Zootaxa 3821 (1): 071–087 www.mapress.com /zootaxa / Copyright © 2014 Magnolia Press
Article
ISSN 1175-5326 (print edition)
ZOOTAXA
ISSN 1175-5334 (online edition)
http://dx.doi.org/10.11646/zootaxa.3821.1.5 http://zoobank.org/urn:lsid:zoobank.org:pub:57667BFD-A52B-40C1-95DF-1002BB5B54B1
Carcharhinus humani sp. nov., a new whaler shark (Carcharhiniformes: Carcharhinidae) from the western Indian Ocean WILLIAM T. WHITE1,3 & SIMON WEIGMANN2 1
CSIRO Marine and Atmospheric Research, Wealth from Oceans Flagship, GPO Box 1538, Hobart, Tasmania, 7001, Australia University of Hamburg, Biocenter Grindel and Zoological Museum, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany 3 Corresponding author. E-mail: [email protected] 2
Abstract A new species of whaler shark, Carcharhinus humani sp. nov., is described based on five type specimens from the western Indian Ocean near the Socotra Islands, off Kuwait, Mozambique, and South Africa. The new species represents the fifth species of the C. dussumieri/sealei group and the third species of the C. sealei subgroup. The new species is the only species of the C. sealei subgroup known from the western Indian Ocean. Within the C. sealei subgroup, C. humani differs from C. sealei in having a sharply demarcated black apical marking on the second dorsal fin which does not extend onto body surface (vs. black marking diffuse-edged and usually extending onto upper sides of trunk), a longer horizontal prenarial length (4.1–4.7 vs. 3.4–4.2% TL), and a longer preoral length (6.8–7.6 vs. 5.7–6.5% TL); C. humani differs from C. coatesi in having a taller second dorsal fin (its height 4.0–4.5 vs. 2.9–3.6% TL), a shorter first dorsal fin (its length 13.4–14.6 vs. 14.8–17.3% TL), and more vertebrae (total centra 152–167 vs. 134–147). Key words: new species, Carcharhinus dussumieri/sealei group, systematics, description, conservation status.
Introduction Carcharhinus is one of the most species-rich genera of sharks and the most speciose genus within the family Carcharhinidae, with about 34 species currently considered valid nominal species and one undescribed species, Carcharhinus sp. A [sensu Compagno et al., 2005]. Although there has been only one new species described in the last 63 years, i.e. Carcharhinus leiodon Garrick, 1985, several species have been recently resurrected as valid names (see White, 2012). Two of these, Carcharhinus coatesi (Whitley, 1939) and Carcharhinus tjutjot (Bleeker, 1852), belong to the Carcharhinus dussumieri/sealei group, and were previously considered to be junior synonyms of Carcharhinus sealei (Pietschmann, 1913) and Carcharhinus dussumieri (Müller & Henle, 1839), respectively (White, 2012). Species of this group are characterised by the possession of a black-tipped second dorsal fin while all other fins are plain (White, 2012). In the revision of this group by White (2012), the above four species were separated and redescribed as distinct, valid taxa. Two subgroups were identified, the dussumieri subgroup (C. dussumieri and C. tjutjot), and the sealei subgroup (C. coatesi, C. sealei and a possibly undescribed species C. sp.). According to White (2012), species of the sealei subgroup differ from those of the dussumieri subgroup by having a moderately to slightly falcate first dorsal fin at all sizes (vs. first dorsal fin not falcate except in some small juveniles), a non-flattened snout, rounded in dorsoventral view, narrowly rounded in lateral view (vs. snout slightly flattened, slightly pointed in dorsoventral view, narrowly pointed in lateral view), a ratio of pectoral-fin anterior margin / its length of 1.44–1.60 (vs. 1.35–1.48), and a total vertebral count of more than 134 (vs. equal to or less than 138). The possibly undescribed species was based on a record from the Persian (Arabian) Gulf, first identified as C. sealei, and was considered to be possibly conspecific with specimens examined in Wheeler (1960, as C. menisorrah) and Garrick (1982). Recent examination of four western Indian Ocean specimens has confirmed that this represents a new species
Accepted by M. R. de Carvalho: 26 May 2014; published: 19 Jun. 2014
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of Carcharhinus belonging to the sealei subgroup. The new species is herein formally named and described based on five type specimens. The holotype and one of the paratypes were sampled aboard the Russian R.V. ‘Vityaz’ during its 17th cruise in 1988 and 1989. Many other new chondrichthyan taxa and rare species were caught during this cruise, resulting in one of the largest worldwide collections of deep-water chondrichthyans from the western Indian Ocean (Weigmann et al., 2013).
Methods External morphometric measurements were taken by digital vernier calipers to one tenth of a millimetre (mm) from specimens preserved in 70% ethanol. Measurement terminology follows Compagno (1988, 2001) except for total length = TL and additional point-to-point measurements were taken, i.e. PD1 (pre-first-dorsal-fin-length), HDL (head length), PG1 (prebranchial length), POB (preorbital length), PRN (prenarial snout length). The point-to-point measurements are used in the description if not otherwise stated. Dentitional terms follow Compagno (1988, 2001). Vertebral terminology, method of counting and vertebral ratios follow Springer & Garrick (1964) and Compagno (1988, 2001). The holotype (ZMH 26030) and 3 paratypes (ZMH 26031, ANSP 25838 and ANSP 55298) of the new species were measured in full (Table 1). In the descriptions and diagnoses, measurements for the holotype are given first, followed in parantheses by the ranges for the 3 aforementioned paratypes. Meristics were taken from radiographs of these four type specimens. Counts were obtained separately for trunk (monospondylous), precaudal (monospondylous + diplospondylous to origin of upper lobe of caudal fin) and caudal (centra of the caudal fin) vertebrae. Tooth row counts were taken from radiographs of the holotype (ZMH 26030) and one paratype (ZMH 26031), in situ from two specimens (ANSP 25838 and ANSP 55298) and from one set of dried, excised jaws (CSIRO H 6891-01). Comparative morphometric and meristics values were taken from White (2012) for C. coatesi, C. dussumieri, C. sealei and C. tjutjot. Additional tooth row and vertebral counts from Bass et al. (1973) and Garrick (1982) were also included. The catch locations of the type specimens and further records of the new species are shown in the map in Figure 1 which was generated based on the Global Relief Model ETOPO1 by the National Oceanic and Atmospheric Administration (NOAA; Amante & Eakins, 2009). Country borders, lakes, and rivers were visualized by means of the shapefiles supplied by ESRI for the ArcExplorer-Java Edition for Education 2.3.2 (AEJEE). For a map with all stations of cruise 17 of R.V. ‘Vityaz’ see e.g. Weigmann et al. (2013). Type specimens are referred to by the following prefixes for their registration numbers: ANSP, Academy of Natural Sciences, Philadelphia; CSIRO, Australian National Fish Collection, Hobart; ZMH, Zoological Museum, Hamburg, Germany.
