A new species of green rat snake (Squamata: Colubridae: Ptyas) from Vietnam

Rat snakes (genus Ptyas) include 13 large Asian species with sizes reaching 3.8 m. For more than 100 years, no new species have been discovered in this genus. Here, we describe a new Ptyas from central Vietnam based on morphological data and nucleotide sequences from the MT-CYB gene. Ptyas bachmaensis sp. nov. is diagnosed by the following morphological characters: large-sized snake (largest total length 2401 mm in adult male); body scale rows in even numbers, 16-16-14 rows; two medial vertebral scale rows distinct; two and two or four medial scale rows keeled on middle and posterior parts of body, respectively; ventrals 194–199; subcaudals 132–138; supralabials 8, fourth and fifth entering orbit; maxillary teeth 28 or 29; hemipenis spinose and unforked, reaching 12^th subcaudal; cloacal plate divided; lateral side of tail black, without a bright stripe. The new species forms an independent clade on the phylogenetic tree and differs from its congeners by an uncorrected p-distance in MT-CYB sequences of at least 5.7%.