Snakes northern Thailand

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FOR A CHECKLIST of the more than eighty snake species that occur in Thailand, see Illustrated Checklist .
FOR A BRIEF introduction to the BIOLOGY OF SNAKES, click here .

SNAKE NEWS. The first half of this year’s rainy season, I was happy to spot quite a number of interesting snakes and to come across lots of road-killed snakes, among the latter specimens of at least two species that have not yet been recorded in Thailand before. I was also happy that an earlier ‘first country record for Thailand’ of mine (of a rare and rather strange-looking snake species) was reported in a herpetological journal, while an article on the resurrection of a snail-eating snake following a long delay in China, was finally edited very well and published in Tropical Natural History, one of the best and most professional English-language journals on biology published in Thailand. Some twenty species of snail-eating snake are known from South and Southeast Asia and southern China, and two of them are ornamented with bicolored (black-an-white) spots. Despite such a similar ornamentation, the two, Pareas macularius (left in the picture above) and Pareas margaritophores (right) show a large number of differences. Since their discoveries and first descriptions in the 1860s the two have lived peacefully together as apart species in the taxonomy. However, in a Chinese study that appeared in 2004, it was argued that the two were on and the same species, and, since Pareas margaritophorus was decribed in 1866, before Pareas macularius in 1868, the ‘nominal species’ Pareas macularius was considered as a junior synonym of Pareas margaritophorus, and eliminated as a valid species—as a big surprise to many herpetologists with were familiar with snail-eaters. My study on this topic was based almost completely on DORs (Death On Roads), road-killed specimens that I had collected all over northern Thailand. As snail-eaters are predominantly night-active animals, the freshest and most intact specimens could be found in the early morning. Following about two rainy seasons of intensively collecting DOR-snakes are had gathered more than enough evidence that there exist two distinct bicolored-spotted snail-eaters in Thailand of which one corresponds with Pareas margaritophorus, and the other with the ‘synonymized’ Pareas macularius. The summary of my resurrection of Pareas macularius as a valid species is given below:
The genus Pareas Wagler, 1830, consists of about fifteen species of small snail-eating snakes distributed in China, South and Southeast Asia. Until recently, two Pareas-species ornamented with characteristic bicolored spots were recognized, P. margaritophorus (Jan in Bocourt, 1866) and Pareas macularius Theobald, 1868. However, P. macularius was synonymized with P. margaritophorus by Huang (2004), reducing the speciosity of the bicolored-spotted snail-eaters to a single species. This claim was tested by examining more than 60 fresh road-killed specimens of bicolored-spotted snail-eaters from northern Thailand. They were either completely smooth-scaled, or had rows of weakly keeled dorsals. The smooth-scaled specimens differed significantly from the keeled-scaled in a number of characters. The holotype of P. margaritophorus corresponded closely to the smooth-scaled specimens, whereas the holotype of Pareas macularius corresponded to the keeled-scaled ones. It was, thus, shown that P. macularius is a valid species and the synonymization as claimed by Huang (2004) was refuted. P. macularius is distinguished from P. margaritophorus by having the 7–13 most median rows of dorsal scales feebly keeled at midbody, by the form and color of the nuchal collar, its larger size, the larger number of ventral shields, and the high incidence of an intense black blotch on the last, largest supralabial. A preliminary distribution map for the two species is provided.
The complete article is: Sjon Hauser, 2017. On the validity of Pareas macularius Theobald, 1868 (Squamata: Pareidae) as a species distinct from Pareas margaritophorus (Jan in Bocourt, 1866). Tropical Natural History, 17(1): 147-174. A pdf can be downloaded from the journal’s website:  click here .