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).
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TABLE 1. Proportional dimensions as percentages of total length for the holotype of Carcharhinus humani (ZMH 26030), and ranges for the 3 measured paratypes. Means for all four type specimens are also included. Paratypes (n=3)
Mean
Holotype
Min.
Max.
TL, total length (mm)
828
364
599
581.8
PRC, precaudal length
75.7
71.4
72.8
73.1
PD2, pre-second dorsal length
62.1
57.4
57.9
58.8
PD1, pre-first dorsal length
29.5
28.2
30.6
29.4
PD1 (horiz.), pre-first dorsal length (horizontal)
29.0
28.0
29.3
28.7
HDL, head length
22.9
21.3
22.2
22.1
HDL (horiz.), head length (horizontal)
22.0
20.2
22.1
21.5
PG1, prebranchial length
18.3
17.3
17.8
17.7
PG1 (horiz.), prebranchial length (horizontal)
17.5
16.4
17.6
17.0
POB, preorbital length
8.2
7.8
8.9
8.2
POB (horiz.), preorbital length (horizontal)
6.9
6.3
7.5
6.9
POR, preoral length
6.8
6.8
7.6
7.2
PRN, prenarial length
5.0
4.8
5.4
5.1
PRN (horiz.), prenarial length (horizontal)
4.2
4.1
4.7
4.4
PP1, prepectoral length
21.8
20.5
21.7
21.3
PP2, prepelvic length
47.3
44.4
44.8
45.3
SVL, snout-vent length
49.8
46.3
46.3
47.5
PAL, preanal length
62.6
57.1
57.6
58.7
IDS, interdorsal space
22.0
20.4
21.3
21.0
DCS, dorsal-caudal space
8.6
7.9
8.9
8.4
PPS, pectoral-pelvic space
21.0
19.1
20.1
20.0
PAS, pelvic-anal space
8.5
7.5
8.1
8.0
ACS, anal-caudal space
7.8
7.0
8.8
7.8
EYL, eye length
2.0
2.4
2.8
2.5
EYH, eye height
1.5
1.9
2.0
1.9
INO, interorbital space
8.8
9.2
9.6
9.3
NOW, nostril width
1.6
1.7
2.1
1.8
INW, internarial space
4.6
4.5
4.9
4.7
ANF, anterior nasal flap length
0.5
0.5
0.8
0.6
MOL, mouth length
4.7
3.9
5.0
4.5
MOW, mouth width
6.5
6.3
6.6
6.5
ULA, upper labial furrow length
0.3
0.4
0.6
0.5
LLA, lower labial furrow length
0.0
0.0
0.4
0.2
GS1, first gill slit height
2.5
2.4
2.5
2.5
GS2, second gill slit height
2.8
2.3
2.7
2.6
GS3, third gill slit height
2.7
2.4
2.7
2.6
GS4, fourth gill slit height
2.6
2.4
2.6
2.5
GS5, fifth gill slit height
2.2
2.0
2.3
2.1
ING, intergill
4.8
4.2
4.8
4.6
HDH, head height
10.7
9.4
10.8
10.1
......continued on the next page
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TABLE 1. (Continued) Paratypes (n=3)
Mean
Holotype
Min.
Max.
TRH, trunk height
12.8
11.0
11.1
11.5
ABH, abdomen height
12.2
9.8
11.7
11.0
TAH, tail height
7.4
7.5
8.3
7.9
CPH, caudal peduncle height
3.5
3.5
4.1
3.7
HDW, head width
11.2
10.2
11.5
11.0
TRW, trunk width
11.4
8.5
11.1
10.4
ABW, abdomen width
9.8
7.3
10.4
9.3
TAW, tail width
7.8
6.0
7.3
7.1
CPW, caudal peduncle width
3.3
2.8
3.2
3.1
P1L, pectoral length
10.4
9.9
11.0
10.5
P1A, pectoral anterior margin
14.3
14.7
16.6
15.5
P1B, pectoral base
5.1
4.6
5.6
5.0
P1H, pectoral height
13.3
13.7
13.9
13.7
P1I, pectoral inner margin
5.9
5.3
6.7
6.0
P1P, pectoral posterior margin
11.3
10.6
11.8
11.1
P2L, pelvic length
9.1
8.4
9.1
8.8
P2A, pelvic anterior margin
7.0
7.0
7.5
7.2
P2B, pelvic base
6.3
5.2
6.0
5.7
P2H, pelvic height
5.8
4.8
5.3
5.3
P2I, pelvic inner margin
3.0
3.0
4.0
3.3
P2P, pelvic posterior margin
4.9
4.7
5.6
5.1
CLO, clasper outer length
10.3
–
–
–
CLI, clasper inner length
10.9
–
–
–
CLB, clasper base width
1.9
–
–
–
D1L, first dorsal length
14.6
13.4
13.5
13.8
D1A, first dorsal anterior margin
14.7
16.0
16.9
15.9
D1B, first dorsal base
10.7
9.0
9.4
9.6
D1H, first dorsal height
9.6
9.6
10.5
10.0
D1I, first dorsal inner margin
4.7
4.3
5.3
4.8
D1P, first dorsal posterior margin
9.8
8.5
11.3
9.9
D2L, second dorsal length
10.7
9.2
10.4
10.1
D2A, second dorsal Anterior margin
7.3
7.5
8.7
7.8
D2B, second dorsal base
6.8
5.9
6.7
6.4
D2H, second dorsal height
4.5
4.0
4.2
4.2
D2I, second dorsal inner margin
4.2
3.8
4.3
4.1
D2P, second dorsal posterior margin
5.9
4.6
5.2
5.2
ANL, anal length
10.1
10.1
10.8
10.4
ANA, anal anterior margin
7.1
7.2
7.9
7.5
ANB, anal base
6.1
6.5
7.0
6.5
ANH, anal height
3.7
3.7
4.0
3.8
ANI, anal inner margin
4.3
3.8
4.2
4.0
......continued on the next page
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TABLE 1. (Continued) Paratypes (n=3) ANP, anal posterior margin
Holotype
Min.
