Tiny new species of toadlet discovered in Brazil

It may look cute and shine a cool fluorescent orange, but a newly-identified species of frog in Brazil is highly poisonous, scientists reveal.

The frog, called Brachycephalus rotenbergae, is just under an inch in length but has enough poison, transmitted from glands in its skin, to make a human ill.  

It also has bony plates on its skull and back that glow green through the skin under ultraviolet (UV) light – but researchers aren't sure why. 

B. rotenbergae was discovered south of the Mantiqueira mountain range in the state of São Paulo, Brazil, in forest along Brazil’s Atlantic coast. 

It's a type of pumpkin toadlet (Brachycephalus ephippium), which is a group of related species of fluorescent, brightly-coloured frogs, similar in shade to the squash that gives it its name. 

Other frogs in the same genus carry an extremely dangerous poison in their skins called tetrodotoxins, and it's likely B. rotenbergae does as well. 

B. rotenbergae spends most of its time in the forest floor, and was photographed by the researchers crouching between branches. 

It's possible that the ultra-bright appearance acts as a warning for predators that they carry poison, but it also might have evolved so potential mates can find each other in dim light. 

Or, their appearance could simply be used as an effective camouflage, the study authors suggest.

The researchers had travelled just south of the Mantiqueira mountain range several times to collect pumpkin toadlets.  

They team collected 276 pumpkin toadlet specimens (helped in part by the use of fluorescent light), which they took back to their lab for analysis, including DNA tests. 

The analysis revealed the some of the frogs had distinct new characteristics, including faded dark spots on the skull and a rounded snout that were unlike the other species they collected.

This heralded the discovery of a new species, which they named B. rotenbergae after a Brazilian conservationist called Elise Laura K. Rotenberg.

Rotenberg is a founder of the Brazilian NGO Projeto Danis, a project that works to conserve forest where the toadlets live.