Carcharhinus humani, White, William T. & Weigmann, Simon, 2014

White, William T. & Weigmann, Simon, 2014, Carcharhinus humani sp. nov., a new whaler shark (Carcharhiniformes: Carcharhinidae) from the western Indian Ocean, Zootaxa 3821 (1), pp. 71-87 : 72-84

Carcharhinus humani sp. nov.

Human’s Whaler Shark

Figs 1–6 ; Tables 1–3

Carcharhinus menisorrah— Wheeler, 1960: 271, fig. 1 ( Tanzania).

Carcharhinus sealei— Bass et al., 1973: 70, fig. 28, pl. 14 (southern Africa); Garrick, 1982: 48, fig. 24 ( South Africa); Smith & Heemstra, 1986: 76, fig. 9.16 (southern Africa); Compagno, 1988: 327 ( Seychelles, LACM-SPA-NSF-21, not found Nov. 2013); Compagno et al, 1989: 68, ill. (southern Africa); Bonfil & Abdallah, 2004: 31 (Red Sea and Gulf of Aden).

Carcharhinus sp. — White, 2012: 2 ( Kuwait).

Carcharhinus tjutjot— D’Aubrey, 1964: 41, pl. 23 ( Natal, South Africa);? Davies & Joubert, 1966: 15 ( South Africa); Smith & Smith (1969): 5, pl. 2H ( Seychelles).

Eulamia dussumieri— Smith, 1949: 42, fig. 8 ( Mozambique).

Holotype. ZMH 26030, adult male 828 mm TL (844 mm TL when fresh), off Socotra Islands, 12°04’48” N, 53°12’36” E – 12°09’12” N, 53°10’6” E, 36–40 m depth, R.V. ‘Vityaz’, cruise 17, station 2829, 15 Jan. 1989 (taken together with a female specimen of 805 mm TL which was not retained).

Paratypes (n=3) Mean Holotype Min. Max.

......continued on the next page Paratypes (n=3) Mean Holotype Min. Max.

......continued on the next page Paratypes (n=3) Mean Holotype Min. Max.

Paratypes. ANSP 25838, female 599 mm TL, Natal, South Africa, 1935; ANSP 55298, female 364 mm TL, Maputo Bay, Mozambique, ~26° S, 32°45’ E, 1922; CSIRO H 6891-01 (jaws only), male 731 mm TL, Fahaheel fish market, Kuwait, 29°05’ N, 48°09’ E, 17 Apr. 2008; ZMH 26031, juvenile male 536 mm TL (545 mm TL when fresh), off Socotra Islands, 12°39’ N, 53°27’ E – 12°36’ N, 53°20’2” E, 41–43 m depth, R.V. ‘Vityaz’, cruise 17, station 2567, 28 Oct. 1988 (taken together with two juvenile male specimens of 627 and 635 mm TL, and two adult male specimens of 768 and 831 mm TL, which were not retained).

Diagnosis. A small species of Carcharhinus with: a moderately long and narrowly rounded snout; upper anterior teeth oblique and blade-like, coarsely serrated, lateral margin deeply notched and with several large, smooth basal cusplets; lower anterior teeth narrower, slightly oblique, lateral margins notched and usually several smooth basal cusplets; total tooth row counts 24–26/22–25, or 46–50; interdorsal space with a weak ridge usually present on midline, 20.4–22.0% TL; first dorsal fin moderately tall and slightly falcate, origin just anterior to pectoral-fin free rear tip, length 13.4–14.6% TL, 1.3–1.5 times height, inner margin 1.7–2.3 times in base; second dorsal fin broadly triangular, height 39–48% of first dorsal-fin height, origin about opposite to anal-fin origin; anal fin falcate, height 0.8–1.0 times second dorsal height, base 0.9–1.2 times second dorsal-fin base; colour pale brownish to grey dorsally, whitish ventrally; second dorsal fin with a black blotch on upper one to two thirds of fin, not extending onto upper surface of body and strongly demarcated from ground colour; most other fins with whitish outer margins; total vertebral counts 153–160 in the four type specimens (152–167 in Bass et al., 1973); precaudal counts 75–79 (74–85 in Bass et al., 1973); monospondylous precaudal counts 45–48; diplospondylous precaudal counts 27–32; diplospondylous caudal counts 78–81.

