Frankixalus, a New Rhacophorid Genus of Tree Hole Breeding Frogs with Oophagous Tadpoles

Abstract

Despite renewed interest in the biogeography and evolutionary history of Old World tree frogs (Rhacophoridae), this family still includes enigmatic frogs with ambiguous phylogenetic placement. During fieldwork in four northeastern states of India, we discovered several populations of tree hole breeding frogs with oophagous tadpoles. We used molecular data, consisting of two nuclear and three mitochondrial gene fragments for all known rhacophorid genera, to investigate the phylogenetic position of these new frogs. Our analyses identify a previously overlooked, yet distinct evolutionary lineage of frogs that warrants recognition as a new genus and is here described as Frankixalus gen. nov. This genus, which contains the enigmatic ‘Polypedates’ jerdonii described by Günther in 1876, forms the sister group of a clade containing Kurixalus, Pseudophilautus, Raorchestes, Mercurana and Beddomixalus. The distinctiveness of this evolutionary lineage is also corroborated by the external morphology of adults and tadpoles, adult osteology, breeding ecology, and life history features.

Redescription and geographic distribution of Raorchestes shillongensis (Anura: Rhacophoridae) from Meghalaya, Northeast India

“…Northeastern Indian anurans are poorly known, as evidenced by the numerous discoveries of new amphibian species in the last 5 yr (Mahony et al 2011, Sondhi and Ohler 2011, Kamei et al 2012, Purkayastha and Matsui 2012, Das et al 2013, Biju et al 2016. Of the 62 species of Raorchestes, 45 have been described in the last 15 yr.…”

“…Our frogs from the south (Riwai and Mawlynnong) and from et al (2016) who showed that R. shillongensis is closely related to the Indochinese subclade of Raorchestes, rather than the clades of the Western Ghats (Raorchestes) and Southeast Asian (Philautus). Though Northeast India is a major center of amphibian diversity, only the caecilian fauna of this region has been studied phylogenetically (Kamei et al 2012, Biju et al 2016. Moreover, rhacophorid frogs of Northeast India have received little attention in contrast to the members of this family in the Western Ghats.…”

Comparative Postembryonic Skeletal Ontogeny in Two Sister Lineages of Old World Tree Frogs (Rhacophoridae: Taruga, Polypedates)

“…These new generic descriptions are largely based on molecular data and to a lesser extent on molecular data and morphology [13,14,16]. One of the main impediments to new lineage identification, prior to the advent of molecular phylogenetic techniques, was the lack of consistent external morphological characters.…”

“…One of the main impediments to new lineage identification, prior to the advent of molecular phylogenetic techniques, was the lack of consistent external morphological characters. In recent phylogenetic reconstructions of rhacophorid relationships, adult skeletal data have been sparsely used [13,14], but never skeletal ontogeny.…”

“…Finally, foam-nesting genera are in two paraphyletic clades ( Rhacophorus , Polypedates , Taruga , Ghatixalus in one clade and Chiromantis as another). These have terrestrial foam nests and postembryonic free-swimming tadpoles [2,5,6,13,15]. Skeletal ontogeny across developmental stages of these forms is not known, except for a single study on Pseudophilautus silus [17].…”