Carcharhinus sealei ( Pietschmann, 1913 )

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 : 18-22

Carcharhinus sealei ( Pietschmann, 1913)

Figs 8 –10; Table 1

Carcharias sealei Pietschmann, 1913: 172 , pl. 1 (Type locality: Sandakan, Sabah, Malaysia); replacement name for Carcharias borneensis Seale, 1910: 263 , preoccupied by Carcharias (Prionodon) borneensis Bleeker, 1858 .

Holotype. BSMP 2720, destroyed during World War II.

Neotype: CSIRO H 4919–04, juvenile male 373 mm TL, Sandakan fish market, Sabah, Malaysia, 16th October 1996, collected by P. Last.

Other material. 13 specimens: CSIRO H 4131–03, female 370 mm TL, Novortas fish market, Manila, Philippines, 13°55’ N, 120°42’ E, 5th October 1995, collected by P. Last; CSIRO H 7292–01, juvenile male 614 mm TL, Selakau fish market, West Kalimantan, Indonesia, 01°03’ N, 108°58’ E, 11th July 2007, collected by J. Caira, K. Jensen and G. Naylor; CSIRO H 7293–01, juvenile male 542 mm TL, CSIRO H 7293–02, juvenile male 653 mm TL, CSIRO H 7293–03, female 541 mm TL, CSIRO H 7293–04, female 554 mm TL, CSIRO H 7293–05, female 482 mm TL, CSIRO H 7293–06, female 600 mm TL, MZB unreg 20778 (2 of 2), juvenile male 674 mm TL, MZB 20778 (2 of 2), female 609 mm TL, QM I 38859, juvenile male 542 mm TL, Muara Angke fish landing site, Jakarta, Indonesia, 6th December 2005, collected by W. White and Dharmadi; RMNH 7376 (2 specimens), female 515 mm TL, juvenile male 343 mm TL, Jakarta (as Batavia), Indonesia, collected by P. Bleeker.

Diagnosis. A small species of Carcharhinus with: a moderately long and bluntly pointed snout; upper anterior teeth oblique and blade-like, coarsely serrated laterally, lateral margin deeply notched and with several large and smooth basal cusplets; lower anterior teeth narrower, slightly oblique, lateral margins usually not notched and with several large basal serrae, mostly smooth; total tooth row counts 24–28/22–27 or 47–55; interdorsal space usually without a ridge on midline, 19.0–22.4% TL; first dorsal fin moderately tall and falcate, origin about opposite pectoral-fin free rear tip, length 14.7–16.0% TL, 1.3–1.7 times height, inner margin 2.1–2.7 in base; second dorsal fin much smaller than first, broadly triangular, height 31–37% of first dorsal fin height, origin slightly posterior to anal-fin origin; anal fin falcate, height 0.9–1.2 times second dorsal height, base 1.0–1.3 times second dorsal-fin base; colour pale brownish to grey dorsally, whitish ventrally; second dorsal fin with a black blotch covering most of fin and often extending slightly onto upper surface of body, usually diffuse-edged and poorly defined from ground colour of fin; other fins plain or with pale outer margins; total vertebral counts 146–163; monospondylous precaudal counts 42–48; diplospondylous precaudal counts 26–38; diplospondylous caudal counts 74–81; precaudal counts 71–82.

Description. Body slender, trunk almost pear-shaped in section at first dorsal-fin base, length of trunk from fifth gill slits to vent 1.14 (1.13–1.35) times head length; no predorsal or postdorsal ridges; interdorsal ridge usually absent, or very weak; lateral ridges absent. Caudal peduncle moderately stout, roughly hexagonal to squarish in section at second dorsal-fin insertion, postdorsal and postventral spaces flattened and usually with a very shallow median groove, lateral surfaces somewhat rounded to slightly angular; no lateral ridges or keels; height of caudal peduncle at 2nd dorsal-fin insertion 1.38 (1.05–1.41) times its width, 1.66 (1.87–2.27) times in dorsal–caudal space. Precaudal pits prominent; upper pit a pronounced, deep, arcuate and crescentic; lower pit smaller and shallower.

FIGURE 10. Dentition of Carcharhinus sealei ( CSIRO H 7292–01, juvenile male 614 mm TL): A. 3rd upper anterolateral tooth on right side; B. 3rd lower anterolateral tooth on right side.

Head length to 5th gill opening 0.95 (0.90–1.12) times in pectoral–pelvic space; moderately stout, not flattened, ellipsoidal in shape at 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 nearly straight to slightly convex and progressively elevated above gills to first dorsal fin; slightly convex to nearly straight ventrally along lower jaws and beneath gills. In dorsoventral view, head anteriorly narrowly parabolic. Snout moderately long, preoral snout length 0.94 (0.86–1.06) times mouth width; tip bluntly pointed in dorsoventral view and weakly indented anterior to nostrils; snout acutely rounded in lateral view, slightly convex above and below.

