Waterfall frog

Description

The waterfall frog is large in size, reaching 5.5 cm in length. The dorsal surface is mottled with puck brown. The patterning on the back is similar to its habitat, allowing for effective camouflage against granite. The ventral surface is bright orange, green, and pink in colour, and granular. The posterior ventral surface is translucent, showing internal parts.

The toe pads of R. nannotis are very large in comparison to toe width, to aid in gripping to rocks in the rapids. The nuptial pads of breeding males are also large, covering the entire inner surface of the thumb, with spines also present on the arms and chest. The tympanum is not visible, the fingers are partially webbed, and the toes are completely webbed.

Like the stoney creek frog (Litoria wilcoxi), and many other stream-dwelling frogs, waterfall frogs lack vocal sacs. This may be because the sound of a running stream drowns out any calls, and it becomes a waste of energy.

Ecology and behavior

The waterfall frog is a stream-dwelling frog native to tropical north Queensland, from Paluma to Cooktown, notable in the Mt. Carbine uplands. It is found at altitudes between 180 and 3,000 m (590 and 9,840 ft). It has undergone large declines in high-altitude areas (likely from chytridiomycosis), with many populations completely extinct. It is, however, stable in lowland areas.

Conservation status

It is listed as Endangered under both the IUCN Red List and Queensland's Nature Conservation Act 1992.