Taxonomic Re-evaluation of Actinocephalus (Eriocaulaceae) in Light of New Morphological and Molecular Evidence

Abstract

Abstract— A recent phylogenetic tree for the large paraphyletic genus Paepalanthus showed that the genus Actinocephalus is also paraphyletic with two species of Paepalanthus nested within it: Paepalanthus macrocephalus and Paepalanthus camptophyllus. These species have the diagnostic morphological traits of Actinocephalus, but they are too small to be seen in Paepalanthus macrocephalus and difficult to interpret in Paepalanthus camptophyllus, which has resulted in them being overlooked until now. Furthermore, Paepalanthus macrocephalus has a challenging circumscription, with several putative synonyms whose nomenclatural confusion has persisted for decades. Here we analyzed the morphology of Paepalanthus camptophyllus and Paepalanthus macrocephalus to confirm their relationship with other species of Actinocephalus as shown in the phylogeny and to investigate the diagnostic features that distinguish these species in Actinocephalus. The opportunity was also taken to evaluate putative synonyms of Paepalanthus macrocephalus and Paepalanthus camptophyllus, and to include the remaining variety of A. phaeocephalus (Paepalanthus phaeocephalus var. foliosus) in Actinocephalus, which was lacking in the revision of the genus. Four new combinations and eight lectotypes are provided, as well as six new synonyms. We also provide comments on diagnostic characteristics, distribution, and notes on Actinocephalus.