Max.
4.8
4.9
5.2
Mean 5.0
CDM, dorsal caudal margin
24.1
26.9
28.2
26.7
CPV, preventral caudal margin
11.5
12.0
12.6
12.1
CPL, lower postventral caudal margin
5.3
4.3
4.8
4.8
CPU, upper postventral caudal margin
12.4
12.6
14.5
13.4
CFW, caudal fork width
6.7
6.4
7.0
6.7
CFL, caudal fork length
7.4
8.3
9.0
8.4
CST, subterminal caudal margin
2.8
3.1
3.5
3.2
CTR, terminal caudal margin
5.6
5.9
6.5
6.1
CTL, terminal caudal lobe
7.1
7.5
8.7
7.9
DAO, second dorsal origin-anal origin
1.8
0.3
1.0
0.9
DAI, second dorsal insertion-anal insertion
1.0
0.3
0.6
0.6
DPI, D1 midpoint - pectoral insertion
8.3
8.6
9.1
8.7
DPO, D1 midpoint - pelvic origin
11.8
10.6
11.6
11.4
PDI, pelvic midpoint - D1 insertion
10.6
9.9
10.1
10.2
PDO, pelvic midpoint - D2 origin
10.5
9.6
10.7
10.2
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).
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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.
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
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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).
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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.
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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 CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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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.
FIGURE 6. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, second dorsal fin in lateral view. Scale bar: 2 cm.
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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FIGURE 7. Lateral view of: (A) Carcharhinus coatesi (CSIRO H 6582-05, female 728 mm TL), (B) Carcharhinus dussumieri (not retained, adult male ~800 mm TL), s(C) Carcharhinus sealei (CSIRO H 7293-02, juvenile male 653 mm TL), (D) Carcharhinus tjutjot (CSIRO H 7293-07). CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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57
55
54
1
113
134
C. humani sp. nov. C. coatesi 1 C. sealei
135
Total centra
1
114
Total centra
C. humani sp. nov. C. coatesi C. dussumieri C. sealei C. tjutjot 1
55
Caudal centra
2
58
2
1
1
1
116
57
59
137
56
115
136
C. dussumieri C. tjutjot
56
1
1
1 2
2
2
1
2
2
3
1
1
1
1
139
58
117
138
60 59 140
118
61 60 141
119
62 61
2
1
2
1
121 142
120
63 62
64 63 122 143
1
1
65 1 3
64 1
123 144
1
3
66 1
1
65 2 1
2 1
1 1
1
2
1
1
145
124
67 66 146
1
1
1
126 147
125
68 67
69 68 127 148
2
69
1
1
1 1
2
1
2
2
2
2 1
1 1
149
128
71 70
70 3 1
1
1
1
*
3
1
*
3
2
130 150
129
72 71
73 72 131
2 1
2 2
4
1
1
3
2
3
3
2
2
3
2
1
1
1
133 154
1 1
134 155
1 2
135 156
74
152
75 74
76 75
77 76
78 77 136
C. humani sp. nov. C. coatesi C. dussumieri C. sealei C. tjutjot 1
1
1
1
1
1
1
82 161
1
83 162
WƌĞĐĂƵĚĂůĐĞŶƚƌĂ **
**
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157
73 132 153
151
138
78 137 158
80 79 159
81 80 160
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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. TABLE 3. Tooth counts for each of the species belonging to the dussumieri-sealei complex examined in this study or from Garrick (1982) and White (2012). Note that counts for both the upper and lower laterals do not include symphysial teeth, and include both the left and right side counts from each jaw. An * denotes the most common count recorded by Bass et al. (1973) from 23 South African specimens of the new species. Upper laterals 10
11
12
13
Carcharhinus humani sp. nov.
1
6*
2
Carcharhinus coatesi
3
7
Carcharhinus dussumieri
3
Carcharhinus sealei
8
Carcharhinus tjutjot
16
8
5
10 13
14
5
Lower laterals 10
11
12
1
4
3*
Carcharhinus coatesi
3
7
Carcharhinus dussumieri
2
2
2
12
16
2
9
5
Carcharhinus humani sp. nov.
Carcharhinus sealei Carcharhinus tjutjot
2
14
15
2 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 CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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(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.
