Eusphyra laticeps (Cantor)

Fernando, Daniel, Bown, Rosalind M. K., Tanna, Akshay, Gobiraj, Ramajeyam, Ralicki, Hannah, Jockusch, Elizabeth L., Ebert, David A., Jensen, Kirsten & Caira, Janine N., 2019, New insights into the identities of the elasmobranch fauna of Sri Lanka, Zootaxa 4585 (2), pp. 201-238 : 226

Eusphyra laticeps (Cantor)

( Figs. 4F , 16 A–C)

One of the most intriguing specimens (SL-3) examined in Sri Lanka was caught in the Gulf of Mannar and landed at Palkanththura in the North Western Province. The distinctive narrow blades of its wing-shaped head seemed to unambiguously confirm its identity as Eusphyra blochii (Cuvier) . However, it was found to differ from our reference specimen of E. blochii (AU-83; JQ519152 ) from Australia by 46 bp. This substantial difference in NADH2 sequence suggests that the form from Sri Lanka may represent a second species of winghead shark. Although generally considered a synonym of E. blochii , Eusphyra laticeps is a candidate name for the Sri Lankan form. This species was described by Cantor (1837), as Zygaena laticeps Cantor , from the Bay of Bengal and, based on Cantor’s description, clearly exhibits the extremely expanded head that is diagnostic of E. blochii— a feature also seen in the specimen from Sri Lanka. The potential existence of two species with this characteristic head raises an interesting question regarding the identity of E. blochii for which the type locality is unknown ( Gilbert, 1967), but which is currently considered to be distributed throughout the Indo-West Pacific ( Compagno, 1984). Clearly examination of additional specimens and comparison with specimens from other localities in the Indo-West Pacific is in order.

It seems likely that this is the taxon in Sri Lanka referred to as Sphyrna blochii Cuvier by Goonewardene (1971) and De Silva (1977) and as E. blochii by De Silva (1984 –1985, 2006, 2015), De Bruin et al. (1995), Morón et al. (1998), and Joseph 1999.

Figures

FIGURE 4. Neighbor-Joining trees of p-distances based on 1,044 bp of aligned NADH2 sequence data for individual selachian genera or groups of genera. Taxon names are followed by country, host specimen number (in parentheses), and GenBank number. Outgroup taxa used in each analysis were omitted from the individual trees. Scale bar values indicate substitutions per site. Specimens deposited in the Blue Resources Trust Ichthyology Collection are indicted by stars (see text for details). A. Carcharhinus and close relatives (Carcharhinidae). B. Rhizoprionodon (Carcharhinidae). C. Galeocerdidae. D. Hemigaleidae. E. Pseudotriakidae. F. Sphyrnidae. G. Iago (Triakidae).

FIGURE 16. Eusphyra laticeps (Sphyrnidae) (A–C) and Iago cf. omanensis 1 (Triakidae) (D–G). A. Lateral view of mature male (SL-3). B. Dorsal view of head of mature male (SL-3). C. Ventral view of head of mature male (SL-3). D. Lateral view of female (SL-79; BRT-I 0019). E. Ventral view of head of female (SL-79; BRT-I 0019). F. Lateral view of mature male (SL-80; BRT-I 0020). G. Ventral view of head of mature male (SL-80; BRT-I 0020).