Description

Nannophrys naeyakai are flat bodied frogs with an average length from snout to vent of 39.30 mm. Adult males vary in snout-vent length between 24.35 to 35.90 mm and adult females are typically between 29.50 and 43.60 mm. Females on average tend to be slightly larger with an average snout to vent length approximately 5 mm larger than males. The species have a rounded snout that is greater in its width than length, resulting in a broad head shape. Their nostrils are positioned on the tip of the snout and are dorsally flush (not elevated from the head), while the lore is slightly concave. The tympanum has a rounded shape with a horizontal diameter that is equivalent to half of the orbit diameter. A fold beneath the tympanum is visible and extends from behind the eyes to the base of the front legs. All finger and toe digits are rounded. The hind digits do not have any webbing. Nannophrys naeyakai have a distance of about 1.05 mm between the distal subarticular tubercle and penultimate subarticular tubercles on the 4th toe. Tubercles are present on the dorsal portions of the head, shoulder, and legs in a scattered pattern (Fernando et al. 2007).

Nannophrys naeyakai can be differentiated from other species by a variety of characters. Nannophrys naeyakaihas a larger distance between the distal and penultimate subarticular tubercles than the distance between the tubercles of the N. marmorata. Nannophrys naeyakai has a narrow symphyseal knob and two sharp apophyses upon the jaws anterior portion. The height of the symphyseal knob is lower than the apophyses when compared to N. marmorata, whose wider symphyseal knob height is equal or slightly taller than its wide apophyses. Nannophrys naeyakai has opaque yellow stripes on the hind legs that align when the legs are folded in position next to the body. Nannophrys marmorata lacks this striped pattern and has a marbled pattern instead. Nannophrys ceylonensis and N. guentheri however, lack the dorsal marbled pattern completely. The distance between the tympanum and eye is much smaller in N. naeyakai in comparison to N. ceylonensis (Fernando et al. 2007).

Body color in life, is dark brown with opaque yellow spots. There are yellow opaque stripes that run across the legs in a perpendicular direction to the body. There is one stripe on the upper and lower portion of the forearm, and three stripes that run across the hind legs. When N. naeyakai has its legs folded near the body these stripes align with one another. The ventral side is a yellow opaque color and does not possess any markings (Fernando et al. 2007).

There is no sexual dimorphism between male and female specimens (Fernando et al. 2007).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Sri Lanka

View distribution map in BerkeleyMapper.

Nannophrys naeyakai is endemic to the Nilgala Forest of the Monaragala District of Sri Lanka and Kokagala, Padiyatalawa of the Ampara District. The main habitat of N. naeyakai includes seasonal streams with rugged crevices, rock pools and/or boulders covered in matted foliage (Fernando et al. 2007). They can be found at an elevation range from 200 m to 700 m (Karunarathna et al. 2008). In a distribution study of amphibian fauna of Sri Lanka, N. naeyakai was found to be most abundant in wet zone highland and lowland ranges. The wet zones were classified as areas that received on average greater than 2000 mm of precipitation a year (Surasinghe 2009).

Life History, Abundance, Activity, and Special Behaviors

Nannophrys naeyakai are more active at night than during the day. These frogs are only active for the short rainy season between December and February, when they live among horizontal rock crevices near clear water streams due to the streams being seasonal. Outside of the rainy season the species retreats underground (Fernando et al. 2007).

Trends and Threats

Nannophrys naeyakai was described as a new species in 2007 and classified as “Endangered” on the IUCN Red List shortly after. The new species of rock frog is native to the eastern intermediate zone of Sri Lanka, where its abundance is restricted to fewer than five locations that, when combined, cover 5000 km² (Fernando et al. 2007). All geographical locations are experiencing a continued decline in population numbers. Populations are aggregated, with an average of 12 frogs found along a 10 m stretch of flowing water (Fernando 2008).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Disturbance or death from vehicular traffic
Local pesticides, fertilizers, and pollutants

Comments
As of 2024, three other species belong to the genus Nannophrys: N. ceylonensis, N. ceylonensis N. marmorata. The genus Nannophrys used to be placed in the family Ranidae but a phylogenetic study using neighbor-joining analysis of mitochondrial 16S and 12S rNA DNA sequences determined that the genus belonged to the family Dicroglossidae (Vences et al. 2000).

References

Fernando, S, L.j., Wickramasingha, M., Rodirigo, R. (2007). ''A New Species of Endemic Frog Belonging to Genus Nannophrys Günther, 1869 (Anura: Dicroglossinae) from Sri Lanka.'' Zootaxa, 1403, 55-68.

Fernando, S. (2008). Nannophrys naeyakai. The IUCN Red List of Threatened Species 2008: e.T135839A4209157. Downloaded on 13 February 2017

Glaw, F., Schmidt, K., and Vences, M. (2000). ''Nachzucht, Juvenilfärbung und Oophagie von Mantella laevigata im Vergleich zu anderen Arten der Gattung (Amphibia: Ranidae).'' Salamandra, 36, 1-24.

Surasinghe, T. D. (2011). ''Conservation and Distribution Status of Amphibian Fauna in Sri Lanka.'' Biodiversity

Species Account Citation: AmphibiaWeb 2024 Nannophrys naeyakai: Sri Lanka Tribal Rock Frog <https://amphibiaweb.org/species/6888> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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