This species is known from five locations in Thailand: Tasan (in Chumphon Province); Mamoh and Khlong Naka Wildlife Sanctuary (in Renong Province); Khlong Saeng National Park (in Surat Thani Province); and Khaolak Lamru National Park (in Phagnga Province), near the Isthmus of Kra. One recent record is from Tong Pha Phume in Kanchanaburi Province further north in western Thailand (Wichase Khonsue pers. comm.). Possible records from Phuket (P. van Dijk pers. comm.) remain to be verified. It probably occurs in southern Tenasserim (Myanmar), but this has not yet been confirmed. It has been recorded at around 1,000m asl.
Habitat and Ecology
It lives in primary rainforest near streams. It has also been observed on near-vertical bedrock in the spray zone of rainforest waterfalls. It presumably breeds by direct development, like other members of its genus.
It is an uncommon species.
The major threat is loss of forest habitat due to subsistence wood collection, agriculture, and human settlement.
It occurs in Khlong Naka Wildlife Sanctuary, Khlong Saeng Wildlife Sanctuary and Khaolak Lamru National Park. The species is fully protected from exploitation under Thailand's WARPA law.
Red List Status
Listed as Vulnerable, because its Extent of Occurrence is less than 20,000 km2 and its Area of Occupancy is less than 2,000 km2, its distribution is severely fragmented, and there is a continuing decline in the extent and quality of its habitat in southern and western Thailand.
Yodchaiy Chuaynkern, Wichase Khonsue, Tassanee Eamkamon 2004. Alcalus tasanae. The IUCN Red List of Threatened Species 2004: e.T41240A10422341. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T41240A10422341.en .Downloaded on 15 November 2018