A new species of the poorly known genus Colubroelaps Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009, is described based on a single female specimen collected from Hon Tre Island, Khanh Hoa Province, Vietnam. The new species, Colubroelaps adlerisp. nov., can be distinguished from its sister species Colubroelaps nguyenvansangi Orlov, Kharin, Ananjeva, Nguyen & Nguyen, 2009 by the following combination of morphological characters: small body size (TL 402 mm); tail relatively short (ratio TaL/TL 0.10); dorsal scales in 14–14–14 rows; supralabials six, third and fourth entering orbit; infralabials seven; loreal present; ventral scales 234; subcaudals 30, all divided; cloacal plate divided; dorsal coloration pale brown, with narrow and interrupted dark stripe along spine; body flanks dark-gray lacking bluish iridescence; ventrally uniform off-white; head black with rostral, nasals, prefrontals, preoculars, loreal, and the two anterior supralabials, as well as anterior parts of supraoculars and frontal dirty yellowish-brown with dark-brown spots. This discovery represents the second known species of the genus Colubroelaps and the first record of the genus in the coastal areas of southern-central Vietnam. The new species is likely micro-endemic to the small island of Hon Tre within Nha Trang Bay in Khanh Hoa Province, Vietnam, at an elevation of 30 m a.s.l., and was recorded only from the heavily disturbed secondary forest area of the island. The new species is under threat due to the intensifying development of tourist infrastructure on Hon Tre Island. We suggest that the new species be considered Endangered (EN) following the IUCN’s Red List categories.