External eye opening of fleshy orbit without anterior or posterior notches. Eyes moderately large, circular in shape (sometimes slightly longer than high), with height 1.26 (1.04–1.93) in eye length, length 7.46 (6.72–9.94) times in head length; situated mostly lateral 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 moderately large, first four gill slits subequal in height, third and fourth gill openings subequal and largest, fifth smallest; fifth slit about 0.67 (0.69–0.91) of height of third; height of third 7.51 (6.69–8.08) in head length, 0.99 (0.89–1.48) times eye length; margins of first four gill slits usually weakly concave (sometimes straight), fifth weakly to moderately 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. Gillraker papillae absent from gill arches.

Nostrils with moderately large, subcircular incurrent apertures; moderate-sized, triangular anterior nasal flaps with pointed tips, posterior nasal flap vestigial, small circular excurrent apertures; well in front of mouth; width 2.62 (2.28–2.49) in internarial width, 1.66 (1.30–1.93) in eye length, 1.64 (1.31–2.00) in longest gill-opening.

Mouth moderately large, narrowly arched to narrowly rounded; width 3.04 (2.92–3.61) in head length; mouth length 1.61 (1.34–1.79) in mouth width. Lips concealing teeth when mouth is closed. Tongue large, flat and broadly rounded, filling floor of mouth. Maxillary valve narrow, width 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 second gill arch. Labial furrows inconspicuous, restricted to mouth corners and barely visible in ventral view. Labial cartilages appear to be absent.

Teeth relatively few, in 24–28/22–27 rows or 47–55 total rows (both jaws, n=16). 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=16): upper jaw 11–13 + 0–2 + 11–13, lower jaw 10–13 + 1–2 + 10–13. Upper anterolateral teeth with moderately broad, strongly to moderately oblique, blade-like cusps; lateral margins deeply notched; medial margins convex basally, nearly straight distally; several large cusplets basally on lateral margin; medial margin with coarse serrations on basal half, almost smooth distally; lateral margin without coarse serrae, mostly smooth; basal cusplets smooth, without serrations (Fig. 10a). Lower anterolateral teeth with narrower, slightly oblique cusps; lateral margins not or slightly notched and with about four small to large, smooth basal serrae; medial margins concave; both margins usually smooth (Fig. 10b).

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

Pectoral fins moderately large, relatively narrow, weakly falcate; anterior margin moderately convex, apices angular; posterior margin moderately concave; free rear tip moderately rounded, inner margin convex; base broad about 52 (49–53)% of fin length; length from origin to rear tip 0.91 (0.90–0.97) times anterior margin length; subequal in area to first dorsal fin; origin under fourth gill slit; fin apex just anterior to level of first dorsal-fin insertion when fin is elevated and adpressed to body.

Pelvic fins triangular and not falcate; length of anterior margins 0.40 (0.33–0.42) of pectoral–fin anterior margins; area slightly larger than that of anal fin; anterior margin nearly straight; apices bluntly angular; posterior margin nearly straight; free rear tip bluntly rounded to angular, inner margin nearly straight.

First dorsal fin moderately tall, falcate; anterior margin nearly straight and convex near apex, shallowly concave basally; posterior margin concave, angling anteroventrally from apex and then abruptly posteroventrally at free rear tip; free rear tip acutely pointed, inner margin shallowly concave; origin over or just anterior to pectoralfin free rear tip; midpoint of base 1.29 (1.21–1.45) times closer to pelvic origins than pectoral insertions; free rear tip just anterior to pelvic-fin origins by less than a half of eye length. First dorsal-fin base 1.85 (1.65–2.21) in interdorsal space, 2.60 (2.31–2.62) in dorsal caudal margin; height 1.22 (0.89–1.26) in base; inner margin 1.94 (1.97– 2.50) in height, 2.36 (2.11–2.70) in base.

Second dorsal fin small, broadly triangular, very weakly falcate; height 0.37 (0.31–0.37) second dorsal-fin height; base 0.55 (0.54–0.63) times first dorsal-fin base; anterior margin concave basally, becoming slightly convex distally; apex moderately rounded to bluntly angular; posterior margin slightly to moderately concave; free rear tip acutely pointed, inner margin nearly straight; origin well behind pelvic-fin free rear tips and posterior to anal-fin origin by about half an eye length; rear tip slightly posterior to anal-fin free rear tip, in front of upper caudal-fin origin by 0.77 (0.77–1.52) times its inner margin length; posterior margin curving posteroventrally from apex; insertion about level with fin apex. Second dorsal-fin base 1.25 (1.19–1.44) in dorsal–caudal space; height 1.82 (1.70–2.44) in base; inner margin 1.29 (0.91–1.35) in height, 1.41 (1.49–2.01) in base.

