Smithophis, Giri & Gower & Das & Lalremsanga & Lalronunga & Captain & Deepak, 2019

Giri, Varad B., Gower, David J., Das, Abhijit, Lalremsanga, H. T., Lalronunga, Samuel, Captain, Ashok & Deepak, V., 2019, A new genus and species of natricine snake from northeast India, Zootaxa 4603 (2), pp. 241-264 : 245

Smithophis gen. nov.

urn:lsid:zoobank.org:act:444965CF-9756-4EF1-83B5-41051AE0F256

Type species. Smithophis atemporalis gen. et. sp. nov., by original designation.

Diagnosis. Natricine snakes with the following combination of characters: (1) a single (‘fused’ or unpaired) internasal shield and a single prefrontal shield, (2) internasal very broad and not or only slightly tapered anteriorly, (3) smooth, unkeeled dorsal scales, (4) fewer than six pairs of supralabial shields, (5) 17 rows of dorsal scales at midbody, (6) C-shaped, valvular external nares, (7) eyes with rounded or elliptical pupils, and (8) eye diameter substantially smaller than distance between eye and naris.

Remarks. The new genus is clearly monophyletic and most closely related to a monophyletic Opisthotropis in our molecular phylogenetic trees, and the two genera are similar phenotypically in having a single prefrontal shield (paired in a few species of Opisthotropis ). Molecular phylogenetic support for Opisthotropis monophyly is not yet compelling though clearly stronger than for its non-monophyly, but we have elected to erect a new genus given also that (1) Smithophis gen. nov. is distinct from Opisthotropis in also having a single internasal shield (which, in concert with the single prefrontal, is a unique condition among natricines), in having fewer than 6 supralabial shields on each side, and in having internasal(s) that are not or only slightly anteriorly tapered, and (2) because the phylogenetic relationships of several key taxa remain unclear given incomplete taxon sampling thus far in phylogenetic analyses—in this context we are thinking particularly of the type species of Opisthotropis ( O. ater Günther, 1872 ), and any representatives of any of the at least superficially similar (David et al. 2015) monotypic Isanophis David et al. 2015 , and Paratapinophis Angel, 1929 (though it might be noted that the latter three taxa also differ from Smithophis gen. nov. in having paired internasals that are not notably broad and which taper anteriorly, and in having more than 6 supralabials).

All specimens of Smithophis we have observed have a single internasal shield and, to the best of our knowledge, all specimens of Opisthotropis have paired internasals. Species of all synonyms of Opisthotropis have paired rather than single internasals. Single internasals are derived, providing additional evidence to support the monophyly of the new genus. Wall (1908: 322–323) considered the unusual head shields of Rhabdops bicolor distinctive enough that it was “extremely probable that it will have to be separated and relegated to a genus by itself”.

Content. Two nominal species; the type species (described below) and S. bicolor (Blyth, 1854) .

Etymology. Named in honour of Malcolm A. Smith (1875–1958) in recognition of his many contributions to herpetology and especially to the knowledge of Asian snakes.

Distribution. Northeast India, from Meghalaya state, northeast India east to Myanmar and possibly western Yunnan, China ( Anderson 1879; Pope 1935; Smith 1943; Dowling & Jenner 1988; Wallach et al. 2014).