Scientists have described a new species of the frog genus Brachycephalus from the forests of the Brazilian state of São Paulo.
Brachycephalus is a genus of miniaturized frogs that live in the forest leaf litter and are most active during daylight.
Commonly known as pumpkin toadlets, these frogs are endemic to the Brazilian Atlantic Forest, eastern Brazil, and are spread along almost 1,700 km, from Santa Catarina to southern Bahia states.
Regardless of genus distribution, most species occur in restricted lowlands or mountains areas, where some representatives seem to occupy less than 100 ha of area.
The newfound species, named Brachycephalus rotenbergae, inhabits the south Mantiqueira mountain range and the semidecidual forests in the municipalities of Mogi das Cruzes, Campinas and Jundiaí, in the Brazilian state of São Paulo.
“The description of Brachycephalus rotenbergae is based on an integrative approach, coupling external morphology, coloration, osteology, vocalization, and genetic data,” said lead author Dr. Ivan Nunes from the Universidade Estadual Paulista and colleagues.
Brachycephalus rotenbergae has a bright orange overall coloration, a robust body, a wide head, and a short snout.
Color is the same among adults, but different between adults and juveniles: the juvenile specimens are slightly darker, as reported for other Brachycephalus species.
Adult males are between 1.35 and 1.6 cm long and females are between 1.6 and 1.8 cm.
“Brachycephalus rotenbergae’s colors may work as a camouflage in their microhabitat, since there are great amounts of tiny yellow and orange leaves, mushrooms and seeds on the ground, especially during the active season,” the researchers said.
“Together, these elements make the specimens’ bright colors not as conspicuous as they may seem.”
“During our field surveys, it was quite common to mistake a specimen for other yellow/orange small things on the landscape.”
“Like other Brachycephalus species, Brachycephalus rotenbergae presented fluorescence when backlighted by a UV flashlight,” they added.
The new species is predominantly active by day on the forest floor and, occasionally, on low perches up to 50 cm.
Males usually hold a territory for advertisements by acoustical and visual signals.
“We detected gaping defensive behavior in three specimens that were manipulated, and we saw them opening their mouths widely,” the scientists said.
“The gaping and the flee away strategies were the two defensive displays that Brachycephalus rotenbergae presented during our study.”
The discovery of Brachycephalus rotenbergae is reported in a paper in the journal PLoS ONE.
I. Nunes et al. 2021. Hidden by the name: A new fluorescent pumpkin toadlet from the Brachycephalus ephippium group (Anura: Brachycephalidae). PLoS ONE 16 (4): e0244812; doi: 10.1371/journal.pone.0244812