related red pumpkin toadlet are unable to hear the frequency of their own advertising calls, as their ears are underdeveloped. Instead their communication appears to rely on certain movements like the vocal sac that inflates when calling, mouth gaping and waving of their arms. It is speculated that their calling is a vestigiality from the ancestral form of the genus, whereas their reduced hearing ability (they do have some hearing ability in frequencies outside their call) is a novel change in these species. Sounds make them more vulnerable to predators, but there has likely been little direct evolutionary pressure to lose it because of their toxicity. See also Polka-dot tree frog (Hypsiboas punctatus) — the first frog discovered to be fluorescent, in 2017 References Amphibians of Brazil Brachycephalus Endemic fauna of Brazil Taxonomy articles created by Polbot Amphibians described in 1824