Anal fin falcate and apically narrow; height 1.07 (0.95–1.20) times second dorsal-fin height, base length 1.18 (0.99–1.28) times second dorsal-fin base; anterior margin moderately convex; apex bluntly angular to narrowly rounded; posterior margin deeply concave; free rear tip acutely pointed, inner margin nearly straight; origin slightly anterior to second dorsal-fin origin; insertion opposite or slightly anterior to second dorsal-fin insertion, about level with fin apex; free rear tip in front of lower caudal-fin origin by about half its inner margin length; posterior margin almost vertical and then abruptly posterodorsally from apex. No preanal ridges obvious. Anal-fin base 1.04 (0.98– 1.39) in anal–caudal space; height 2.01 (1.48–2.30) in base; inner margin 1.15 (0.92–1.19) in height, 1.74 (1.54– 2.15) in base.

Caudal fin very narrow-lobed and asymmetrical, with short terminal lobe and prominent, long, narrow, nonfalcate 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 narrowly rounded to somewhat angular; lower postventral margin almost straight; upper postventral margin nearly straight except for convex section at subterminal notch; subterminal margin nearly straight; terminal margin slightly concave to nearly straight, lobe formed by these margins angular, tip of tail angular to narrowly rounded. Length of dorsal caudal margin 2.50 (2.54–2.89) in precaudal length, preventral caudal margin 2.37 (1.96–2.37) in dorsal caudal margin, terminal lobe from caudal tip to subterminal notch about 3.19 (2.97–3.36) in dorsal caudal margin, subterminal margin length 2.05 (1.89–2.64) in terminal margin.

Counts of total vertebral centra (TC) 148 (146–163), precaudal centra (PC) 74 (71–82), monospondylous precaudal (MP) centra 48 (42–44), diplospondylous precaudal (DP) centra 26 (28–38), diplospondylous caudal (DC) centra 74 (74–81); MP centra 32.4 (27.0–29.5)%, DP centra 17.6 (19.2–23.5)%, and DC centra 50.0 (48.4–51.4)% of TC centra. Ratios of DP/MP centra 0.54 (0.65–0.86), DC/MP centra 1.54 (1.72–1.84). MP-DP transition usually difficult to precisely locate, forming a long`stutter zone' of alternating long and short centra.

Colour. Dorsal surfaces greyish to brownish (bronze hue when fresh), whitish ventrally and on lower sides. Demarcation between darker dorsal and paler ventral colours (waterline) extending from snout to lower margin of eye and through lower edges of gill slits to pectoral-fin base; from pectoral-fin insertion extending almost horizontally to below 1st dorsal-fin base before extending up slightly, then through to caudal peduncle at close to middle of sides; edge of waterline usually very diffuse and poorly defined. First dorsal fin without markings; second dorsal fin with a distinct black blotch which covers most of the fin and often extends slightly onto upper sides of body below second dorsal-fin base, free rear tip usually paler, edges of black blotch diffuse and not well defined; pectoral, pelvic and anal fins sometimes with a paler posterior margin; caudal fin often with whitish apices.

Size. Specimens examined in this study ranged from 370–674 mm TL, all immature. White (2007) recorded males and females ranging in length from 557–862 and 497–710 mm, respectively, from southern Indonesian waters; all males <758 mm TL were juveniles to late-adolescents; all females were immature. Yano et al. (2005) reported mature males between 709 and 823 mm TL, with the largest immature male 710 mm TL, from Malaysia. Thus, males begin to mature around 710 mm TL. Yano et al. (2005) reported two pregnant females of 830 and 846 mm TL, both containing two embryos, with the largest embryo 320 mm TL. Thus birth size is between 320 and 370 mm TL.

Distribution. Specimens examined were collected from Borneo and Indonesia. Reported to occur throughout the Indo –West Pacific from Kenya eastwards to Indonesia and northwards to China ( Compagno et al., 2005), but its distribution west of the Indo –Malay Peninsula needs validating. Capture locations of examined specimens shown in Figure 4 .

Etymology. Pietschmann described this species in 1913 and named it after Alvin Seale (1871–1958), an American ichthyologist who first described this species in 1910 as Carcharias borneensis , which was objectively invalid, being preoccupied by Carcharhinus borneensis ( Bleeker, 1858) .

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 8. Lateral view of Carcharhinus sealei: A. drawing of holotype of Carcharias borneensis (= C. sealei) BSMP 2720 (372 mm TL) from Seale (1910); B. neotype CSIRO H 4919 – 04 (juvenile male 373 mm TL), preserved; C. CSIRO H 7293 – 02 (juvenile male 653 mm TL), fresh.