Description. Body slender, trunk almost pear-shaped in section at first dorsal-fin base, length of trunk from fifth gill slits to vent 1.17 in holotype (1.09–1.18 in the 3 whole paratypes) times head length ( Fig. 2 ); no predorsal or postdorsal ridges; interdorsal ridge weak (absent in one paratype); lateral ridges absent. Caudal peduncle moderately stout, roughly hexagonal in cross-section at second dorsal-fin insertion, postdorsal and postventral spaces flattened and usually with a very shallow median groove, lateral surfaces somewhat rounded to angular; no lateral ridges or keels; height of caudal peduncle at second dorsal-fin insertion 1.06 (1.13–1.44) times its width, 2.45 (1.93–2.55) times in dorsal–caudal space. Precaudal pits prominent; upper pit pronounced, deep, arcuate and crescentic; lower pit smaller but as pronounced.

Head length to fifth gill opening 0.92 (0.90) times in pectoral–pelvic space; head moderately stout, not flattened, ellipsoidal in shape in cross-section at eyes ( Fig. 3 ). Outline of head in lateral view slightly undulated dorsally, medially slightly concave on snout, nearly straight above eye, slightly concave at nape, slightly convex above gills to first dorsal-fin origin; slightly convex ventrally along lower jaws and beneath gills. In dorsoventral view, head anteriorly parabolic. Snout moderately long, preoral snout length 1.05 (1.09–1.16) times mouth width; snout tip narrowly rounded in dorsoventral view and weakly indented anterior to nostrils; snout narrowly rounded in lateral view, slightly convex above and below.

External eye opening of fleshy orbit without anterior or posterior notches. Eyes moderately large, subcircular, height 1.31 (1.20–1.46) times in length, length 11.33 (8.01–9.02) times in head length; situated lateral to very slightly dorsolateral on head, with lower edges sometimes just crossing horizontal head rim in dorsal view. 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 gill slits subequal in height, fifth smallest; fifth slit about 0.81 (0.73–0.94) times height of third; height of third slit 8.37 (7.88–9.03) times in head length, 1.35 (0.89–1.14) times eye length; margins of first four gill slits nearly straight to weakly concave, fifth slightly concave; upper edges of second and third gill slits most elevated, upper ends about level with lower margin of eye. Gill filaments not visible externally in lateral view. Gill-raker papillae absent from gill arches.

Nostrils with moderately large, subcircular incurrent apertures; relatively long, broadly triangular anterior nasal flaps with pointed tips, posterior nasal flaps vestigial, excurrent apertures small and circular; well in front of mouth; width 2.89 (2.33–2.69) times in internarial width, 1.26 (1.30–1.58) times in eye length, 1.63 (1.23–1.40) times in longest gill-opening.

Mouth moderately large, moderately to narrowly arched; width 3.52 (3.36–3.39) times in head length; mouth length 1.39 (1.32–1.67) times 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 for most of their lengths. Labial furrows restricted to mouth corners and barely visible in ventral view. Labial cartilages apparently absent.

Teeth rather few, in 26 (24–26)/24(22–25), or 50 (46–50) total rows. 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=5): upper jaw 12 (12–13) + 1 (1–2) + 13 (11–12), lower jaw 11 (11–12) + 1 (1) + 12 (10–12). Upper anterolateral teeth with moderately broad, strongly 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, coarsest at about one third of its length; lateral margin usually with some coarse to fine serrations; basal cusplets smooth, without serrations (Figs. 4a and 5a). Lower anterolateral teeth with narrower, slightly oblique cusps; lateral margins notched, with several small to large, smooth basal serrae; medial margins convex basally and then concave; both margins smooth distally (Figs. 4b and 5b).

FIGURE 4. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, (A) 6th upper anterolateral tooth on right side, (B) 3rd lower anterolateral tooth on right side. Scale bar: 2 mm.

FIGURE 5. Carcharhinus humani sp. nov., paratype, CSIRO H 6891-01, male 731 mm TL, (A) 4th upper anterolateral tooth on right side, (B) 4th lower anterolateral tooth on right side. Scale bar: 2 mm.

Lateral trunk denticles with flat, rhomboidal crowns, wider than long, closely imbricated; crowns with 5 prominent longitudinal ridges that extend their entire lengths onto the cusps; medial cusp very short but strong, with two pairs of lateral cusps; most lateral pair of cusps much shorter and sometimes barely evident. Denticles absent from insertion of the fins and from dorsal surface and inner sides of the mature claspers of the holotype.

Pectoral fins moderately large, relatively narrow, weakly falcate; anterior margin convex, apices narrowly rounded (slightly more pointed in some paratypes); posterior margin moderately concave; free rear tip subangular, inner margin convex; base broad, about 49 (42–52)% of fin length; length from origin to rear tip 0.73 (0.80–0.85) times anterior margin length; slightly larger in area to first dorsal fin; origin under fifth 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 0.48 (0.44–0.47) of pectoral-fin anterior margins; area slightly larger than that of anal fin; anterior margin nearly straight to weakly convex; apices subangular; posterior margin very weakly concave; free rear tip angular, inner margin nearly straight. Claspers of adult male holotype relatively long, outer length 10.3% of TL, base 5.4 times in outer length.

