Carcharhinus dussumieri

White, William T., 2012, A redescription of Carcharhinus dussumieri and C. sealei, with resurrection of C. coatesi and C. tjutjot as valid species (Chondrichthyes: Carcharhinidae), Zootaxa 3241, pp. 1-34 : 30-31

Carcharhinus dussumieri subgroup

Carcharhinus dussumieri and C. tjutjot differ in shape of the pectoral fin, with the latter species having broader and less falcate pectoral fins with a more broadly rounded apex vs. a narrowly rounded to somewhat angular apex. The former species also possesses a more broadly triangular first dorsal fin than the latter species. Carcharhinus dussumieri usually lacks an interdorsal ridge whereas C. tjutjot has a moderate to strong ridge in the majority of specimens.

Carcharhinus dussumieri and C. tjutjot are morphologically very similar to each other. Comparisons of the morphological data taken in this study needs to take into account that a relatively small sample size of a wide size range were measured for these two species. As a result, it is important to make comparisons between similar-sized individuals. When comparing specimens of C. dussumieri and C. tjutjot of less than 500 mm TL (n = 3 for both species), they differed in the following morphological characters: shorter first dorsal fin (length 14.3–14.5 vs.

15.5–15.6% TL), gills larger (height of third gill slit 3.3–3.6 vs. 2.7–3.3% TL, height of fifth gill slit 2.6–2.8 vs. 1.8–2.4% TL), a slightly shallower body (abdomen height 9.9–11.6 vs. 11.6–13.1% TL), tail width 5.1–6.4 vs. 6.5– 6.8% TL, a longer pectoral-fin inner margin (6.1–6.4 vs. 5.3–5.9% TL), DPI/DPO ratio 1.29–1.53 vs. 1.50–1.95, and anal-fin height / second dorsal-fin height ratio 1.01–1.22 vs. 1.23–1.35.

While the total tooth counts overlap, Carcharhinus dussumieri often has more teeth than specimens of C. tjutjot (52–59 vs. 51–54), reflected best in the upper lateral tooth counts, i.e. 13 or 14 vs. 12 or 13 ( Table 4 ). Similarly, the vertebrae counts overlapped but Carcharhinus dussumieri often has more, e.g. monospondylous centra 42–48 vs. 37–44, precaudal centra 62–68 vs. 55–63, total centra 123–138 vs. 113–129 (Table 3). Although the vertebral counts do overlap, this will likely be a useful character to separate at least a large proportion of individuals of this species. The wide range in vertebral counts reported for C. dussumieri in Garrick (1982) can be explained in part by the fact that two species, C. dussumieri and C. tjutjot are involved.