The unique traits of the subgenus Unicus within Chiasmocleis Méhely, 1094 (Anura: Microhylidae).

Chiasmocleis is the most speciose genus of Neotropical microhylids. The genus consists of three monophyletic clades that were recently recognized as subgenera. Within Chiasmocleis, the subgenus Unicus has a basal position in the phylogeny and contains a single species that occurs in the North Atlantic Forest of Brazil, isolated from the ranges of other Chiasmocleis. However, the subgenus Unicus lacked a formal description and consequently so far was a nomen nudum. Herein, we provide a diagnosis (i.e., morphological and molecular apomorphies) of the subgenus Unicus de Sá, Tonini, van Huss, Long, Cuddy, Forlani, Peloso, Zaher and Haddad, 2019b; for convenience, the name has also been registered in ZooBank.