Circumscription and Phylogenetic Position of Rhizogoniaceae

Pyrrhobryum was split into two sections by Manuel (1980), who recognized P. Section Bifariella and P. Section Pyrrhobryum. This view is partially supported by my results. I sampled two taxa, P. bifariella and P. mnioides, from Section Bifariella, and three taxa, P. latifolium, P. paramattense and P. spiniforme, from Section Pyrrhobryum. The taxa of Section Bifariella are in a clade (A) that includes Aulacomnium, Hymenodontopsis and Mesochaete, while the taxa of Section Pyrrhobryum sampled are in a clade (C) that includes Calomnion and Cryptopodium. The evidence from this study does not support the inclusion of these sections in a single genus, but supports the circumscription of the sections. Bell and Newton (2004) also found that the sections of Pyrrhobryum are non-monophyletic, and in their trees, the positions of the sections correspond to clades A and C. An additional seven species of Pyrrhobryum are known (Crosby et al., 2004) that were not sampled in this study, and these should be evaluated before taxonomic decisions are made. 

Several authors (Brotherus, 1924-1925 Vitt, 1984 Buck and Goffinet, 2000 and others, summarized in Shaw, 1985 and Stone, 1986) have proposed classifications in which Mittenia is included within diplolepidous-altemate mosses. Vitt (1984) considered Rhizogoniaceae to be the sister group to Mittenia and Schistostega D. Mohr, whereas Buck and Goffinet (2000) include 

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