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

Abstract

The taxonomy ofHomopholis C.E.Hubb. is revised, and anew genus Whalleya K.E.Wills & J.J.Bruhl isdescribed. Relationships among the known species ofHomopholis (H. belsonii C.E.Hubb.,H. proluta F.Muell., and a putative species,H. sp. nov.), and the relationships betweenHomopholis and other genera within the Paniceae were investigated. Morphological and anatomical data forHomopholis and selected species ofDigitaria and Panicum were analysed phenetically and cladistically. The value and contribution ofcharacters to the findings were assessed. In the phenetic analyses, threedistinct clusters of species were formed. The first cluster includedDigitaria coenicola (F.Muell.) Hughes,D. divaricatissima (R.Br.) Hughes andD. papposa (R.Br.) P.Beauv.; the second,Panicum effusum R.Br.,P. queenslandicum Domin var.queenslandicum and P. simileDomin; and the third, H. sp. nov.,H. proluta, H. belsonii andP. subxerophilum Domin. Specimens ofH. belsonii noticeably separated from the other threespecies. For the cladistic analyses, species ofEntolasia and Thyridolepis were used as outgroup taxa. One most parsimonious tree was produced.Homopholis belsonii was well supported as the most basalmember of the ingroup. The three species ofDigitariaformed a well-supported clade.Panicum effusum, P. queenslandicumvar. queenslandicum and P. simileformed a well-supported clade, and were the sister group toEntolasia marginata (R.Br.) Hughes andE. stricta (R.Br.) Hughes.Panicum subxerophilum was in a clade (=Whalleya) with H. sp. nov. andH. proluta, with P. subxerophilumand H. proluta as sister species.