Middle Miocene biogeographic connectivity between the Eastern Ghats and Nepal revealed by a new species of the Cyrtodactylus (Geckoella) nebulosus complex (Reptilia, Squamata) from Nepal

A new species of ground-dwelling gecko of the genus Cyrtodactylus (Geckoella) is described from the low elevation Terai-Duar region of southeastern Nepal using molecular and morphological data. Cyrtodactylus teraiensis sp. nov. is the first new species of the C. nebulosus species complex, the remaining members of which are distributed in the northern Eastern Ghats and Satpuras; a lectoype for C. nebulosus is also designated. The new species is the first Geckoella described from outside peninsular India and distributed north of the Indo-Gangetic Plains. Cyrtodactylus teraiensis sp. nov. forms the deeply divergent sister taxon to Indian members of the C. nebulosus complex with 15.7–18.1% uncorrected mitochondrial sequence divergence from them, and 21.0–28.5% from other Geckoella. The new species is also recognised in tree-based delimitation methods and can be morphologically distinguished from other Cyrtodactylus and Geckoella species by a small body size (snout to vent length, SVL up to at least 45.5 mm), length of original tail < SVL, 16–18 rows of dorsal tubercles, 30–32 ventral scales across belly at midbody; dorsal colour pattern of four or five paired spots between neck and hindlimb insertions alternating with two or three much smaller paired spots. The divergence between Cyrtodactylus teraiensis sp. nov. and Indian members of the C. nebulosus complex is estimated to have occurred in the Middle Miocene, and it may be that tropical forest expansion during the Mid-Miocene Climatic Optimum allowed dispersal across the Indo-Gangetic Plains.