upper eyelids.

Spiracles absent. Gill slits large, first four subequal in height, third and fourth gill openings largest, fifth smallest; fifth slit about 0.85 (0.67–0.83) of height of third; height of third about 6.26 (5.85–8.96) in head length, 1.67 (0.92–1.69) times eye length; margins of first four gill slits nearly straight, fifth and sometimes first slightly concave; upper edges of gill slits 2 and 3 most elevated, upper ends about level with upper three quarters of eye. Gill filaments not visible from outside in lateral view. Gill-raker papillae absent from gill arches.

Nostrils with moderately large, subcircular incurrent apertures; moderately long, triangular anterior nasal flaps with narrowly pointed tips, posterior nasal flap vestigial, small circular excurrent apertures; well in front of mouth; width 2.55 (2.61–3.06) in internarial width, 1.33 (1.23–1.51) in eye length, 2.33 (1.29–2.34) in longest gill-opening.

Mouth moderately arched and moderately large; width 3.07 (2.80–3.28) in head length; mouth length 1.44 (1.46–1.86) in mouth width. Lips concealing teeth when mouth is closed. Tongue large, flat and broadly rounded, filling floor of mouth. Maxillary valve narrow, width much less than half of eye length, not strongly papillose. No large buccal papillae on floor or roof of mouth behind maxillary valve. Palate, floor of mouth and gill arches covered with buccopharyngeal denticles to at least first gill arch. Labial furrows small and barely visible in ventral view. Labial cartilages appear to be absent.

Teeth relatively few, in 26–28/24–30 rows or 51–55 total rows (both jaws, n=8). Teeth not arranged in diagonal files, no toothless spaces at symphysis. Teeth highly differentiated in upper and lower jaws and along jaws. Tooth formula (n=8): upper jaw 13 + 1–2 + 12–13, lower jaw 12–14 + 1 + 12–14. Upper anterolateral teeth with moderately broad, oblique, blade-like cusps; lateral margins deeply notched; medial margins slightly convex basally, nearly straight distally; several large cusplets basally on lateral margin; medial and lateral margins of cusp and the lateral basal cusplets with regular coarse serrations (Fig. 13a). Lower anterolateral teeth with narrower, only slightly oblique cusps; lateral margins not or slightly notched; medial margins concave; both margins finely serrated basally, distally almost smooth (Fig. 13b).

Lateral trunk denticles with flat, rhomboidal crowns wider than long, closely imbricate; crowns mostly with 5 prominent longitudinal ridges that extend its entire length onto the cusps; medial cusp short but strong, with two pairs of lateral cusps. Denticles absent from insertion of the fins.

Pectoral fins moderately large, relatively broad, weakly falcate; anterior margin moderately convex, apices narrowly rounded; posterior margin slightly to moderately concave; free rear tip moderately rounded, inner margin moderately convex; base broad about 52 (48–57)% of fin length; length from origin to rear tip 0.99 (0.92–1.08) times anterior margin length; slightly larger in area to first dorsal fin; origin under fourth gill slit; fin apex level just posterior to first dorsal-fin insertion when fin is elevated and adpressed to body.

Pelvic fins triangular, not falcate; length of anterior margins 0.45 (0.39–0.46) of pectoral–fin anterior margins; area slightly larger than that of anal fin; anterior margin nearly straight; apices bluntly angular to rounded; posterior margin nearly straight; free rear tip narrowly rounded, inner margin nearly straight.

First dorsal fin relatively low, triangular, not falcate (slightly falcate in small juveniles); anterior margin slightly to moderately convex, shallowly concave basally, apex moderately rounded; posterior margin nearly straight near apex then moderately concave, mostly angling very slightly posteroventrally above free rear tip from apex; free rear tip acutely pointed, inner margin shallowly concave; origin over middle of pectoral-fin inner margin; midpoint of base 1.42 (1.08–1.95) times closer to pelvic origins than pectoral insertions; free rear tip just anterior to pelvic-fin origins by about an eye diameter. First dorsal-fin base 1.94 (1.72–2.23) in interdorsal space, 2.39 (2.42–2.72) in dorsal caudal margin; height 1.11 (0.96–1.44) in base; inner margin 2.25 (1.84–2.43) in height, 2.49 (2.00–2.66) in base.

Second dorsal fin low, small, broadly triangular, not falcate; height 0.37 (0.29–0.36) second dorsal-fin height; base 0.60 (0.52–0.65) times first dorsal-fin base; anterior margin concave basally, becoming slightly convex distally; apex somewhat angular; posterior margin slightly concave; free rear tip acutely pointed, inner margin nearly straight; origin well behind pelvic-fin free rear tips and just posterior to anal-fin origin; rear tip just posterior to anal-fin free rear tip, in front of upper caudal-fin origin by 0.99 (0.92–1.56) times its inner margin length; posterior margin curving strongly posteroventrally from apex; insertion slightly posterior to level with fin apex. Second dorsal-fin base 1.36 (1.27–1.52) in dorsal–caudal space; height 1.78 (1.69–2.47) in base; inner margin 1.21 (0.94– 1.59) in height, 1.47 (1.34–1.91) in base.

