Chiloscyllium, Muller & Henle, 1837

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 : 229-231

Chiloscyllium sp. 1

( Figs. 5D , 17 I–K)

Six specimens of an interesting species of Chiloscyllium Müller & Henle were examined from the Munai (SL-31) and Kottadi (SL-32, SL-59, SL-60) markets at Point Pedro, and Vankalai (SL-65, SL-70) in the Northern Province. Immature specimens of this species exhibited brown bands and saddles that persisted, but were less conspicuous, in adults. Morphologically, among its congeners, these specimens most closely resemble Chiloscyllium arabicum , particularly in fin shape and position. Our molecular analysis included six of the eight described and both undescribed members of the genus (i.e., Chiloscyllium cf. punctatum 1 of Naylor et al. [2012a] from Australia and Chiloscyllium cf. punctatum 2 from Taiwan of Straub et al. [2013]). Because of the resemblance to C. arabicum , we included newly generated NADH2 data for a reference specimen (MM-903; MK335259 ) of the latter species from the Gulf of Oman. In the tree resulting from the Neighbor-Joining analysis, the specimens from Sri Lanka formed a distinct cluster, differing from one another by 1–4 bp. They grouped most closely with our reference specimen of Chiloscyllium hasselti Bleeker (KA-164; JQ519066 ) from Indonesian Borneo. However, they differed from this specimen by 37–43 bp. They were even more divergent from C. arabicum and Chiloscyllium griseum Müller & Henle , differing from the reference specimen of the former species by 109–124 bp and from that of the latter species by 100–115 bp. With respect to the two known species not included in our molecular analysis, the specimens from Sri Lanka conspicuously differ from both. They lack the blue-white spots characteristic of Chiloscyllium caeruleopunctatum Pellegrin (see Compagno 1984) and the diagnostic dark fin webs of Chiloscyllium burmensis (see Dinkerkus & DeFino 1983). It could be argued that these specimens raise a question regarding the validity of Chiloscyllium confusum Dingerkus & DeFino—a species originally described from India by Dingerkus & DeFino (1983), but synonymized with C. arabicum (see Randall 1995). However, Dingerkus & DeFino (1983; pg. 11) differentiated C. confusum from all of its congeners, including C. arabicum , on the basis of the fact that "This is the only species of Chiloscyllium in which the immature body color is uniform, and identical with that of the adult", yet all of our specimens (immatures and adults) exhibit a clear pattern of brown bands and saddles. Furthermore, unlike C. confusum our Sri Lankan specimens exhibit a first dorsal fin base that is longer, rather than shorter, than the second dorsal fin base. It thus seems apparent that our specimens represent an undescribed species. We have provisionally referred to them here as Chiloscyllium sp. 1. An immature male of this species was deposited in the BRT Ichthyology Collection (SL-32; BRT-I 0011).

It seems likely that this is the species that has been previously reported as C. griseum from Sri Lanka (e.g., De Silva 1984 –1985, 2006, 2015; De Bruin et al. 1995; Morón et al. 1998; Joseph 1999). If so, the presence of C. griseum in Sri Lanka remains to be confirmed.

Figures

FIGURE 5. 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. Echinorhinidae. B. Hexanchidae. C. Lamniformes. D. Chiloscyllium (Hemiscylliidae). E. Centrophorus (Centrophoridae). F. Somniosidae/Oxynotidae (Somniosus omitted).

FIGURE 17. Echinorhinus sp. 1 (Echinorhinidae) (A–D), Hexanchus griseus (Hexanchidae) (E–H), and Chiloscyllium sp. 1 (Hemiscylliidae) (I–K). A. Lateral view of female (SL-108). B. Ventral view of head of female (SL-108). C. Teeth of upper jaw of female (SL-108). D. Teeth of lower jaw of female (SL-108). E. Lateral view of immature male (SL-106). F. Ventral view of head of female (SL-91). G. Teeth of upper jaw of female (SL-91). H. Teeth of lower jaw of female (SL-91). I. Lateral view of mature male. J. Ventral view of head of mature male (SL-59). K. Dorsal view of head and trunk of mature male (SL-59).