Iago cf. omanensis (Norman, 1939)

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 : 226-227

Iago cf. omanensis 1

( Figs. 4G , 16 D–G)

The existence of undescribed diversity in the Iago omanensis (Norman) species complex from elsewhere across the globe (see Naylor et al. 2012a) complicates identification of the specimens of this genus examined in Sri Lanka, six of which (SL-79, SL-80, SL-81, SL-82, SL-83, and SL-84) were collected at the Mutur landing site in the Eastern Province in 2018, and one of which (SL-114) was collected at the Peliyagoda Fish Market in Colombo, in the Western Province. Based on morphology, we initially thought we had encountered two different species of Iago . In one case (i.e., SL-80; Fig. 16F ), the second dorsal fin was only slightly larger than the anal fin, and the anal fin origin was located slightly anterior to the middle of the second dorsal fin with the anal fin posterior rear tip extending posterior to that of the second dorsal fin; this specimen has been deposited in the BRT Ichthyology Collection (BRT-I 0020). In contrast, in the other six specimens (SL-79 [ Fig. 16D ], SL-81, SL-82, SL-83, SL-84, and SL-114), the second dorsal fin was conspicuously larger than the anal fin and the anal fin origin was only slightly posterior to the origin of the second dorsal fin with the posterior rear tip of the second dorsal fin extending to approximately the same level as that of the anal fin; a female specimen of this form was deposited in the BRT Ichthyology Collection (SL-79; BRT-I 0019). However, this distinction was not supported by our molecular data. In the tree resulting from the Neighbor-Joining analysis of NADH2 data, all seven specimens from Sri Lanka formed a tight cluster with the reference specimen of the undescribed species from India given the designation Iago cf. omanensis 1 ( JQ518697 ) by Naylor et al. (2012a). Two subclusters were evident within this cluster. The three specimens in the first subcluster, which included the reference specimen from India, were identical in sequence; the five specimens in the second subcluster differed from one another by 0–2 bp. Although the subclusters differed from one another by 6–7 bp, the first subcluster included specimens of both morphological forms.

In terms of existing names for I. cf. omanensis 1, we gave some consideration to whether Iago mangalorensis (Cubelio, Remya & Kurup) , originally described as Mustelus mangalorensis Cubelio, Remya & Kurup from a specimen in a fish collection in India, collected from Mangalore on the west coast of India, was appropriate. However, based on Cubelio et al. 's (2011) original description, the extremely pointed snout, among other features, is inconsistent with the specimens from Sri Lanka. The other potential candidate is the taxon referred to by Compagno et al. (2005) as Iago sp. A occurring off the northwestern coast of Sri Lanka. However, the low dorsal fins and small pectoral fins of this taxon are inconsistent with those of our specimens from Sri Lanka. We would note that there appears to be some confusion in the literature regarding the identities of I. mangalorensis and I. sp. A, given that the illustrations and description of the former species in Ebert et al. (2013) is actually of the latter taxon as defined by Compagno et al. (2005).

This may be the species reported previously from Sri Lanka by Morón et al. (1998) as Iago omanensis . However, species of Mustelus Linck have commonly also been reported (e.g., De Silva 1984 –1985, 2006, 2015; De Bruin et al. 1995; Joseph 1999) and thus generic verification of reports of triakid sharks more broadly from the region should be a future priority.

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).