New frog family from India reveals an ancient biogeographical link with the Seychelles

Abstract

About 96% of the more than 4,800 living anuran species belong to the Neobatrachia or advanced frogs. Because of the extremely poor representation of these animals in the Mesozoic fossil record, hypotheses on their early evolution have to rely largely on extant taxa. Here we report the discovery of a burrowing frog from India that is noticeably distinct from known taxa in all anuran families. Phylogenetic analyses of 2.8 kilobases of mitochondrial and nuclear DNA unambiguously designate this frog as the sister taxon of Sooglossidae, a family exclusively occurring on two granitic islands of the Seychelles archipelago. Furthermore, molecular clock analyses uncover the branch leading to both taxa as an ancient split in the crown-group Neobatrachia. Our discovery discloses a lineage that may have been more diverse on Indo-Madagascar in the Cretaceous period, but now only comprises four species on the Seychelles and a sole survivor in India. Because of its very distinct morphology and an inferred origin that is earlier than several neobatrachian families, we recognize this frog as a new family.

Global patterns of diversification in the history of modern amphibians

“…Our timetree gains credibility from its congruence with previous relaxed-clock studies based on nuclear sequences or combined nuclear plus mitochondrial data sets for smaller taxon samples, or focusing on restricted parts of the amphibian tree (19,20,23,24,26,30,31). Our estimates are particularly in line with the results of San Mauro et al (19), inferred from RAG1 sequences of 44 taxa.…”

“…1a). They place the early diversification of the three modern orders in the Triassic/early Jurassic, of Natatanura [Ranidae sensu (26,27)] and Microhylidae in the late Cretaceous, and of the primarily South American Nobleobatrachia [Hyloidea sensu (19,30,32)] around the Cretaceous-Tertiary boundary. The two most species-rich salamander families, Plethodontidae (mainly North American) and Salamandridae (mainly Eurasian), were also found to have undergone most of their early diversification in the Tertiary, although the Bayesian dating method and PL analyses alternatively supported late Cretaceous or early Tertiary origins for their initial splits (SI Data Set 1).…”

Vast underestimation of Madagascar's biodiversity evidenced by an integrative amphibian inventory

“…An important acceleration in the rate of new discoveries, mainly from tropical areas, is obvious from many recent studies (11)(12)(13)(14)(15)(16). These discoveries are not the result of taxonomic inflation (9,14,17), but correspond to real divergent species (18,19). Although high numbers of undescribed amphibians have been estimated to exist in poorly studied tropical regions (11,15), these results remain unverified for complete, highly diverse amphibian faunas.…”

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

“…This region has gone through a long period of insularity during its northward drift towards Asia from Africa [26]. There is growing evidence that a number of Gondwana relicts are distributed in the Western Ghats and Sri Lanka [27] with considerable endemism among disparate taxa [25,[28][29][30]. However, these high levels of endemism and diversity remain unexplained.…”