Discussion Carcharhinus humani sp. nov. belongs to the sealei-dussumieri group of whaler sharks, comprised of 4 other species: C. coatesi, C. dussumieri, C. sealei and C. tjutjot. This group was previously considered to consist of only two species, C. dussumieri and C. sealei, but following a revision by White (2012), two additional species names were resurrected as valid, i.e. C. coatesi and C. tjutjot. The new species was mentioned in White (2012) as C. sp., a possibly undescribed species which was previously considered to be conspecific with C. sealei from the western Indian Ocean. The sealei complex has also likely been commonly confused with C. dussumieri throughout its range, particularly in the Arabian Sea region. For example, a number of specimens from Pakistan in the LACM fish collection were identified as C. sealei but images and radiographs of these specimens revealed they were in fact C. dussumieri. Wheeler (1960) provided the first detailed information about this species from the western Indian Ocean as C. menisorrah. The name C. menisorrah has had a complicated history and has been used for C. dussumieri as well as this new species. This was resolved by Garrick (1982) who reported that the type series of C. menisorrah consists of two different species. Although two of the syntypes of C. menisorrah (RMNH 2521 and 2523) are conspecific with C. sealei, Garrick (1982) selected the syntype synonymous with C. falciformis as its lectotype (ZMB 4476). Thus, C. menisorrah is considered a junior synonym of C. falciformis and not C. sealei. Carcharhinus humani can be readily distinguished from C. dussumieri and C. tjutjot in having smooth basal cusplets on upper anterolateral teeth (vs. coarsely serrated basal cusplets), first dorsal fin apically narrow and falcate (vs. broadly triangular and not falcate), and more vertebrae (total centra 152–167 vs. 113–138, precaudal centra 74–85 vs. 55–70). Based on these characters, the new species belongs to the sealei subgroup as defined by White (2012). In White (2012), it was shown that barcoding analyses using the CO1 gene separated all 5 species in this group. Interestingly, C. humani (based on a tissue sample from CSIRO H 6891-01) was closer to C. dussumieri and C. tjutjot (~3% divergent) than to C. sealei and C. coatesi (~7% divergent) which are morphologically more similar. A molecular phylogenetic analysis of this subgroup would be of particular interest to determine the possible origins of this group. A Carcharhinus specimen from the Gulf of Thailand, previously identified as C. dussumieri by Weigmann (2012), was found to be C. tjutjot. This specimen represents the first verified record of C. tjutjot from off Thailand and extends the known distribution of the species to include the Gulf of Thailand. As mentioned above, C. humani has been previously confused with C. sealei in the Western Indian Ocean. In Garrick’s (1982) revision of the genus Carcharhinus, he noted that Western Pacific and Western Indian Ocean specimens of C. sealei differed in a number of characters and stated that they could be treated as separate species or subspecies. His reluctance to consider the Western Indian Ocean population as a distinct species was due to the lack of specimens between these locations and he concluded that these differences could just represent the end segments of a continuous distribution; a justifiable position to take with the data available. However, as discussed by White (2012), there are no validated records of C. sealei from west of the Indo–Malay Archipelago. The characters which Garrick (1982) reported to differ between the Western Indian and Western Pacific populations are: higher second dorsal fin, longer prenarial and preoral lengths, typically smooth-backed (vs. low interdorsal ridge present), and anterior margin of eye located slightly anterior to front of mouth (vs. slightly posterior). In this study, the new Western Indian Ocean species was found to usually possess a weak interdorsal ridge, while most C. sealei examined lacked an interdorsal ridge. The longer prenarial and preoral lengths and higher second dorsal fin appear to be the best morphological characters to separate C. humani from C. sealei: horizontal prenarial length 4.1–4.7 vs. 3.4–4.2% TL, snout tip to inner nostril 4.8–5.4 vs. 3.9–4.7% TL, preoral length 6.8–7.6 vs. 5.7–6.5% TL, second dorsal-fin height 4.0–4.5 vs. 2.8–3.8% TL, 39.3–47.6 vs. 30.9–37.3% of first dorsal-fin height.
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A number of other characters were found to be useful in separating C. humani and C. sealei, in particular the coloration of the second dorsal fin. In C. sealei, the black apical marking on the second dorsal fin covers the majority of the fin, usually extends slightly onto the dorsal surface of the body and its lower edge is diffuse. In contrast, in the new species, the black marking is restricted to the upper one or two thirds of the fin, does not extend onto body surface, and is sharply demarcated from paler fin colour. This character is considered to be particularly useful in separating these two species if based on fresh or recently preserved material. Other morphological characters which were found to differ between C. humani and C. sealei are: longer pre-first dorsal length (28.2–30.6 vs. 26.3–27.6% TL); shorter first dorsal fin (its length 13.4–14.6 vs. 14.7–16.0% TL, 2.0–2.3 vs. 1.7–1.9 in pre-first dorsal length); pelvic-fin anterior margin/pectoral-fin anterior margin ratio (0.45–0.49 vs. 0.38–0.44); and a slightly more slender tail (its height 7.4–8.3 vs. 8.8–9.9% TL). The new species is also similar morphologically to C. coatesi from northern Australia and New Guinea. The black apical markings in both of these species are similar in being strongly demarcated from the paler region of the fin and not extending onto the dorsal surface of the body. Carcharhinus humani is most readily distinguished from C. coatesi in having more vertebrae (total centra 152–167 vs. 134–147; precaudal centra 74–85 vs. 67–76) and in structure of the CO1 gene (~7% divergent). The new species can also be distinguished from C. coatesi in having a taller second dorsal fin (its height 4.0–4.5 vs. 2.9–3.6% TL) and shorter first dorsal fin (its length 13.4–14.6 vs. 14.8–17.3% TL, 3.2–3.3 vs. 4.1–5.6 times second dorsal-fin height).
