Abstract
A taxonomic treatment, phylogeny based on analysis of six DNA sequence markers (ITS, ndhA intron, rpl32-trnL, rps3, rps16 intron and rps16-trnK) and classification of Muhlenbergia for Peru is given. Seventeen species and one presumed hybrid are recognised. Muhlenbergiaromaschenkoi sp. nov. is newly described from the Río Huallaga Valley, northeast of Huánuco. The type of Podosemumangustatum [≡ Muhlenbergiaangustata] clearly aligns with what we had been referring to as the hybrid between this species and M.rigida. Therefore, we adopt the next available heterotypic name, Muhlenbergiacoerulea, for what we had been calling M.angustata and change the hybrid designation to M.coerulea × M.rigida. Lectotypes are designated for Epicampescoerulea Griseb., Muhlenbergiaaffinis Trin., Muhlenbergiaberlandieri Trin., Muhlenbergiabeyrichiana Kunth, Muhlenbergiaelegansvar.atroviolacea Kuntze, Muhlenbergiaelegansvar.subviridis Kuntze and Muhlenbergiaphragmitoides Griseb.