Researchers have identified a new species of tiny frog in the mountainous forests of southeastern Brazil. The discovery was made during two field expeditions in December 2021 and March 2022, where scientists searched through leaf litter in Estação Ecológica de Bananal, part of the Serra da Bocaina Mountain range.
“We actively searched the area with careful removal and analysis of the leaf litter at the site, dedicating seven hours for day search and two hours for night search, totalizing 40 hours of effort/person,” researchers said.
The team found six frogs that measured less than a centimeter long. These amphibians belong to a group known as flea-toads or “pumpkin toadlets.” Their bodies are slender with heads as wide as they are long. The frogs display mostly brown coloring with some golden spots on their backs and a golden stripe running from their snout to their sides. Their arms and legs feature dark brown stripes.
All specimens were discovered sheltering under leaves or fallen trees. Researchers observed different defensive behaviors among them: “The specimens displayed different defensive behaviors upon our approach: motionless, crouching down posture, or fleeing by jumping away,” according to the study. “… Being motionless or in a crouching posture, in addition to its cryptic coloration, provides individuals an advantage against visually oriented predators. Fleeing by jumping, besides avoiding subjugation, could be especially successful for the flea-toads, which could jump several times its body length, falling in the matching background leaf litter far from the predator.”
The frogs were mostly active during daylight hours and more likely to emerge on moist days due to their vulnerability to drying out because of their small size. “For this reason, the leaf litter environment is important, because it provides not only shelter but also the moisture that protects the frogs from desiccation even in the driest or coldest conditions,” according to the study.
L. Felipe Toledo, one of the authors of the study published September 9 in Zootaxa, noted that little is known about this species beyond what has been documented so far: “It is worth noting that this species is micro-endemic — only known to a single spot in the Atlantic rainforest and we still don’t know much about the species, not even its vocalization was recorded,” Toledo told McClatchy News via email. “But, we have some data on diet and anatomy — in the paper — which is rare for these tiny species.”
Flea-toads typically inhabit elevations above 6,500 feet and are recognized for either cryptic or conspicuous coloration patterns. While members of this genus are spread across a broad geographic area within Brazil’s Atlantic rainforest region (https://en.wikipedia.org/wiki/Atlantic_Forest), most individual species occupy very limited ranges.
The newly described frog has been named Brachycephalus nanicus; “Brachycephalus” refers to flea-toads generally while “nanicus” derives from Latin meaning “those with reduced size.”
Bananal is located within São Paulo state.
The research team involved scientists from multiple institutions including L. Felipe Toledo and others.
