One more step into the resolution of Panicum (Poaceae) polyphyly: Drakkaria, a new segregate genus from neotropical Seasonally Dry Tropical Forests

Abstract

Panicum was once one of the largest grass genera with >450 species associated to >4000 names. The revelation of its polyphyletic nature emerged with the use of molecular data in phylogenetic studies. Consequently, most of its species have been transferred to other genera. A notable case occurred with Panicum (subg. Phanopyrum) sect. Stolonifera, whose species were recovered in tribe Paspaleae, distantly related to Panicum s.s. (P. subg. Panicum), placed in tribe Paniceae. Most species from the section were transferred to Ocellochloa, leaving only one enigmatic species, P. venezuelae, remaining as incertae sedis. In this study, we endeavoured to clarify the phylogenetic placement of P. venezuelae by expanding the taxon sampling and increasing the number of molecular markers. The nuclear External Transcribed Spacer marker was used for the first time in a comprehensive analysis of Paspalinae genera. Additionally, we reviewed the literature and herbarium records to provide a comprehensive update on the morphology and distribution of the species, and a conservation assessment. Our findings confirm that Panicum venezuelae belongs to the tribe Paspaleae, which is here transferred to a new genus, Drakkaria. However, identifying its closest relative remains an open question within Paspaleae. The new genus is considered here endemic to the diverse and threatened Neotropical Seasonally Dry Tropical Forests.