Key to species of the dussumieri-sealei group 1. 2. 3. 4. -
First dorsal fin moderately to slightly falcate at all sizes; snout not flattened, rounded in dorsoventral view, narrowly rounded in lateral view; total vertebrae >134 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 First dorsal fin not falcate (except in some small juveniles); snout slightly flattened, slightly pointed in dorsoventral view, narrowly pointed in lateral view; total vertebrae
Article
ISSN 1175-5326 (print edition)
ZOOTAXA
ISSN 1175-5334 (online edition)
http://dx.doi.org/10.11646/zootaxa.3821.1.5 http://zoobank.org/urn:lsid:zoobank.org:pub:57667BFD-A52B-40C1-95DF-1002BB5B54B1
Carcharhinus humani sp. nov., a new whaler shark (Carcharhiniformes: Carcharhinidae) from the western Indian Ocean WILLIAM T. WHITE1,3 & SIMON WEIGMANN2 1
CSIRO Marine and Atmospheric Research, Wealth from Oceans Flagship, GPO Box 1538, Hobart, Tasmania, 7001, Australia University of Hamburg, Biocenter Grindel and Zoological Museum, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany 3 Corresponding author. E-mail: [email protected] 2
Abstract A new species of whaler shark, Carcharhinus humani sp. nov., is described based on five type specimens from the western Indian Ocean near the Socotra Islands, off Kuwait, Mozambique, and South Africa. The new species represents the fifth species of the C. dussumieri/sealei group and the third species of the C. sealei subgroup. The new species is the only species of the C. sealei subgroup known from the western Indian Ocean. Within the C. sealei subgroup, C. humani differs from C. sealei in having a sharply demarcated black apical marking on the second dorsal fin which does not extend onto body surface (vs. black marking diffuse-edged and usually extending onto upper sides of trunk), a longer horizontal prenarial length (4.1–4.7 vs. 3.4–4.2% TL), and a longer preoral length (6.8–7.6 vs. 5.7–6.5% TL); C. humani differs from C. coatesi in having a taller second dorsal fin (its height 4.0–4.5 vs. 2.9–3.6% TL), a shorter first dorsal fin (its length 13.4–14.6 vs. 14.8–17.3% TL), and more vertebrae (total centra 152–167 vs. 134–147). Key words: new species, Carcharhinus dussumieri/sealei group, systematics, description, conservation status.
Introduction Carcharhinus is one of the most species-rich genera of sharks and the most speciose genus within the family Carcharhinidae, with about 34 species currently considered valid nominal species and one undescribed species, Carcharhinus sp. A [sensu Compagno et al., 2005]. Although there has been only one new species described in the last 63 years, i.e. Carcharhinus leiodon Garrick, 1985, several species have been recently resurrected as valid names (see White, 2012). Two of these, Carcharhinus coatesi (Whitley, 1939) and Carcharhinus tjutjot (Bleeker, 1852), belong to the Carcharhinus dussumieri/sealei group, and were previously considered to be junior synonyms of Carcharhinus sealei (Pietschmann, 1913) and Carcharhinus dussumieri (Müller & Henle, 1839), respectively (White, 2012). Species of this group are characterised by the possession of a black-tipped second dorsal fin while all other fins are plain (White, 2012). In the revision of this group by White (2012), the above four species were separated and redescribed as distinct, valid taxa. Two subgroups were identified, the dussumieri subgroup (C. dussumieri and C. tjutjot), and the sealei subgroup (C. coatesi, C. sealei and a possibly undescribed species C. sp.). According to White (2012), species of the sealei subgroup differ from those of the dussumieri subgroup by having a moderately to slightly falcate first dorsal fin at all sizes (vs. first dorsal fin not falcate except in some small juveniles), a non-flattened snout, rounded in dorsoventral view, narrowly rounded in lateral view (vs. snout slightly flattened, slightly pointed in dorsoventral view, narrowly pointed in lateral view), a ratio of pectoral-fin anterior margin / its length of 1.44–1.60 (vs. 1.35–1.48), and a total vertebral count of more than 134 (vs. equal to or less than 138). The possibly undescribed species was based on a record from the Persian (Arabian) Gulf, first identified as C. sealei, and was considered to be possibly conspecific with specimens examined in Wheeler (1960, as C. menisorrah) and Garrick (1982). Recent examination of four western Indian Ocean specimens has confirmed that this represents a new species
Accepted by M. R. de Carvalho: 26 May 2014; published: 19 Jun. 2014
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of Carcharhinus belonging to the sealei subgroup. The new species is herein formally named and described based on five type specimens. The holotype and one of the paratypes were sampled aboard the Russian R.V. ‘Vityaz’ during its 17th cruise in 1988 and 1989. Many other new chondrichthyan taxa and rare species were caught during this cruise, resulting in one of the largest worldwide collections of deep-water chondrichthyans from the western Indian Ocean (Weigmann et al., 2013).
Methods External morphometric measurements were taken by digital vernier calipers to one tenth of a millimetre (mm) from specimens preserved in 70% ethanol. Measurement terminology follows Compagno (1988, 2001) except for total length = TL and additional point-to-point measurements were taken, i.e. PD1 (pre-first-dorsal-fin-length), HDL (head length), PG1 (prebranchial length), POB (preorbital length), PRN (prenarial snout length). The point-to-point measurements are used in the description if not otherwise stated. Dentitional terms follow Compagno (1988, 2001). Vertebral terminology, method of counting and vertebral ratios follow Springer & Garrick (1964) and Compagno (1988, 2001). The holotype (ZMH 26030) and 3 paratypes (ZMH 26031, ANSP 25838 and ANSP 55298) of the new species were measured in full (Table 1). In the descriptions and diagnoses, measurements for the holotype are given first, followed in parantheses by the ranges for the 3 aforementioned paratypes. Meristics were taken from radiographs of these four type specimens. Counts were obtained separately for trunk (monospondylous), precaudal (monospondylous + diplospondylous to origin of upper lobe of caudal fin) and caudal (centra of the caudal fin) vertebrae. Tooth row counts were taken from radiographs of the holotype (ZMH 26030) and one paratype (ZMH 26031), in situ from two specimens (ANSP 25838 and ANSP 55298) and from one set of dried, excised jaws (CSIRO H 6891-01). Comparative morphometric and meristics values were taken from White (2012) for C. coatesi, C. dussumieri, C. sealei and C. tjutjot. Additional tooth row and vertebral counts from Bass et al. (1973) and Garrick (1982) were also included. The catch locations of the type specimens and further records of the new species are shown in the map in Figure 1 which was generated based on the Global Relief Model ETOPO1 by the National Oceanic and Atmospheric Administration (NOAA; Amante & Eakins, 2009). Country borders, lakes, and rivers were visualized by means of the shapefiles supplied by ESRI for the ArcExplorer-Java Edition for Education 2.3.2 (AEJEE). For a map with all stations of cruise 17 of R.V. ‘Vityaz’ see e.g. Weigmann et al. (2013). Type specimens are referred to by the following prefixes for their registration numbers: ANSP, Academy of Natural Sciences, Philadelphia; CSIRO, Australian National Fish Collection, Hobart; ZMH, Zoological Museum, Hamburg, Germany.
