This species is currently known from approximately 330–1,220 m Asl in southern China (Fei et al. 2012), northern Thailand (Chan-ard 2003), northern to central Viet Nam (Boulenger 1903, Inger et al. 1999, Orlov et al. 2002, Bain et al. 2007, Nguyen et al. 2009), and eastern Cambodia (Stuart et al. 2010). These are unlikely to represent the actual limits of the species' range as similar habitat and elevations to those in the species' known localities extend into parts of intervening Laos and a small section of extreme-eastern Myanmar. Further surveys in these areas may uncover its presence, therefore its range has been projected beyond known sites to include these areas of suitable habitat. The species' extent of occurrence (EOO) is 1,857,093 km2.
Habitat and Ecology
This species is associated with hilly evergreen forest and has mostly been observed adjacent to steep, rocky streams on rocks and branches (Inger et al. 1999, Stuart et al. 2006). Individuals have also been observed around swampy areas (Inger et al. 1999). Breeding occurs in streams by larval development (Inger et al. 1999, Stuart et al. 2006, Handrigan et al. 2007). In southern Viet Nam calling males with nuptial pads have been observed during April (Inger et al. 1999), and pairs have been observed in amplexus during October in eastern Cambodia (Stuart et al. 2006).
The size of this species' population is not well known, however it has been detected in a number of surveys (e.g. Boulenger 1903, Inger et al. 1999, Orlov et al. 2002, Chan-ard 2003, Bain et al. 2007, Nguyen et al. 2009, Stuart et al. 2010, Fei et al. 2012), and large numbers were observed in the southern part of its range during the breeding season in 1995 (Inger et al. 1999). It is likely that ongoing forest loss associated with expanding agriculture throughout the species' range (Meyfroidt and Lambin 2008, Sodhi et al. 2009, Meyfroidt et al. 2013) is causing some population declines.
Habitat loss and degradation due to rapidly expanding agriculture is an ongoing threat to biodiversity throughout Southeast Asia (Sodhi et al. 2009). In the Central Highlands of Viet Nam large areas of forest are converted to agricultural land to grow cash crop plantations (e.g. rubber, coffee and tea) (Meyfroidt and Lambin 2008, Meyfroidt et al. 2013). Throughout Thailand the widespread cultivation of oil palm has been implicated as a major driver of forest loss (Sodhi et al. 2009). High rates of deforestation for logging, and agricultural encroachment on natural forest are also ongoing in much of Laos and Cambodia (Sodhi et al. 2009). Other causes of habitat degradation in eastern Cambodia are increasing human settlement and the development of large hydroelectric dams, both of which are ongoing within protected areas (Ohler et al. 2002, Grimsditch 2012). This species is very likely threatened to some degree by habitat loss.
This species is known from a number of protected areas including Virachey National Park in Cambodia (Stuart et al. 2010). A considerable number of other protected areas are included in parts of this species' predicted range; it very likely occurs in some of these also.
In order to ensure the species' long-term survival, the lack of data must be addressed; research should be carried out to determine its relative abundance and threats.
Red List Status
Least Concern (LC)
Listed as Least Concern in view of its wide distribution and presumed large population.
We follow Ohler (2003) in considering Ophryophryne poilani to be a junior synonym of O. microstoma.
IUCN SSC Amphibian Specialist Group 2017. Ophryophryne microstoma. The IUCN Red List of Threatened Species 2017: e.T57586A113959447. http://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T57586A113959447.en .Downloaded on 19 January 2019