First dorsal fin moderately tall, moderately falcate; anterior margin slightly convex; apex narrowly rounded; posterior margin slightly concave to nearly straight (excluding free rear tip), angling slightly anteroventrally from apex; free rear tip acutely pointed, inner margin very shallowly concave; origin just anterior to pectoral-fin free rear tip; midpoint of base 1.42 (1.21–1.33) times closer to pelvic origins than pectoral insertions; free rear tip anterior to pelvic-fin origins by about an eye length. First dorsal-fin base 2.05 (2.22–2.27) times in interdorsal space, 2.24 (2.86–3.08) times in dorsal caudal margin; height 1.12 (0.85–0.96) times in base; inner margin 2.04 (1.92–2.41) times in height, 2.29 (1.68–2.20) times in base.

Second dorsal fin small, broadly triangular, very weakly falcate ( Fig. 6 ); height 0.48 (0.39–0.42) times first dorsal-fin height; base 0.63 (0.65–0.73) times first dorsal-fin base; anterior margin slightly convex; apex moderately rounded; posterior margin moderately concave; free rear tip acutely pointed, inner margin nearly straight; origin well behind pelvic-fin free rear tips and slightly anterior (about opposite in some paratypes) to analfin origin; rear tip slightly anterior (slightly posterior in some paratypes) of anal-fin free rear tip, in front of upper caudal-fin origin by 1.03 (0.85–1.29) times its inner margin length; posterior margin curving posteroventrally from apex; insertion slightly anterior to fin apex. Second dorsal-fin base 1.27 (1.17–1.42) times in dorsal–caudal space; height 1.49 (1.39–1.67) times in base; inner margin 0.93 (0.91–1.05) times in height, 1.61 (1.53–1.62) times in base.

Anal fin falcate and apically narrow; height 0.82 (0.91–1.05) times second dorsal-fin height, base length 0.89 (0.97–1.19) times second dorsal-fin base; anterior margin slightly convex; apex moderately rounded; posterior margin deeply concave; free rear tip acutely pointed, inner margin nearly straight; origin almost level with second dorsal-fin origin; insertion about opposite second dorsal-fin insertion, about level with fin apex; free rear tip in front of lower caudal-fin origin by about its inner margin length; posterior margin almost vertical and then abruptly posterodorsally from apex. No preanal ridges obvious. Anal-fin base 1.29 (1.08–1.34) times in anal–caudal space; height 1.62 (1.65–1.82) times in base; inner margin 0.87 (0.95–1.01) times in height, 1.41 (1.56–1.84) times 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 moderately convex, tip of ventral caudalfin lobe angular; upper and lower postventral margins almost straight; subterminal margin nearly straight; terminal margin slightly to moderately concave, lobe formed by these margins subangular, tip of tail narrowly rounded (sometimes pointed). Length of dorsal caudal margin 3.15 (2.53–2.71) times in precaudal length, preventral caudal margin 2.09 (2.24–2.25) times in dorsal caudal margin, terminal lobe from caudal tip to subterminal notch about 3.38 (3.24–3.59) times in dorsal caudal margin, subterminal margin length 2.02 (1.84–1.92) times in terminal margin.

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(upper).

Ρrecªudªˈ centrª

. humani Sp. noV. * 2 2 **. coatesi 1 1 2 3 1 2 1 2 1. dussumieri 1 1 1 3 2 1 1

. sealei 1 1 1 1 2 3 2 1. tjutjot 1 1 2 1 2 2 1 1

Caudal centra

. humani Sp. noV. 3 1. coatesi 1 2 2 1 2 1 2 3

. dussumieri 1 1 2 3 1 1 1 1

. sealei 4 3 3 1 1. tjutjot 1 1 1 1 2 2 1 1 1

Total centra. dussumieri 1 1 2 2 1 1. tjutjot 1 1 1 1 1 1 1 2 1 1

Total centra. humani Sp. noV. * 2 1 1 **. coatesi 1 2 1 2 2 3 1 1 1

. sealei 1 1 2 1 3 2 1 1

Counts of total vertebral centra (TC) 153 (153–160 in other types; 152–167 in Bass et al., 1973), precaudal centra (PC) 75 (75–79 in other types; 74–85 in Bass et al., 1973), monospondylous precaudal (MP) centra 45 (47–48), diplospondylous precaudal (DP) centra 30 (27–32), diplospondylous caudal (DC) centra 78 (78–81); MP centra 29.4 (29.4–31.4)%, DP centra 19.6 (17.6–19.7)%, DC centra 51.0 (49.7–51.0)% of TC. Ratios of DP/MP centra 0.67 (0.56–0.68), DC/MP centra 1.73 (1.62–1.72). Transition between MP and DP centra posterior to pelvic girdle.

