Four in one: An integrative taxonomic revision of the Microhyla berdmorei complex (Amphibia: Anura: Microhylidae) illustrates the tremendous amphibian diversity of Southeast Asia

Abstract

Abstract Berdmore’s narrow-mouthed frog, Microhyla berdmorei (Blyth, 1856), is the largest member of the genus Microhyla and is distributed all over Southeast Asia, from Northeast India and southern China to Sumatra and Borneo in Indonesia. Here we demonstrate that M. berdmorei represents a complex of four species that are morphologically, acoustically, and genetically distinct from each other, and we implement taxonomic revisions. Phylogenetic analyses of three mitochondrial DNA (hereafter mtDNA, including COI, 12S, and 16S rRNA; 3119 bp) and one nuclear (BDNF; 716 bp) gene sequences are corroborated by phylogenomic analyses of 2700 ddRAD-seq loci (387,270 bp). All support that the M. berdmorei complex, which originates from the early Miocene (ca. 19.7 mya), consists of two clades that we date to the late Miocene (ca. 7.5 mya). The first clade, which regroups populations of large-sized individuals, is distributed in Indo-Burma and includes a lineage from Northeast India, Bangladesh, and Myanmar (M. berdmorei sensu stricto) and a lineage from West Malaysia, Thailand, Laos, Cambodia, and Vietnam (for which we propose to resurrect the species M. malcolmi Cochran, 1927). The second clade, which regroups populations of small-sized individuals, occurs in Sundaland and also includes two lineages for which we provide taxonomic descriptions on species rank. The first new species is widely distributed from Peninsular Malaysia to the islands of Borneo and Sumatra (described herein as M. sundaica sp. nov.), while the second one is restricted to the Malay Peninsula and occurs in extreme southern Thailand and adjacent Malaysia (M. peninsularis sp. nov.). We further provide evidence for the synonymy of Callula natatrix Cope, 1867 with M. berdmorei sensu stricto, and M. fowleri Taylor, 1934 with M. malcolmi. Our study illustrates the high diversity of Southeast Asian amphibians, especially in the genus Microhyla, which presently totals 54 species.