Amolops siju

Amolops siju, the Siju Cave frog, is a true frog found in Siju Cave in India. It is brown with green mottling and dark bands on the legs, and the underside is light with dark patches. Only four specimens have been collected: three females of 85-94 mm and one male of 63 mm in snout-vent length, a marked size difference between the sexes (Wikipedia, general species account).

It has been found only in Siju Cave, but it is hypothesised that the frogs migrate down there, since the limestone cave keeps a steady temperature and humidity that may attract a frog seeking warmth. The frog has no adaptations to cave life, which supports the idea that it might also be found outside the cave (Wikipedia, general species account).