A Generic Classification of the Danthonioideae (Poaceae)¹

Abstract

We present a new generic classification of the largely Southern Hemisphere grass subfamily Danthonioideae. This classification is based on an almost completely sampled and well-resolved molecular phylogeny and on a complete morphological data set. We have attempted to delimit monophyletic genera (complicated by the presence of apparent intergeneric hybridization), which are diagnosable, as well as morphologically and ecogeographically coherent. We recognize 17 genera, including five new genera (Austroderia N. P. Barker & H. P. Linder, Capeochloa H. P. Linder & N. P. Barker, Chimaerochloa H. P. Linder, Geochloa H. P. Linder & N. P. Barker, and Tenaxia N. P. Barker & H. P. Linder), and two sections newly designated for Pentameris P. Beauv. (section Dracomontanum H. P. Linder & Galley and section Pentaschistis (Nees) H. P. Linder & Galley). Of the remaining 12 genera, the delimitations of seven are changed: Merxmuellera Conert is much reduced by the segregation of Geochloa, Capeochloa, and Tenaxia; Pentameris is expanded to include Prionanthium Desv. and Pentaschistis (Nees) Spach; Cortaderia Stapf is expanded by the inclusion of Lamprothyrsus Pilg., but reduced by the segregation of its New Zealand species into the new genus Austroderia; a large Rytidosperma Steud. is assembled out of Joycea H. P. Linder, Austrodanthonia H. P. Linder, Notodanthonia Zotov, Erythranthera Zotov, Pyrrhanthera Zotov, and Monostachya Merr.; and the species previously assigned to Karroochloa Conert & Türpe, Schismus P. Beauv., Urochlaena Nees, and Tribolium Desv. have been reassigned to only two genera. Finally, the Himalayan species of Danthonia DC. are transferred to Tenaxia and the remaining African species of Danthonia to Merxmuellera. The 281 species that we recognize in the subfamily are listed under their new genera, which are arranged in the phylogenetic sequence evident from the molecular phylogeny. The 100 necessary new combinations include: Merxmuellera grandiflora (Hochst. ex A. Rich.) H. P. Linder, Geochloa decora (Nees) N. P. Barker & H. P. Linder, G. lupulina (L. f.) N. P. Barker & H. P. Linder, G. rufa (Nees) N. P. Barker & H. P. Linder, Capeochloa arundinacea (P. J. Bergius) N. P. Barker & H. P. Linder, C. cincta (Nees) N. P. Barker & H. P. Linder, C. cincta subsp. sericea (N. P. Barker) N. P. Barker & H. P. Linder, C. setacea (N. P. Barker) N. P. Barker & H. P. Linder, Pentameris praecox (H. P. Linder) Galley & H. P. Linder, P. tysonii (Stapf) Galley & H. P. Linder, P. acinosa (Stapf) Galley & H. P. Linder, P. airoides Nees subsp. jugorum (Stapf) Galley & H. P. Linder, P. alticola (H. P. Linder) Galley & H. P. Linder, P. ampla (Nees) Galley & H. P. Linder, P. andringitrensis (A. Camus) Galley & H. P. Linder, P. argentea (Stapf) Galley & H. P. Linder, P. aristidoides (Thunb.) Galley & H. P. Linder, P. aristifolia (Schweick.) Galley & H. P. Linder, P. aspera (Thunb.) Galley & H. P. Linder, P. aurea (Steud.) Galley & H. P. Linder, P. aurea subsp. pilosogluma (McClean) Galley & H. P. Linder, P. bachmannii (McClean) Galley & H. P. Linder, P. barbata (Nees) Steud. subsp. orientalis (H. P. Linder) Galley & H. P. Linder, P. basutorum (Stapf) Galley & H. P. Linder, P. borussica (K. Schum.) Galley & H. P. Linder, P. calcicola (H. P. Linder) Galley & H. P. Linder, P. calcicola var. hirsuta (H. P. Linder) Galley & H. P. Linder, P. capensis (Nees) Galley & H. P. Linder, P. capillaris (Thunb.) Galley & H. P. Linder, P. caulescens (H. P. Linder) Galley & H. P. Linder, P. chippindalliae (H. P. Linder) Galley & H. P. Linder, P. chrysurus (K. Schum.) Galley & H. P. Linder, P. clavata (Galley) Galley & H. P. Linder, P. colorata (Steud.) Galley & H. P. Linder, P. dentata (L. f.) Galley & H. P. Linder, P. dolichochaeta (S. M. Phillips) Galley & H. P. Linder, P. ecklonii (Nees) Galley & H. P. Linder, P. exserta (H. P. Linder) Galley & H. P. Linder, P. galpinii (Stapf) Galley & H. P. Linder, P. holciformis (Nees) Galley & H. P. Linder, P. horrida (Galley) G