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).
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TABLE 1. Proportional dimensions as percentages of total length for the holotype of Carcharhinus humani (ZMH 26030), and ranges for the 3 measured paratypes. Means for all four type specimens are also included. Paratypes (n=3)
Mean
Holotype
Min.
Max.
TL, total length (mm)
828
364
599
581.8
PRC, precaudal length
75.7
71.4
72.8
73.1
PD2, pre-second dorsal length
62.1
57.4
57.9
58.8
PD1, pre-first dorsal length
29.5
28.2
30.6
29.4
PD1 (horiz.), pre-first dorsal length (horizontal)
29.0
28.0
29.3
28.7
HDL, head length
22.9
21.3
22.2
22.1
HDL (horiz.), head length (horizontal)
22.0
20.2
22.1
21.5
PG1, prebranchial length
18.3
17.3
17.8
17.7
PG1 (horiz.), prebranchial length (horizontal)
17.5
16.4
17.6
17.0
POB, preorbital length
8.2
7.8
8.9
8.2
POB (horiz.), preorbital length (horizontal)
6.9
6.3
7.5
6.9
POR, preoral length
6.8
6.8
7.6
7.2
PRN, prenarial length
5.0
4.8
5.4
5.1
PRN (horiz.), prenarial length (horizontal)
4.2
4.1
4.7
4.4
PP1, prepectoral length
21.8
20.5
21.7
21.3
PP2, prepelvic length
47.3
44.4
44.8
45.3
SVL, snout-vent length
49.8
46.3
46.3
47.5
PAL, preanal length
62.6
57.1
57.6
58.7
IDS, interdorsal space
22.0
20.4
21.3
21.0
DCS, dorsal-caudal space
8.6
7.9
8.9
8.4
PPS, pectoral-pelvic space
21.0
19.1
20.1
20.0
PAS, pelvic-anal space
8.5
7.5
8.1
8.0
ACS, anal-caudal space
7.8
7.0
8.8
7.8
EYL, eye length
2.0
2.4
2.8
2.5
EYH, eye height
1.5
1.9
2.0
1.9
INO, interorbital space
8.8
9.2
9.6
9.3
NOW, nostril width
1.6
1.7
2.1
1.8
INW, internarial space
4.6
4.5
4.9
4.7
ANF, anterior nasal flap length
0.5
0.5
0.8
0.6
MOL, mouth length
4.7
3.9
5.0
4.5
MOW, mouth width
6.5
6.3
6.6
6.5
ULA, upper labial furrow length
0.3
0.4
0.6
0.5
LLA, lower labial furrow length
0.0
0.0
0.4
0.2
GS1, first gill slit height
2.5
2.4
2.5
2.5
GS2, second gill slit height
2.8
2.3
2.7
2.6
GS3, third gill slit height
2.7
2.4
2.7
2.6
GS4, fourth gill slit height
2.6
2.4
2.6
2.5
GS5, fifth gill slit height
2.2
2.0
2.3
2.1
ING, intergill
4.8
4.2
4.8
4.6
HDH, head height
10.7
9.4
10.8
10.1
......continued on the next page
CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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TABLE 1. (Continued) Paratypes (n=3)
Mean
Holotype
Min.
Max.
TRH, trunk height
12.8
11.0
11.1
11.5
ABH, abdomen height
12.2
9.8
11.7
11.0
TAH, tail height
7.4
7.5
8.3
7.9
CPH, caudal peduncle height
3.5
3.5
4.1
3.7
HDW, head width
11.2
10.2
11.5
11.0
TRW, trunk width
11.4
8.5
11.1
10.4
ABW, abdomen width
9.8
7.3
10.4
9.3
TAW, tail width
7.8
6.0
7.3
7.1
CPW, caudal peduncle width
3.3
2.8
3.2
3.1
P1L, pectoral length
10.4
9.9
11.0
10.5
P1A, pectoral anterior margin
14.3
14.7
16.6
15.5
P1B, pectoral base
5.1
4.6
5.6
5.0
P1H, pectoral height
13.3
13.7
13.9
13.7
P1I, pectoral inner margin
5.9
5.3
6.7
6.0
P1P, pectoral posterior margin
11.3
10.6
11.8
11.1
P2L, pelvic length
9.1
8.4
9.1
8.8
P2A, pelvic anterior margin
7.0
7.0
7.5
7.2
P2B, pelvic base
6.3
5.2
6.0
5.7
P2H, pelvic height
5.8
4.8
5.3
5.3
P2I, pelvic inner margin
3.0
3.0
4.0
3.3
P2P, pelvic posterior margin
4.9
4.7
5.6
5.1
CLO, clasper outer length
10.3
–
–
–
CLI, clasper inner length
10.9
–
–
–
CLB, clasper base width
1.9
–
–
–
D1L, first dorsal length
14.6
13.4
13.5
13.8
D1A, first dorsal anterior margin
14.7
16.0
16.9
15.9
D1B, first dorsal base
10.7
9.0
9.4
9.6
D1H, first dorsal height
9.6
9.6
10.5
10.0
D1I, first dorsal inner margin
4.7
4.3
5.3
4.8
D1P, first dorsal posterior margin
9.8
8.5
11.3
9.9
D2L, second dorsal length
10.7
9.2
10.4
10.1
D2A, second dorsal Anterior margin
7.3
7.5
8.7
7.8
D2B, second dorsal base
6.8
5.9
6.7
6.4
D2H, second dorsal height
4.5
4.0
4.2
4.2
D2I, second dorsal inner margin
4.2
3.8
4.3
4.1
D2P, second dorsal posterior margin
5.9
4.6
5.2
5.2
ANL, anal length
10.1
10.1
10.8
10.4
ANA, anal anterior margin
7.1
7.2
7.9
7.5
ANB, anal base
6.1
6.5
7.0
6.5
ANH, anal height
3.7
3.7
4.0
3.8
ANI, anal inner margin
4.3
3.8
4.2
4.0
......continued on the next page
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TABLE 1. (Continued) Paratypes (n=3) ANP, anal posterior margin
Holotype
Min.
