XVI International Botanical Congess

Bahianthus R.King & H.Rob. and Morithamnus R.King & H.Rob. are two endemic genera from Bahia (Brazil), belonging to the subtribe Gyptidinae (Eupatorieae, Asteraceae). King & Rob. consider that these two genera are closely related. Bahianthus viscosus and Morithamnus crassus, the first species described in these genera show very pronunced morphological differences. However, the morphological characters of M. ganophyllus are ambiguous, and its inclusion in the genus Morithamnus was called into question by the authors of the proposal themselves. We present a taxonomic study of the species of these two genera and an analysis of their phylogenetic relationships. The results of this study argue for the creation of a new genus, which we name Piatanthus, to include the species Morithamnus ganophyllus.