Integrative taxonomic analysis reveals a new species of Leptobrachium Tschudi, 1838 (Anura, Megophryidae) from Bangladesh

We report on a new species of frogs of the genus Leptobrachium from Lawachara National Park, Moulvibazar District, Sylhet Division in northeastern Bangladesh, based on molecular, morphological and bioacoustic evidence. Leptobrachium sylheticum sp. nov. is to date reliably known only from Sylhet Division of Bangladesh and Tripura State of India. The new species belongs to the L. smithi complex within the subgenus Leptobrachium and based on phylogenetic analyses of 16S rRNA mtDNA gene is suggested as a sister lineage to the clade comprised L. smithi and L. rakhinense. The new species can be distinguished from all other congeners by the following combination of characters: adult SVL of 50.2-60.9 mm in males, 63.9-68.3 mm in females; digit tips rounded; relative finger lengths: II<I< IV<III; relative toe lengths: V < I = II<III<IV; toe webbing formula: I 1-1 II 1-2 III 1-3 = IV 31/2 =-1 V; inner metatarsal tubercle large; iris bicoloured, black ventrally, red dorsally, sclera bright-blue; dorsum grey with few small black spots laterally, dark head markings indistinct; belly and limbs ventrally dark-grey to black with sparse whitish marbling on chest and belly and characteristic orange-red dots on ventral surfaces of lower jaws and gular area; dark marking covering the entire tympanum; dark canthal stripe narrow; dark spots or blotches on body flanks absent or small, not forming a row; limbs dorsally with 2-3 dark markings not forming complete transverse bars; dark blotch at groin absent, posterior sides of thighs blackish with white spots; femoral gland in shape of small white blotch; axillary gland as a large roundish blotch; males with single vocal sac, lacking spinules on lips during breeding; and an advertisement call consisting of 3-8 notes and a dominant frequency of 1.4-1.9 kHz (at 31.0 degrees C). Our study provides further evidence for still unrecognised amphibian diversity in Bangladesh.