A. Homalopsis buccata, B. H. mereljcoxi,
C. H. nigroventralis, D. H. semizonata.
Photo credits: R. Steubing, J. C. Murphy,
and J. Vidum
Masked water snakes of the genus Homalopsis are the largest members of the family Homalopsidae, exceeding 1.3 m, and are abundant in the low elevation wetlands of Southeast Asia. They have robust bodies, wide heads, distinctive pattern of alternating brown and cream bands outlined in black, and often a pale colored venter with paired dark spots on the lateral edge of the ventrals and first dorsal rows of scales. Masked water snakes are nocturnal ambush predators preying on small fish, and their large size and interesting dorsal pattern makes them a target for the novelty leather industry. Homalopsis is harvested in large numbers at Tonle Sap, Cambodia for its skin and protein. Only one species of Homalopsis was recognized for the majority of the last 250 years until H. nigroventralis was resurrected in 2006. Despite its distribution, abundance, and excessive exploitation, the systematics of Homalopsis and Linnaeus’ original description of Coluber buccatus in 1758 the genus and species has remained poorly studied. Murphy and colleagues analyzed 163 specimens of Homalopsis and found three cryptic species within the genus, bring the total known species to five. These species are based upon relatively subtle morphological characters that follow geographical patterns, and in part explain why these cryptic species have been long confused. Two of the five now known species were previously described; the third had no available name. With the exception of H. nigroventralis, there is no way to identify these species at a glance; scale characteristics and counts need to be examined in detail. The authors recognize Homalopsis hardwickii Gray a species known only from the type specimen and from an unknown location, but presumably somewhere in “India;” and H. semizonata Blyth a species from Myanmar with three prefrontal scales; H. buccata is the type species of the genus and found throughout the Indonesian archipelago, and H. nigroventralis a melanistic species of the Mekong drainage system originally described as a subspecies of H. buccata, and know known from Cambodia and Thailand as well. The new species H. mereljcoxi is, ironically, the most exploited species and is found in Thailand and the Indochinese Peninsula.
Murphy, J. C., Voris, HK, MurthyBHCK, Traub, J, and Cumberbatch, C. 2012. The maskedwater snakes of the genus Homalopsis Kuhl & van Hasselt, 1822 (Squamata,Serpentes, Homalopsidae), with the description of a new species. Zootaxa