Sunday, September 28, 2014

[Herpetology • 2014] A Checklist and Key to the Homalopsid Snakes (Reptilia, Squamata, Serpentes), with the Description of New Genera

TABLE 2. Homalopsid species are grouped based on morphological and molecular work.
 The Fangless Indonesian Group was recently recognized and placed within the Homalopsidae by Murphy et al. (2011). (Photo A Brachyorrhos raffrayi by J.C.M.) Alfaro et al. (2008) recognized four clades. Their clade A corresponds with our Plumbea Group, containing a highly aquatic undescribed species from Lake Towuti, Sulawesi. (Photo B Hypsiscopus plumbea by Daryl R. Karns.) The South China Group is linked by similar morphology, and was long considered to be part of Enhydris. Kumar et al. (2012) found Myrrophis chinensis to be the sister to the southwest Indian Dieurostus dussumierii (also previously considered part of Enhydris). (Photo C Myrrophis chinensis by Steve Mackessy.) The two species in the Fossorial-Aquatic Group share similar morphology and geography but remain unconfirmed by molecular studies. (Image D Miralia alternans from Jan & Sordelli, 1860–1881.) Similarly, most members of the South Asian Group have not been included in molecular studies. The group shares some morphology and geography. (Photo E Dieurostus dussumierii by Biju Kumar.) The Pahang Mud Snake, Kualatahan pahangensis, is of uncertain relationship. It may be allied with the South Asian Group or the Enhydris Group. The Enhydris Group is centered in Indochina, they use freshwater habitats, and group membership of all but Enhydris chanardi has been supported with molecular and morphological data (Alfaro et al., 2008; Karns et al., 2010a). (Photo F Enhydris enhydris by J.C.M.) The Punctata Group is centered on the Sunda Shelf and shares similar morphology. Only Phytolopsis punctata has been included in molecular studies. (Photo G Homalophis doriae by Daryl R. Karns.) The Saltwater Group has been well documented with molecular data (Alfaro et al., 2008). (Photo H Cantoria violacea by J.C.M.) The Australasian Group is well supported by a close genetic relationship between Pseudoferania and Myron (Alfaro et al., 2008; Kumar et al., 2012; Pyron et al., 2013) and shared morphology and geography with the other members of the group. (Photo I Pseudoferania polylepis by J.C.M.) The Sunda Group is at best tentative, Alfaro et al. (2008) found a sister relationship between Erpeton and Subsessor bocourti, while Murphy et al. (2011) found Erpeton to be the sister to Bitia, and Subsessor to be the sister to the Homalopsis and Cerberus groups; and Kumar et al. recovered Subsessor as the sister to Homalopsis. (Photo J Subsessor bocourti by J.C.M.) The Homalopsis Group is linked by similar morphology. (Photo K Homalopsis mereljcoxi by J.C.M.) The Cerberus Group has three of the five species linked with molecular data (Alfaro et al., 2004) and is strongly supported by Alfaro et al. (2008). (Photo L Cerberus dunsoni by J.C.M.)

The colubroid snake family Homalopsidae contained 10 genera and 34 species of rear-fanged semi-aquatic and aquatic snakes in 1970 with the publication of Gyi's monograph. In 2007 Murphy had updated Gyi's work and the family held the same 10 genera with 37 species plus two genera with uncertain status (Anoplohydrus, Brachyorrhos). Molecular studies published in the first decade of the 21st century demonstrated that while the Homalopsidae is monophyletic, the species-rich genus Enhydris is polyphyletic. Molecular analysis also found Brachyorrhos to be the most basal member of the clade, confirming an earlier hypothesis that it was a fangless homalopsid. Subsequently, two other fangless genera of homalopsids were discovered. We revalidate the genera: Homalophis Peters, Hypsiscopus Fitzinger, Miralia Reuss, Phytolopsis Gray, and Raclitia Gray. Also, we describe five new genera for species lacking available names: Gyiophis, Kualatahan, Mintonophis, Sumatranus, and Subsessor. The new arrangement for homalopsid names resolves the problem of the formerly polyphyletic genus Enhydris. For all species, we provide a synonymy, information on types and type localities, a diagnosis, as well as remarks on taxonomic and nomenclatural problems and a dichotomous key. Recent evidence suggests homalopsids show high levels of endemism and cryptic speciation.

Keywords: aquatic snakes, mud snakes, Homalopsidae, terrestrial–aquatic transition, geographic distribution, taxonomy

CoverEnhydris jagorii Peters from the Bung Ka Lo wetland in Thailand’s Central Plain. This is the only confirmed extant population of this snake. Enhydris jagorii inhabits a marshy wetland with a shallow central lake bordered by rice paddy.
Photo by J.C.M.

John C. Murphy and Harold K. Voris. 2014. A Checklist and Key to the Homalopsid Snakes (Reptilia, Squamata, Serpentes), with the Description of New Genera. Fieldiana Life and Earth Sciences. 8 :1-43. doi: