Species level taxonomy and endemism
The detailed morphological and molecular evidences from our study successfully resolved many taxonomic ambiguities and distribution limits of several nominal taxa in the genus Hylarana. These include species that have long been misidentified, or are currently considered as synonyms. Confirmed endemicity of H. aurantiaca and H. temporalis based on our results is interesting given that these two species have been known for more than 100 years (H. aurantiaca), up to nearly 150 years (H. temporalis). While H. aurantiaca is endemic to the vicinity of its type locality in the Western Ghats, H. temporalis is endemic to Sri Lanka. The small-sized Hylarana in Sri Lanka belong to a previously unnamed species H. serendipi and ‘Hylarana temporalis’ populations from India comprise of a complex of two named (H. flavescens and H. montanus) and four previously unnamed species (H. caesari, H. indica, H. magna and H. sreeni). Hylarana flavescens, H. intermedius and H. montanus are resurrected from the synonymy of H. temporalis and considered as valid species. Rana (Hylorana) bhagmandlensis is removed from the synonymy of H. aurantiaca, and regarded as a junior subjective synonym of H. montanus. In the interest of nomenclatural stability, Rana flavescens, Rana malabarica and Hylorana temporalis are lectotypified, and a neotype is designated for Rana (Hylorana ) intermedius. Hylarana malabarica, which was originally described from the southern Western Ghats is suggested to possibly represent at least two genetically distinct morphologically cryptic species. For taxonomic remarks on all Hylarana species of the Western Ghats and Sri Lanka, see individual species accounts in the Appendix.
Our data suggests that many species have a narrow latitudinal range, especially H. temporalis and H. aurantiaca, which were previously considered as the most widely distributed taxa. The consensus of all our analyses is a trichotomy of four major lineages within the study area: 1 — the Hylarana aurantiaca group, is one that gave rise to a clade of species mostly restricted to south of the Palghat Gap, except for the distribution of H. intermedius which is only found north of the Palghat Gap (Fig. 10); 2 — the Hylarana flavescens group, is widely distributed along the entire Western Ghats, but has restricted distribution ranges at species level. Hylarana sreeni is the only species found both north and south of the Palghat gap. Hylarana magna is restricted to the Agasthyamala hill range south of the Palghat gap, while H. flavescens, H. indica and H. montanus are only found north of the gap. Furthermore, H. caesari is restricted to the northern Western Ghats of Maharashtra (Fig. 14). 3 — the Hylarana temporalis group is a radiation endemic to Sri Lanka. Hylarana temporalis is widely distributed on the island and occurs both at mid elevation (up to about 900 meters) and in the wet zones of Sri Lanka. This group also contains a previously unnamed species, H. serendipi, which is endemic to, and found sympatrically with H. temporalis in the wet zone of Sinharaja World Heritage Site, Sri Lanka (Fig. 20). 4 — the Hylarana malabarica group forms a distinct, well supported clade containing one peninsular Indian (H. malabarica) and one Sri Lankan (H. gracilis) species (Fig. 24). Though H. malabarica is considered to be widely distributed, our study finds genetic segregation between the populations found in northern (Hylarana malabarica haplogroup 1) and southern parts of the Western Ghats. Based on molecular evidence, we confirm the extended occurrence of Hylarana malabarica haplogroup 1 populations from the northern Western Ghats, east to Madhya Pradesh state. Hylarana gracilis is the most widely occurring among Sri Lankan Hylarana species, which is endemic to Sri Lanka and found from sea level to 1250 m elevation.