This species is one of the rarest and most ancient frogs in the world. It was originally found on both the North and South Island of New Zealand, but its range was reduced to a 600 m sq. boulder bank near the summit of Stephens Island. It is a ground-dwelling and night-active species that hides in damp, mossy rock crevices during the day. Males guard the nesting site and carry the newly hatched young on their backs. Despite being less than 50 mm long, it is New Zealand’s largest native frog. It is threatened by its tiny range and small population, introduced and native predators, and potentially a virulent fungal disease (chytridiomycosis).