Brevitrygon, Last, Naylor & Manjaji-Matsumoto, 2016

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 : 207-208

Brevitrygon sp. 1

( Figs. 2B , 6C, D )

Specimens of a species of Brevitrygon Last, Naylor & Manjaji-Matsumoto were examined from the Palkanththura market (SL-5) in the North Western Province, from the Munai (SL-30, SL-35, SL-36, SL-37) and Erinchamman Kovilady (SL-48, SL-49) markets in Point Pedro in the Northern Province, and from Mutur (SL-73, SL-74) in the Eastern Province. In the tree resulting from the Neighbor-Joining analysis, these nine specimens clustered together away from our reference specimens of Brevitrygon heterura (Bleeker) (BO-239; JQ518798 ) from Malaysian Borneo, of B. imbricata (IN-15; MK335257 ) from India, and of Brevitrygon walga (Müller & Henle) (MM-12; JQ518825 ) from the Gulf of Oman. The specimens from Sri Lanka differed from one another by 0–8 bp. They were highly divergent from the three reference species, differing from the B. heterura specimen by 62–67 bp, from the B. imbricata specimen by 62–67 bp, and from the B. walga specimen by 97–102 bp. Morphologically, the specimens from Sri Lanka differ from all of their congeners except Brevitrygon javaensis (Last & White) , which unfortunately was not included in our molecular analysis, in bearing few to no enlarged thorns on the base of the tail. However, the Sri Lankan specimens differ conspicuously from B. javaensis in their possession of a narrow, rather than broad, denticle band (see Last & White 2013). As a consequence, it seems likely that the form from Sri Lanka represents a new species and has been referred to here with the provisional name Brevitrygon sp. 1.

This may be the species from Sri Lanka referred to as Himantura imbricata (Bloch & Schneider) by previous authors (e.g., De Bruin et al. 1995; Morn et al. 1998; De Silva 2006).

Figures

FIGURE 2. Neighbor-Joining trees of p-distances based on 1,044 bp of aligned NADH2 sequence data for individual batoid 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. Aetobatus (Aetobatidae). B. Brevitrygon (Dasyatidae). C. Himantura (Dasyatidae). D. Maculabatis (Dasyatidae). E. Neotrygon (Dasyatidae). F. Pastinachus (Dasyatidae). G. Pateobatis (Dasyatidae). H. Urogymnus (Dasyatidae).

FIGURE 6. Aetobatus ocellatus (Aetobatidae) (A–B) and Brevitrygon sp. 1 (Dasyatidae) (C–D). A. Dorsal surface of immature male (SL-26). B. Dorsal surface of mature female (SL-41). C. Dorsal surface of maturing male. D. Thorns and denticles on base of tail of mature male (dorsal surface; SL-36).