Sibling species in South Indian populations of the rufous horse-shoe bat Rhinolophus rouxii

Cryptic species are difficult to identify using morphological identification tools. They represent hitherto unknown biodiversity and their discovery helps formulate more efficient conservation management policies. In this study we assess intraspecific diversity of Rhinolophus rouxii and investigate the presence of cryptic lineages. We characterize acoustic, morphological and genetic differences between allopatric populations of this species in Southern India. Our results reveal the presence of two distinct acoustic lineages (80 and 90 kHz phonic types). Forearm length also differs significantly between the two phonic types. They share a sister taxa relationship and the average genetic distance between them is over 8 %. Phylogenetic reconstruction and the associated divergence time suggest an evolutionary history that correlates with a middle Miocene separation. We propose that these two phonic types be called sibling species and evolutionarily significant units (ESU) within the subgenus Indorhinolophus. We recommend a new name, R. indorouxii for the species representing the 90 kHz phonic type. This study reiterates our lack of accurate taxonomic knowledge of bats, and highlights the value in combining genetics with behavioral (phonic characterization) and morphological measurements in the discovery of cryptic species.