Max.
4.8
4.9
5.2
Mean 5.0
CDM, dorsal caudal margin
24.1
26.9
28.2
26.7
CPV, preventral caudal margin
11.5
12.0
12.6
12.1
CPL, lower postventral caudal margin
5.3
4.3
4.8
4.8
CPU, upper postventral caudal margin
12.4
12.6
14.5
13.4
CFW, caudal fork width
6.7
6.4
7.0
6.7
CFL, caudal fork length
7.4
8.3
9.0
8.4
CST, subterminal caudal margin
2.8
3.1
3.5
3.2
CTR, terminal caudal margin
5.6
5.9
6.5
6.1
CTL, terminal caudal lobe
7.1
7.5
8.7
7.9
DAO, second dorsal origin-anal origin
1.8
0.3
1.0
0.9
DAI, second dorsal insertion-anal insertion
1.0
0.3
0.6
0.6
DPI, D1 midpoint - pectoral insertion
8.3
8.6
9.1
8.7
DPO, D1 midpoint - pelvic origin
11.8
10.6
11.6
11.4
PDI, pelvic midpoint - D1 insertion
10.6
9.9
10.1
10.2
PDO, pelvic midpoint - D2 origin
10.5
9.6
10.7
10.2
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).
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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.
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
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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).
CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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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.
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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 CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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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.
FIGURE 6. Carcharhinus humani sp. nov., holotype, ZMH 26030, adult male 828 mm TL, second dorsal fin in lateral view. Scale bar: 2 cm.
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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FIGURE 7. Lateral view of: (A) Carcharhinus coatesi (CSIRO H 6582-05, female 728 mm TL), (B) Carcharhinus dussumieri (not retained, adult male ~800 mm TL), s(C) Carcharhinus sealei (CSIRO H 7293-02, juvenile male 653 mm TL), (D) Carcharhinus tjutjot (CSIRO H 7293-07). CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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57
55
54
1
113
134
C. humani sp. nov. C. coatesi 1 C. sealei
135
Total centra
1
114
Total centra
C. humani sp. nov. C. coatesi C. dussumieri C. sealei C. tjutjot 1
55
Caudal centra
2
58
2
1
1
1
116
57
59
137
56
115
136
C. dussumieri C. tjutjot
56
1
1
1 2
2
2
1
2
2
3
1
1
1
1
139
58
117
138
60 59 140
118
61 60 141
119
62 61
2
1
2
1
121 142
120
63 62
64 63 122 143
1
1
65 1 3
64 1
123 144
1
3
66 1
1
65 2 1
2 1
1 1
1
2
1
1
145
124
67 66 146
1
1
1
126 147
125
68 67
69 68 127 148
2
69
1
1
1 1
2
1
2
2
2
2 1
1 1
149
128
71 70
70 3 1
1
1
1
*
3
1
*
3
2
130 150
129
72 71
73 72 131
2 1
2 2
4
1
1
3
2
3
3
2
2
3
2
1
1
1
133 154
1 1
134 155
1 2
135 156
74
152
75 74
76 75
77 76
78 77 136
C. humani sp. nov. C. coatesi C. dussumieri C. sealei C. tjutjot 1
1
1
1
1
1
1
82 161
1
83 162
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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. TABLE 3. Tooth counts for each of the species belonging to the dussumieri-sealei complex examined in this study or from Garrick (1982) and White (2012). Note that counts for both the upper and lower laterals do not include symphysial teeth, and include both the left and right side counts from each jaw. An * denotes the most common count recorded by Bass et al. (1973) from 23 South African specimens of the new species. Upper laterals 10
11
12
13
Carcharhinus humani sp. nov.
1
6*
2
Carcharhinus coatesi
3
7
Carcharhinus dussumieri
3
Carcharhinus sealei
8
Carcharhinus tjutjot
16
8
5
10 13
14
5
Lower laterals 10
11
12
1
4
3*
Carcharhinus coatesi
3
7
Carcharhinus dussumieri
2
2
2
12
16
2
9
5
Carcharhinus humani sp. nov.
Carcharhinus sealei Carcharhinus tjutjot
2
14
15
2 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 CARCHARHINUS HUMANI, A NEW SHARK SPECIES
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(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.
