Sea snakes (Serpentes: subfamilies Hydrophiinae and Laticaudinae) in Vietnam: a comprehensive checklist and an updated identification key

Abstract

Sea snakes (Elapidae, subfamilies Hydrophiinae and Laticaudinae) reach a very high species richness in Southeast Asia, but most countries in the region still lack comprehensive and up-to-date identification tools for these snakes. We present an updated checklist of sea snakes in Vietnam. We also provide diagnostic characters for all species and a new complete identification key, chiefly based on easy-to-use external characters. The checklist and key cover the 25 species documented from Vietnam, as well as three likely future additions to its sea snake fauna. By surveying incoming fishing vessels between Nha Trang and the mouth of Mekong River in 2000–2001, we were able to document two species new for Vietnamese waters: Hydrophis belcheri and H. pachycercos. Through these surveys we also secured four specimens of the rare endemic species H. parviceps, formerly known only from two specimens. A comprehensive bibliography of the literature treating sea snakes in Vietnamese waters is provided.Identification key: bibliography, biodiversity, diagnostic characters, Vietnamese waters

Trophic specialization drives morphological evolution in sea snakes

“…Total length was recorded for adults of both sexes, which were identified by large, non-flaccid testes in males and thickened oviducts and/or visible vitellogenic follicles in females. Additional body length data were collated from the literature [ 23 – 25 ] to estimate the maximum total length for each species. For body length data, most species were represented by very large numbers of specimens, with the exception of a few poorly known taxa.…”

Recent rapid speciation and ecomorph divergence inIndo‐Australian sea snakes

“…Morphological data were collected for 122 museum and field-collected specimens representing the four species (42 Hydrophis melanocephalus, 45 H. coggeri, 30 H. cyanocinctus and five H. parviceps). We examined four ecologically significant traits involving body size and proportions, in addition to nine taxonomically important scalation and colour pattern characters previously used to delimit the four species (Smith 1926;Rasmussen et al 2011b). Morphometric characters (recorded to the nearest 1.0 mm using string and a ruler) were: body length measured from snout to vent (SVL), tail length from vent to tip of the tail, girth at the neck and girth at 0.75 SVL.…”

“…These results appear most consistent with separate origins of microcephaly (from an ancestral H. cyanocinctus morphotype) in at least H. coggeri and H. melanocephalus. The alternative scenario of microcephaly evolving only once (in the ancestor of the H. coggeri, H. melanocephalus, H. parviceps and eastern H. cyanocinctus clade), with secondary increase in head and fore-body size and body length occurring in eastern H. cyanocinctus, is also plausible but requires re-evolution of several other morphological traits not obviously correlated with macrocephaly in eastern H. cyanocinctus (Smith 1926;Rasmussen et al 2011b;Rasmussen and Sanders unpublished data).…”

Sea snakes (Elapidae, Hydrophiinae) in their westernmost extent: an updated and illustrated checklist and key to the species in the Persian Gulf and Gulf of Oman

“…Data of all measurements are in mm. Due to great interspecific and intraspecific variations in external characters of sea snakes (Rasmussen et al 2011), diagnostic characters provided here are mostly applicable to the specimens from this area. Morphological data derived from previous literature dealing with sea snakes in the area are mentioned in brackets.…”

“…Now, more than 60 morphologically and ecologically diverse species of highly venomous marine hydrophiines live throughout tropical and subtropical coastal waters of the Indo-West Pacific region (Rasmussen et al 2011b), with an exception, the Yellow-bellied Sea Snake, Hydrophis platurus (Linnaeus, 1766), that lives in both Indian and Pacific Oceans (Heatwole 1999). These sea snakes colonize various coastal habitats throughout their geographic range and play an important role in the food web of these coastal biomes by consuming various prey (Voris 1972).…”