Preliminary study on phylogenetic position and delimitation of the ciliate arthrodontous genera of the moss family Mniaceae

The history of the generic and sectional concepts in the traditional moss family Mniaceae is summarised. The division of the Mniaceae into nine genera has been generally accepted. A phylogenetic analysis, based on 35 Mniaceae samples as ingroup and one Leptostomataceae and three Bryaceae samples as outgroups was completed. A total of 113 new sequences were obtained and 4139 aligned characters were included in the combined dataset. Bayesian inferences based on the combined data set showed five well supported clades, which, as a whole, form the monophyletic family Mniaceae. The number of genera in the traditional Mniaceae is 9 and the number of species is 74. All the genera appear monophyletic except Plagiomnium; accepting Orthomnion at the generic level makes Plagiomnium paraphyletic. The principle that only monophyletic taxa are allowed and may be named necessitates the uniting of Plagiomnium and Orthomnion. The necessary combinations are made. The taxonomy of the genera and sections is discussed. Rhizomnium section Macromnium T.J.Kop. & Y.Sun, sect. nov. is described and the new combination Rhizomnium chlorophyllosum (Kindb.) T.J.Kop. is made. The controversy of paraphyly – monophyly in accepting and naming taxa is discussed and Plagiomnium versus Orthomnion given as an example. All the present genera and species seem to have diverged in the area of the Laurasian supercontinent and the speciation of most genera took place in the temperate forested areas of western and eastern North America, Europe and south-eastern Asia.