Systematic studies in Paniceae (Poaceae):: Homopholis and Whalleya gen. et sp nov.

The taxonomy of Homopholis C. E. Hubb. is revised, and a new genus Whalleya K. E. Wills & J. J. Bruhl is described. Relationships among the known species of Homopholis (H. belsonii C. E. Hubb., H. proluta F. Muell., and a putative species, H. sp. nov.), and the relationships between Homopholis and other genera within the Paniceae were investigated. Morphological and anatomical data for Homopholis and selected species of Digitaria and Panicum were analysed phenetically and cladistically. The value and contribution of characters to the findings were assessed. In the phenetic analyses, three distinct clusters of species were formed. The first cluster included Digitaria coenicola (F. Muell.) Hughes, D. divaricatissima (R. Br.) Hughes and D. papposa (R. Br.) P. Beauv.; the second, Panicum effusum R. Br., P. queenslandicum Domin var. queenslandicum and P. simile Domin; and the third, H. sp. nov., H. proluta, H. belsonii and P. subxerophilum Domin. Specimens of H. belsonii noticeably separated from the other three species. For the cladistic analyses, species of Entolasia and Thyridolepis were used as outgroup taxa. One most parsimonious tree was produced. Homopholis belsonii was well supported as the most basal member of the ingroup. The three species of Digitaria formed a well-supported clade. Panicum effusum, P. queenslandicum var. queenslandicum and P. simile formed a well-supported clade, and were the sister group to Entolasia marginata (R. Br.) Hughes and E. stricta (R. Br.) Hughes. Panicum subxerophilum was in a clade (= Whalleya) with H. sp. nov. and H. proluta, with P. subxerophilum and H. proluta as sister species.