Anal fin moderately falcate; height 1.13 (0.94–1.35) times second dorsal-fin height, base length 0.93 (0.97– 1.22) times second dorsal-fin base; anterior margin slightly convex; apex moderately rounded; posterior margin concave; free rear tip acutely pointed, inner margin nearly straight; origin just anterior to second dorsal-fin origin; insertion just anterior to second dorsal-fin insertion, about level with fin apex; free rear tip in front of lower caudalfin origin by about its base length; posterior margin almost vertical and then abruptly posterodorsally from apex. No preanal ridges obvious. Anal-fin base 1.16 (0.96–1.44) in anal–caudal space; height 1.47 (1.52–2.11) in base; inner margin 0.93 (0.93–1.08) in height, 1.58 (1.59–2.02) in base.

Caudal fin narrow-lobed and asymmetrical, with short terminal lobe and prominent, long, narrow, non-falcate ventral lobe; dorsal caudal margin proximally and distally convex, and slightly concave just anterior to subterminal notch, with prominent lateral undulations; preventral margin convex, tip of ventral caudal-fin lobe bluntly angular to angular; lower postventral margin nearly straight (slightly convex in small juveniles); upper postventral margin nearly straight except for convex section at subterminal notch; subterminal margin nearly straight; terminal margin slightly to moderately concave and irregular, lobe formed by these margins bluntly angular, tip of tail narrowly rounded. Length of dorsal caudal margin 2.89 (2.59–2.92) in precaudal length, preventral caudal margin 2.28 (2.17–2.78) in dorsal caudal margin, terminal lobe from caudal tip to subterminal notch about 3.45 (3.24–4.06) in dorsal caudal margin, subterminal margin length 1.71 (1.37–1.87) in terminal margin.

Counts of total vertebral centra (TC) 113–129, precaudal centra (PC) 55–63, monospondylous precaudal (MP) centra 37–44, diplospondylous precaudal (DP) centra 17–19, diplospondylous caudal (DC) centra 58–72; MP centra 28.9–35.5%, DP centra 15.0–15.8%, and DC centra 49.2–55.8% of TC centra. Ratios of DP/MP centra 0.43– 0.48, DC/MP centra 1.39–1.92. MP-DP transition often difficult to precisely locate, forming a`stutter zone' of alternating long and short centra.

Colour. Dorsal surfaces pale brownish to greyish when fresh, whitish ventrally and on lower sides. Demarcation between darker dorsal and paler ventral colours (waterline) extending from snout to mid-eye, then from upper margin of posterior eye through upper level of gill slits above pectoral-fin base horizontally to below posterior first dorsal fin, then extending dorsally to about midlevel of sides; extending through to end of caudal peduncle; edge of waterline mostly diffuse, sharpest on head and caudal peduncle. First dorsal fin without markings; second dorsal fin with a very distinct black apical blotch on upper third of fin, distinctly whitish below black blotch, very distinct from ground colour of fin; pectoral, pelvic, anal and caudal fins usually with pale outer margins.

Size. Specimens examined in this study ranged from 342–812 mm TL. White (2007) recorded males and females ranging in length from 404–937 and 341–918 mm, respectively, from southern Indonesian waters; males first mature at 751–775 mm TL; one pregnant female contained two late-term embryos (278 and 285 mm TL).

Teshima & Mizue (1973) examined the reproductive biology of this species off Kuching ( Sarawak, Malaysian Borneo) and reported that pregnant females usually contained only two embryos with the largest embryo recorded 373 mm TL and the smallest free-swimming individual 380 mm TL. Size at birth in this species is thus between 340 and 380 mm TL. Yano et al. (2005) reported two mature females of 758 and 790 mm TL off Sandakan (Sabah, Malaysian Borneo), and the smallest mature male was 710 mm TL and the largest immature male was 722 mm TL.

Distribution. Specimens examined were collected from Indonesia and Taiwan (although the exact capture locality is not known and could possibly have been from the South China Sea); also recorded from off Borneo; not found in Australia or New Guinea, where it is replaced by C. coatesi , and not confirmed from west of the Indo – Malay Peninsula; inshore species, likely in less than 100 m depth. Capture locations of examined specimens shown in Figure 4 .

Etymology. Bleeker described this species in 1852 and named it tjutjot . This is an Indonesian word spelt in the old Indonesian language that was altered following Indonesian independence. The use of “ tj ” was replaced by “ c ”, with both the old and the new spelling used for the sound ‘ch’. Indonesian for shark is most commonly either “ ikan hiu ” or “ cucut ”, thus it appears as if Bleeker named this species after an Indonesian word for shark which at the time would have been spelt tjutjot . Pronunciation of tjutjot should be (choo-choot).

Figures

FIGURE 4. Locality records for the type and other examined specimens, including other verified records, for the four species in the sealei-dussumieri complex: C. coatesi holotype (hollow circle) and other specimens (solid circles); C. dussumieri lecto- and paralectotypes (hollow stars) and other specimens (solid stars); C. sealei neotype (hollow square) and other specimens (solid square); C. tjutjot lecto- and paralectotype (hollow triangle) and other specimens (solid triangles); C. sp. (cross).

FIGURE 11. Lateral view of Carcharhinus tjutjot: A. lectotype RMNH 7382 (subadult male 585 mm TL), preserved; B. CSIRO H 7293 – 07 (subadult male 712 mm TL), fresh.