A New Hybrid between Brazilian Tree Ferns (Cyatheaceae)

After studying a mixed population of Cyathea atrovirens and C. corcovadensis s. str., we describe a new local, occasional hybrid between those two species: C. ×insulae-melliferae, hybr. nov, from an island in southern Brazil. The three hybrid individuals were intermediate in morphology between the two parents, most noticeably in pinnule shape and cutting. The hybrid individuals are at least 10 years old; we first saw them in 2016. They have trunks about 1 m tall and ca. 25 cm diam. In the rbcL chloroplast gene, C. atrovirens differs only two nucleotides from C. corcovadensis. We were able to sequence two hybrid specimens, one of which has the rbcL sequence identical to C. atrovirens, and the other identical to C. corcovadensis. This suggests that the two hybrid individuals had different maternal parents.