DASYATIDAE (WHIPTAIL STINGRAYS)

Henderson, Aaron C., Reeve, Alan J., Jabado, Rima W. & Naylor, Gavin J. P., 2016, Taxonomic assessment of sharks, rays and guitarfishes (Chondrichthyes: Elasmobranchii) from south-eastern Arabia, using the NADH dehydrogenase subunit 2 (NADH 2) gene, Zoological Journal of the Linnean Society 176 (2), pp. 399-442 : 423-428

DASYATIDAE (WHIPTAIL STINGRAYS)

Eight putative species were assessed. They exhibited a between-group mean distance of 14.93 ± 0.87%. Specimens originally identified as Himantura gerrardi during the present study formed two geographically distinct clusters with strong branch support, one containing ten specimens from Oman, and the other containing four specimens from the UAE. The latter was further divided into two groups, also with strong branch support, with three specimens on one branch and one specimen on the other ( Fig. 2 ). When assessed alongside related taxa from Naylor et al. (2012), the Oman and UAE clusters were separated further ( Fig. 4 ). The group containing the ten specimens from Oman clustered with a single specimen from Iran, which Naylor et al. (2012) designated H. cf. gerrardi 3, remaining distinct from four other H. cf. gerrardi clusters ( Naylor et al., 2012). Furthermore, the single specimen from the UAE clustered with Himantura randalli , while the other three UAE specimens formed a distinct cluster. The current specimens have therefore been labelled H. cf. gerrardi 3, Himantura randalli and Himantura sp. ( Fig. 5 ). Mean distance was high between H. cf. gerrardi 3 and each of the other two taxa, while the latter were more modestly separated ( Table 2).

A similarly complex situation was observed within specimens that were originally identified as H. uarnak during the present study. These seven specimens formed two distinct clusters, one consisting of two specimens and the other containing the remaining five specimens, and they exhibited a between-group mean distance of 9.97 ± 1.09%. Naylor et al. (2012) reported six distinct clusters within this species complex: four H. cf. uarnak clusters, H. undulata and H. leoparda . The first cluster from the present study grouped with H. cf. uarnak 3 (a cluster consisting of specimens from Singapore, Malaysia and Indonesia), while the second cluster grouped with, but beside, H. leoparda ( Fig. 4 ).

Four Pastinachus specimens that were tentatively identified as P. sephen during the present study clustered with 14 specimens of P. atrus from Naylor et al. (2012). Unfortunately, no confirmed specimens of P. sephen were available to Naylor et al. (2012), although three assumed specimens from Iran (designat- ed P. cf. sephen ) clustered away from the P. atrus specimens. The current specimens are therefore assumed to be P. atrus , and they formed two sub-clusters with strong branch support. However, their betweengroup mean distance was only 1.03 ± 0.35%.

Naylor et al. (2012) reported four Neotrygon kuhlii clusters, which they designated N. cf. kuhlii 1–4. Specimens from the present study clustered with N. cf. kuhlii 3, which had been represented by a single specimen from Madagascar. With the exception of one specimen, which was identified as Dasyatis sp. in the field and which clustered with a Dasyatis ushiei specimen from Malaysia, the remaining dasyatid species clustered with the relevant taxa from Naylor et al. (2012).

Figures

Figure 2. Neighbour-joining tree for an 829-bp fragment of the NADH2 gene from 1487 elasmobranch specimens from south-eastern Arabia. Values in parentheses indicate sample size (n) and within-group mean genetic distance (D). Bootstrap values are based on 1000 replications and only values ≥ 95% are shown.

Figure 4. Neighbour-joining tree for an 829-bp fragment of the NADH2 gene for dasyatid rays from southeastern Arabia together with related taxa from Naylor et al. (2012). Bootstrap values are based on 1000 replications and only values ≥ 95 % are shown.

Figure 5. Himantura sp. from Fujairah in the United Arab Emirates. This species clusters separately from all other ray species from the region.