This species is endemic to Sri Lanka, where is is know from the eastern intermediate zone (Fernando et al., 2007). It has so far been recorded from Kokagala Hill, in Ampara district, Eastern Province, and from Yakunhela, near Bibile, Monaragala District, Uva Province (Fernando et al., 2007). All records are from between 200 and 620m asl (Fernando et al., 2007). Although might be discovered in future in other locations, many of the hill tops in eastern Sri Lanka, including Monaragala, have been searched for this species without success (S. Fernando pers. comm.).
Habitat and Ecology
This species is associated with seasonal streams with rock crevices on hillsides with scattered trees, and a ground cover of grasses, dominated by Cymbopogon sp. (Fernando et al., 2007). Rock crevices, boulders, masses of grass (Cymbopogon sp.), and roots and vegetation mats consisting of Utricularia, Eriocaulon and Xyris spp. have been identified as microhabitats (Fernando et al., 2007). The vegetation and the water sources rapidly dry out during the southwest monsoon winds in July-October, and bush fires are frequent at this time of year (Fernando et al., 2007). The new species is more active at night; during the day it hides in the microhabitats (Fernando et al., 2007). In the morning, individuals gather on the open vegetation mats of Utricularia to prey on insects attracted by flowers (Fernando et al., 2007). The tadpoles presumaly live of wet rock surfaces by streams, like other members of the genus. The species has a short annual activity period (December-February), after which the habitat dries out and the frogs hide underground (perhaps in deep rock crevices) (S. Fernando pers. comm.). In anthropogenic habitats within its range, the landscape modifications (such as slash-and-burn cultivation) result in a very low water-retaining capacity in the ground, and so it is thought that the species cannot survive in such areas (S. Fernando pers. comm.).
It is quite common at its two known locations. Populations are aggregated, with 10-15 individuals being found along a 10m length of a seepage stream (S. Fernando pers. comm.). There are certainly more than 100 mature individuals in each of its known locations (S. Fernando pers. comm.).
The species is threatened by removal of the natural vegetation for agriculture, including slash-and-burn cultivation (S. Fernando pers. comm.). Human activities are increasing on the hill tops on which it occurs, with burning of the grassland, and felling of trees (S. Fernando pers. comm.). All of these activities reduce the water-retention capacity of the small streamlets (S. Fernando pers. comm.). It might also be impacted by high agrochemical usage (S. Fernando pers. comm.).
It occurs in the Kokagala Forest Reserve (Fernando et al., 2007), but active conservation measures now need to be targeted towards securing the survival of this species in both of the sites in which it occurs. Surveys are needed to determine more accurately its distribution, ecological requirements and conservation needs.
Samantha Fernando 2008. Nannophrys naeyakai. In: IUCN 2014