REPRODUCTION AND TERRRESTRIAL DIRECT DEVELOPMENT IN SRI LANKAN SHRUB FROGS (RANIDAE: RHACOPHORINAE: PHILAUTUS)

Abstract

Two distinct nesting behaviours are reported from 98 clutches (80 in situ and 18 ex situ) of 17 species of direct-developing Philautus from Sri Lanka. The species examined, belong to three communities spanning 400-2,200 m elevation. Sixteen species are 'ground nesters', depositing 6-155 cream or white eggs in 5-35 mm deep nests excavated by the female in the rainforest floor. This is the first record of terrestrial egg burying in soil by the direct-developing anurans, a behaviour commonly employed by tetrapod reptiles. A single species (Philautus femoralis) however, is an arboreal nester, depositing 7-22 green, adhesive eggs in a disc-like mass on the underside of leaves. Parental care is not provided by any of the species. Larval development in Philautus differs from the Neotropical direct-developing leptodactylid, Eleutherodactylus coqui: the former lack external gills and have a rudimentary cement gland, a coiled gut and a larger, spatulate, heavily vascularized tail. They also lack an egg tooth. The first two of these apparently primitive characters have so far been observed only in aquatic anuran tadpoles and not in direct-developing larvae. Furthermore, the Philautus larvae studied possess atrophied internal gills, respiration apparently being facilitated primarily via the tail.