This species is known only from five sites on Penang Island, off the northwest coast of Peninsular Malaysia. The current known altitudinal range is from sea level (D. Belabut pers. comm. January 2018) up to 700 m asl (Quah et al. 2011, E. Quah pers. comm. January 2018). This species is likely to be found more widely in forested habitat in pristine streams (Malaysia Red List Assessment Workshop January 2018). Its extent of occurrence (EOO) is 41 km2.
Habitat and Ecology
This is a stream-breeding species that inhabits rocky and fast flowing streams and leaf litter in rainforests. Like in the other species of the same genus, its tadpoles are equipped with oral suckers for clinging onto rocks to cope with the fast water flow (Quah et al. 2011). It is not thought to be tolerant to habitat degradation (Malaysia Red List Assessment Workshop January 2018).
The collection of tadpoles on Penang Hill in 2004 represented the first records of the species in over 100 years. Between 2009 and 2010, three subadult specimens were collected from the same area and more tadpoles observed (Quah et al. 2011). This scarcity of earlier records might be a reflection of the secretive nature of this species and inadequate surveying effort. It is considered to be an uncommon species (Malaysia Red List Assessment Workshop January 2018).
The forest habitat is that this species has been recorded from is relatively intact and there is not thought to be any major threats affecting it (Malaysia Red List Assessment Workshop January 2018).
The hill forests on Penang Hill are currently protected as a catchment area for Georgetown, and the lower reaches are within the Penang Botanical Gardens. The estimated range of this species encompasses Teluk Bahang Forest Reserve and Penang National Park, which are all well protected (Malaysia Red List Assessment Workshop January 2018). No conservation actions are currently in place for this species.
Studies on its population status, life history and ecology are needed. Monitoring of this species should be continued, given that it occurs in a localised area on an island (Malaysia Red List Assessment Workshop January 2018).
Red List Status
Listed as Least Concern since, although its extent of occurrence (EOO) is 41 km2, it occurs in an area of extensive, suitable habitat which appears not to be under significant threat.
Records of this species from Sumatra, Indonesia were previously assigned to Ansonia glandulosa (Iskandar and Mumpuni 2004). Subopulations that have been assigned to this species on the Isthmus of Kra and from Fraser's Hill in Malaysia are considered here to refer to A. malayana, a position which is supported by Grismer (2006) (who treats A. penangensis as endemic to Penang island). However, it is not clear that these two species are distinct from each other, and further taxonomic work is needed.
This is a restricted concept of this species following the split of the broader concept into this and Ansonia jeetsukumarani (Wood et al. 2008).
IUCN SSC Amphibian Specialist Group 2018. Ansonia penangensis. The IUCN Red List of Threatened Species 2018: e.T54479A3015679. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T54479A3015679.en .Downloaded on 19 February 2019