Discussion Carcharhinus humani sp. nov. belongs to the sealei-dussumieri group of whaler sharks, comprised of 4 other species: C. coatesi, C. dussumieri, C. sealei and C. tjutjot. This group was previously considered to consist of only two species, C. dussumieri and C. sealei, but following a revision by White (2012), two additional species names were resurrected as valid, i.e. C. coatesi and C. tjutjot. The new species was mentioned in White (2012) as C. sp., a possibly undescribed species which was previously considered to be conspecific with C. sealei from the western Indian Ocean. The sealei complex has also likely been commonly confused with C. dussumieri throughout its range, particularly in the Arabian Sea region. For example, a number of specimens from Pakistan in the LACM fish collection were identified as C. sealei but images and radiographs of these specimens revealed they were in fact C. dussumieri. Wheeler (1960) provided the first detailed information about this species from the western Indian Ocean as C. menisorrah. The name C. menisorrah has had a complicated history and has been used for C. dussumieri as well as this new species. This was resolved by Garrick (1982) who reported that the type series of C. menisorrah consists of two different species. Although two of the syntypes of C. menisorrah (RMNH 2521 and 2523) are conspecific with C. sealei, Garrick (1982) selected the syntype synonymous with C. falciformis as its lectotype (ZMB 4476). Thus, C. menisorrah is considered a junior synonym of C. falciformis and not C. sealei. Carcharhinus humani can be readily distinguished from C. dussumieri and C. tjutjot in having smooth basal cusplets on upper anterolateral teeth (vs. coarsely serrated basal cusplets), first dorsal fin apically narrow and falcate (vs. broadly triangular and not falcate), and more vertebrae (total centra 152–167 vs. 113–138, precaudal centra 74–85 vs. 55–70). Based on these characters, the new species belongs to the sealei subgroup as defined by White (2012). In White (2012), it was shown that barcoding analyses using the CO1 gene separated all 5 species in this group. Interestingly, C. humani (based on a tissue sample from CSIRO H 6891-01) was closer to C. dussumieri and C. tjutjot (~3% divergent) than to C. sealei and C. coatesi (~7% divergent) which are morphologically more similar. A molecular phylogenetic analysis of this subgroup would be of particular interest to determine the possible origins of this group. A Carcharhinus specimen from the Gulf of Thailand, previously identified as C. dussumieri by Weigmann (2012), was found to be C. tjutjot. This specimen represents the first verified record of C. tjutjot from off Thailand and extends the known distribution of the species to include the Gulf of Thailand. As mentioned above, C. humani has been previously confused with C. sealei in the Western Indian Ocean. In Garrick’s (1982) revision of the genus Carcharhinus, he noted that Western Pacific and Western Indian Ocean specimens of C. sealei differed in a number of characters and stated that they could be treated as separate species or subspecies. His reluctance to consider the Western Indian Ocean population as a distinct species was due to the lack of specimens between these locations and he concluded that these differences could just represent the end segments of a continuous distribution; a justifiable position to take with the data available. However, as discussed by White (2012), there are no validated records of C. sealei from west of the Indo–Malay Archipelago. The characters which Garrick (1982) reported to differ between the Western Indian and Western Pacific populations are: higher second dorsal fin, longer prenarial and preoral lengths, typically smooth-backed (vs. low interdorsal ridge present), and anterior margin of eye located slightly anterior to front of mouth (vs. slightly posterior). In this study, the new Western Indian Ocean species was found to usually possess a weak interdorsal ridge, while most C. sealei examined lacked an interdorsal ridge. The longer prenarial and preoral lengths and higher second dorsal fin appear to be the best morphological characters to separate C. humani from C. sealei: horizontal prenarial length 4.1–4.7 vs. 3.4–4.2% TL, snout tip to inner nostril 4.8–5.4 vs. 3.9–4.7% TL, preoral length 6.8–7.6 vs. 5.7–6.5% TL, second dorsal-fin height 4.0–4.5 vs. 2.8–3.8% TL, 39.3–47.6 vs. 30.9–37.3% of first dorsal-fin height.
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A number of other characters were found to be useful in separating C. humani and C. sealei, in particular the coloration of the second dorsal fin. In C. sealei, the black apical marking on the second dorsal fin covers the majority of the fin, usually extends slightly onto the dorsal surface of the body and its lower edge is diffuse. In contrast, in the new species, the black marking is restricted to the upper one or two thirds of the fin, does not extend onto body surface, and is sharply demarcated from paler fin colour. This character is considered to be particularly useful in separating these two species if based on fresh or recently preserved material. Other morphological characters which were found to differ between C. humani and C. sealei are: longer pre-first dorsal length (28.2–30.6 vs. 26.3–27.6% TL); shorter first dorsal fin (its length 13.4–14.6 vs. 14.7–16.0% TL, 2.0–2.3 vs. 1.7–1.9 in pre-first dorsal length); pelvic-fin anterior margin/pectoral-fin anterior margin ratio (0.45–0.49 vs. 0.38–0.44); and a slightly more slender tail (its height 7.4–8.3 vs. 8.8–9.9% TL). The new species is also similar morphologically to C. coatesi from northern Australia and New Guinea. The black apical markings in both of these species are similar in being strongly demarcated from the paler region of the fin and not extending onto the dorsal surface of the body. Carcharhinus humani is most readily distinguished from C. coatesi in having more vertebrae (total centra 152–167 vs. 134–147; precaudal centra 74–85 vs. 67–76) and in structure of the CO1 gene (~7% divergent). The new species can also be distinguished from C. coatesi in having a taller second dorsal fin (its height 4.0–4.5 vs. 2.9–3.6% TL) and shorter first dorsal fin (its length 13.4–14.6 vs. 14.8–17.3% TL, 3.2–3.3 vs. 4.1–5.6 times second dorsal-fin height).
Key to species of the dussumieri-sealei group 1. 2. 3. 4. -
First dorsal fin moderately to slightly falcate at all sizes; snout not flattened, rounded in dorsoventral view, narrowly rounded in lateral view; total vertebrae >134 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 First dorsal fin not falcate (except in some small juveniles); snout slightly flattened, slightly pointed in dorsoventral view, narrowly pointed in lateral view; total vertebrae
