Parahellenia, a new genus segregated from Hellenia (Costaceae) based on phylogenetic and morphological evidence

Previous studies recognized three major lineages of the family Costaceae: a South American Glade, an Asian Glade and a Costus Glade. However, the genus Hellenia within the Asian Glade has been shown to be non-monophyletic and its morphology has not been studied carefully. Therefore, the complete plastid genomes of Hellenia species were obtained and the monophyly of Hellenia was tested through four different datasets in this study. Plastid phylogenomic analyses of Costaceae revealed that Hellenia is strongly supported as paraphyletic. Two major clades are recovered, namely the Hellenia s.s. subclade and the Parahellenia subclade. Phylogenetic analyses based on an enlarged taxon sampling of the Asian Glade using a two chloroplast markers dataset (trnK intron and trnL-F spacer) confirmed the paraphyly of Hellenia. Meanwhile, morphological analyses suggested that members of the Parahellenia subclade differ from the remaining Hellenia species in many characters including inflorescences, bracts, stigma, axillary buds, floral tubes and labellum. According to the present molecular and morphological evidence, the latter subclade is recognized as a new genus, Parahellenia. Two new species are described, four new combinations are made, and identification keys are also provided. Copyright (C) 2022 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

Previous studies have revealed that the genus Hellenia within the family Costaceae is non-monophyletic. This study further confirms the paraphyly of Hellenia through plastid phylogenomic analyses and morphological analyses. A new genus, Parahellenia, is recognized based on the molecular and morphological evidence.