Distribution expansion of Petrocerus catiena (Hewitson, 875) (Lepidoptera: Riodinidae) and description of the previously unknown female

Petrocerus catiena is a rarely observed Riodinidae butterfly, known from a few specimens from two locations in Serra do Mar (Atlantic Forest) in the Brazilian state of Rio de Janeiro. This species was listed as “Endangered” in the Brazilian Red List due to its small area of occupation and isolated populations under strong anthropogenic pressure. Based on scientific collections and citizen science data, the present study provides information about new geographic records of P. catiena and its perspectives on conservation. A total of 19 specimens of P. catiena were found in six public / private collections, as well as six photograph records of live specimens from citizen science reports. A recent photograph from a locality in the state of Espírito Santo (southeastern Brazil) resulted in an increase in both the extent of occurrence and the area of occupation estimates of P. catiena, implying a possible change in its conservation status. Besides providing new geographical information for a little-known species, the present study also highlights the importance of citizen science in contributing to the knowledge of threatened species and their conservation assessments.