ANSONIA INFERNALIS 2022

The Thai-Malay peninsula contains a range of “sky islands” –isolated mountain habitats rising from a sea of very diferent lowland environments. These sky islands are rich in endemic species – like this species of stream toad, found on the lower slopes of the Nakhon Si Thammarat mountain range.

It has been named A. infernalis – infernal stream toad – for the bright reddish orange coloration of its limbs and fanks, said to resemble the fames of hell. The Latin adjective infernalis also means “lower”, referencing the lower elevations at which the species is found, between 300m and 900m above sea level.

The tiny toad – females are just 29mm long and males less than 25mm – was recorded at two locations 15km apart, in small, fast-fowing streams within evergreen forest. During the evening, the toads were observed slowly moving along the stream, or calling while perched on stones and leaves near the water. In the daytime, they could be seen sitting on rocks near the stream. Little is known about their natural history, but like some other stream toad species their behaviour appears to be seasonal.

As well as noting diferences in anatomy and colouration, researchers used molecular evidence to confrm that A. infernalis is a distinct species from other stream toads in the region. They described its discovery as “more of an expectation than a surprise” because of the rich diversity of range-restricted endemic amphibians and reptiles in this sky island archipelago. The discovery further underscores the rich unexplored biodiversity of the region and the need for conservation.

Suwannapoom, C., Grismer, L.L., Pawangkhanant, P. and Poyarkov, N.A. (2022). A new species of stream toad of the genus Ansonia Stoliczka, 1870 (Anura: Bufonidae) from Nakhon Si Thammarat Range in southern Thailand. Zootaxa 5168(2): 119-136. doi.org/10.11646/zootaxa.5168.2.2