Family- Ranidae (True Frogs)
There more than 400 species of ranids in the world in 23 genera (AmphibiaWeb). Ranidae is distributed throughout the world except Antarctica. They have smooth moist skin, distinct tympanum, powerful hindlimbs and webbed toes. This family includes small to large frogs (SVL 100mm). The pupil is horizontal in most ranids. Their amplexus is axillary. Most species have indirect development with a free living tadpole that has keratinous mouth parts.
Ranidae in Sri Lanka
The ranidae in Sri Lanka consists of only three species in the two genera Hydrophylax and Indosylvirana (Biju et al., 2014). These three species are characterized by their dorso-lateral ridge that runs along the body from snout to vent. They also possess round digital disks. All three species are closely associated with water.
Genus- Hydrophylax Fitzinger, 1843
A single species of Hydrophylax is recorded from Sri Lanka. The species can be distinguished from Indosylvirana species by the presence of a robust body, a granular skin in the posterior part of the abdomen and a thick and well developed dorsolateral fold.
Species of Hydrophylax in Sri Lanka
Hydrophylax gracilis (Gravenhorst, 1829)E
Hydrophylax gracilis can be distinguished from the other species of ranids in Sri Lanka by the presence of longitudinal stripes on the shank, weekly developed rounded digital disks and a bronze colour line extending from the end of the mouth to the groin. The species grows up to maximum Snout to vent length of 55 mm. It is a common species usually found in paddy fields, marshes, close to streams, lakes and ponds in the lowlands of Sri Lanka up to an elevation of 1200m above. m.s.l. Tadpoles of Hydrophylax gracilis is known from paddy fields of Sri Lanka (Ukuwela, 2009).
Genus- Indosylvirana Oliver, Prendini, Kraus, and Raxworthy, 2015
Two species of Indosylvirana are known from Sri Lanka. They are characterised by having granular or wrinkled skin in the posterior part of the abdomen, thin and well defined dorsolateral folds with a pale or similar colour.
Species of Indosylvirana in Sri Lanka
Indosylvirana serendipi Biju, Garg, Mahony, Wijayathilaka, Senevirathne and Meegaskumbura, 2014E
Indosylvirana temporalis (Günther, 1864)E
Indosylvirana temporalis can be differentiated from Indosylvirana serendipi from the robust body (vs slender body in Indosylvirana serendipi), presence of a supratympanic ridge (vs absence in Indosylvirana serendipi) and by the presence of distinct cross bands on the shank (vs faint bands in Indosylvirana serendipi) (Biju et al., 2014). Indosylvirana temporalis is found closed to water bodies in forested regions in the wet and intermediate zones of Sri Lanka (Dutta & Manamendra-Arachchi, 1996). Indosylvirana serendipi is known from the Southwest lowlands of Sri Lanka (Biju et al., 2014).
Abreviations in superscript
E- Endemic species, Ex- Extinct species, Cr- Critically Endangered species, En- Endangered species
References
Biju, S. D., S. Garg, S. Mahony, N. Wijayathilaka, G. Senevirathne, and M. Meegaskumbura. 2014. DNA barcoding, phylogeny and systematics of Golden-backed frogs (Hylarana, Ranidae) of the Western Ghats-Sri Lanka biodiversity hotspot, with the description of seven new species. Contributions to Zoology, 83: 269–335.
Dutta, S. K., and K. Manamendra-Arachchi (1996) The Amphibian Fauna of Sri Lanka. Wildlife Heritage Trust of Sri Lanka. Colombo.
Oliver, L., E. Prendini, F. Kraus, and C. J. Raxworthy. 2015. Systematics and biogeography of the Hylarana frog (Anura: Ranidae) radiation across tropical Australasia, Southeast Asia, and Africa. Molecular Phylogenetics and Evolution, 90: 176–192.
Ukuwela, K.D.B. (2009) Description of the tadpole of Hylarana aurantiaca (Anura: Ranidae) from Sri Lanka. Zootaxa, 2016: 67-68.