Unnoticed for a Century and a Half: Bornean Leaf Litter Frog, Leptobrachella gracilis, is Not a Single Species (Anura, Megophryidae)

A Bornean megophryid, Leptobrachella gracilis (Günther, 1872), the type species of now synonymized genus Leptolalax, proved to contain two different call types that differ in various aspects of advertisement calls including pulse repetition rate and dominant frequency. Genetic analyses of mtDNA and nuDNA of these two types (slow- and fast-call) co-occurring at the type locality, Matang, Sarawak, revealed them to be heterospecific with no evidence of gene exchange. The female holotype of L. gracilis is estimated to belong to the slow-call type based on morphological similarities. We therefore describe the fast-call type as a new species, Leptolalax sarawakensis sp. nov.