Colour. Colour overall similar to other members of the sealei / dussumieri group (see White, 2012). Second dorsal fin with a distinct black apical blotch on upper two thirds of fin (one third of fin in smaller paratypes), strongly demarcated from the rest of the fin (not diffuse-edged), not extending onto upper sides of body below second dorsal-fin base. Pectoral, pelvic and anal fins with paler posterior margin (not evident in some paratypes); caudal fin with white tipped ventral lobe.

Size. Type specimens ranged from 364–828 mm TL. A 536 mm TL male was immature; and an 828 mm TL male was mature. Not retained males of 627 and 635 mm TL, respectively, were immature; and not retained males of 768 and 831 mm TL, respectively, were mature. The 12 specimens (8 males and 4 females) examined by Wheeler (1960, as C. menisorrah ) ranged from 506–855 mm TL, with one 767 mm TL male immature, and the 2 males> 850 mm TL were mature. An unregistered Seychelles specimen from the LACM (not found November 2013, R. Feeney, pers. comm.) referred to by Compagno (1988, p. 327) as C. sealei is likely this species and was a subadult male at 762 mm TL. Bass et al. (1973, as C. sealei ) reported two embryos of 440 and 450 mm TL from an 870 mm TL mature female, the smallest free-swimming specimen 350 mm TL and thus a size at birth of 350–450 mm TL; males and females over 750 mm TL were mature; largest females and males were 920 and 900 mm TL, respectively. Bass et al. (1973) reported 6 pregnant females containing either one or two embryos.

Upper laterals

10 11 12 13 14 Carcharhinus humani sp. nov. 1 6 * 2 Carcharhinus coatesi 3 7

Carcharhinus dussumieri 3 5 Carcharhinus sealei 8 16 8 Carcharhinus tjutjot 5 10 Lower laterals

10 11 12 13 14 15

Carcharhinus humani sp. nov. 1 4 3 *

Carcharhinus coatesi 3 7

Carcharhinus dussumieri 2 2 2 2 Carcharhinus sealei 2 12 16 2 Carcharhinus tjutjot 9 5 2

Distribution. Type specimens ranged from Kuwait in the Persian (Arabian) Gulf, to the Socotra Islands, and south to Maputo Bay in Mozambique and Natal in South Africa. Wheeler (1960) reported this species (as C. menisorrah ) from off Zanzibar in Tanzania as well as an embryo from Lamu in Kenya. Bass et al. (1973) reported this species (as C. sealei ) from off Beira, Bazaruto Island and Maputo Bay (as Delagoa Bay) in Mozambique, off the Natal coast of South Africa, and a single specimen from off the west coast of Madagascar (17°30’ S, 43°05’ E). An image taken by J. Randall (Bishop Museum, Hawai’i) off Bahrain in 1977 is also of this species. The image of C. tjutjot in Smith & Smith (1969) from the Seychelles is also C. humani . They also reported that this species occurs close inshore in depths of less than 40 m, except for the Madagascan specimen which was found on the surface over deep water (1260 m; listed as both 1260 and 1360 m in Bass et al., 1973) but close to shallow water ( Bass et al., 1973). The holotype was caught in 36–40 m depth, paratype ZMH 26031 in 41–43 m depth. A distribution map is shown in Figure 1 .

Etymology. Named after the late Dr Brett Human, who made important contributions to shark taxonomy in South Africa and Oman in the western Indian Ocean region, and who is sorely missed by his colleagues. The recognition expressed by authors also reflects the collective view of a number of other chondrichthyan biologists who had the privilege of working and socialising with Dr Human.

Figures

FIGURE 1. Map of the western Indian Ocean depicting the collection locations of specimens of Carcharhinus humani sp. nov.: holotype (black star), paratypes (black circles), other records (white circles).

FIGURE 2. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, in (A) dorsal, (B) lateral, and (C) ventral views. Scale bar: 5 cm.

FIGURE 3. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, head in (A) dorsal, (B) lateral, and (C) ventral views. Scale bar: 5 cm.

FIGURE 6. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, second dorsal fin in lateral view. Scale bar: 2 cm.