Sunday, January 27, 2019

[Herpetology • 2019] Xylophiinae subfam. nov. • A New Subfamily of Fossorial Colubroid Snakes from the Western Ghats of Peninsular India

Geographic distribution of Xylophiinae subfam. nov. (green) 
and approximate distribution of subfamily Pareinae (blue).

Deepak, Ruane & Gower, 2019. 

We report molecular phylogenetic and dating analyses of snakes that include new mitochondrial and nuclear DNA sequence data for three species of the peninsular Indian endemic Xylophis. The results provide the first molecular genetic test of and support for the monophyly of Xylophis. Our phylogenetic results support the findings of a previous, taxonomically restricted phylogenomic analysis of ultraconserved nuclear sequences in recovering the fossorial Xylophis as the sister taxon of a clade comprising all three recognised extant genera of the molluscivoran and typically arboreal pareids. The split between Xylophis and ‘pareids’ is estimated to have occurred on a similar timescale to that between most (sub)families of extant snakes. Based on phylogenetic relationships, depth of molecular genetic and estimated temporal divergence, and on the external morphological and ecological distinctiveness of the two lineages, we classify Xylophis in a newly erected subfamily (Xylophiinae subfam. nov.) within Pareidae.

KEYWORDSAsia, classification, Pareidae, Pareinae, phylogenetics, Xylophis, taxonomy

Figure 4. (a) Geographic distribution of Xylophiinae subfam. nov. (green) and approximate distribution of subfamily Pareinae (blue).
 Photographs show representative taxa of the two subfamilies within Pareidae: (b) Xylophis perroteti from Nilgiris, Tamil Nadu, India (Photo: Achyuthan N. Srikanthan); (c) Pareas monticola from Barail, Assam, India (Photo: V. Deepak).
Approximate distribution drawn based on locations provided in Srinivasulu et al. (2014) and Wallach et al. (2014).

DIAPSIDA Osborn, 1903
Superorder LEPIDOSAURIA Haeckel, 1866

Order SQUAMATA Oppel, 1811
Suborder SERPENTES Linnaeus, 1758
Infraorder CAENOPHIDIA Hoffstetter, 1939
Superfamily COLUBROIDEA Oppel, 1811

Family PAREIDAE Romer, 1956

Subfamily Xylophiinae subfam. nov.

Type genus: Xylophis Beddome, 1878

Content A single genus with three currently recognised species: X. stenorhynchus (Günther, 1875); X. perroteti Duméril, Bibron and Duméril, 1854; X. captaini Gower and Winkler, 2007. 
Xylophis indicus Beddome, 1878 has been considered a synonym of X. stenorhynchus (e.g. Smith 1943; Wallach et al. 2014) but might also be valid (Gower and Winkler 2007). Xylophis perroteti includes the synonyms Rhabdosoma microcephalum Günther, 1858 (e.g. Smith 1943; Wallach et al. 2014).

Diagnosis Colubroid snakes with first (anteriormost) three pairs of infralabial shields reduced to narrow strips, together much smaller than large pair of anterior chin (genial) shields.

 Distribution The Western Ghats region of peninsular India. ...

V. Deepak, Sara Ruane and David J. Gower. 2019. A New Subfamily of Fossorial Colubroid Snakes from the Western Ghats of Peninsular India. Journal of Natural History.   52(45-46)  DOI: 10.1080/00222933.2018.1557756