Filling knowledge gaps about the Data Deficient species Zachaenus carvalhoi Izecksohn, 1982 (Anura: Cycloramphidae): an endemic frog from the Atlantic Forest of southeastern Brazil

Zachaenus carvalhoi is an endemic frog from the Atlantic Forest of southeastern Brazil. It is considered a rare species, being currently classified as Data Deficient by the IUCN due to the shortage of information about its natural history and ecological requirements. In the present study, we aim to fill gaps into the current knowledge of this species by: updating its altitudinal distribution range; describing its release call; providing new natural history data; and describing its karyotype. During fieldwork in the municipality of Cataguases, Minas Gerais State, we recorded individuals Z. carvalhoi in three small forest fragments, one of them at only 230 m a.s.l., which now represents the lowest known altitudinal record for this species. In all occasions, we only recorded this frog in vocalization activity during rainy days, suggesting an opportunistic breeding strategy. Moreover, the karyotype of Z. carvalhoi (2n=26) is similar to other species of the family Cycloramphidade, but it differs remarkably in morphology and fundamental number. About its release call, it diverged from the advertisement call in the spectral structure, which contradicts the hypothesis that both should be similar in this parameter. In conclusion, Z . carvalhoi seems to be an explosive breeder occurring along a wide altitudinal range (low- and highland Atlantic Forest), thus physical barriers such mountain chains may not be a constraint to the dispersal of it. Furthermore, this species represents a promising subject for investigations over both bioacoustics and cytogenetic studies.