Phylogeny of haplolepideous mosses - Challenges and perspectives

The haplolepideous mosses (Dicranidae) form the second largest group of mosses and are morphologically and ecologically highly diverse. This review summarizes the current state and addresses the most urgent remaining problems in unravelling systematic relationships in the haplolepideous mosses. The main results of early molecular phylogenetic reconstructions based on few chloroplast markers are compared with recent approaches based on markers from different genomes as well as with a new phylogeny based on a novel combination of non-coding plastid markers (rps4-trnF region and atpB-rbcL spacer). According to the available molecular data, three major groups are provisionally distinguished within Dicranidae. The first group comprises morphologically diverse species from different families (Bryoxiphiaceae, Catoscopiaceae, Distichiaceae, Ditrichaceae p.p., Drummondiaceae, Pottiaceae p.p., Rhabdoweisiaceae p.p., and Scouleriaceae p.p.), which form grades branching off first in the phylogenetic reconstructions. The second group, which appears as a grade or unsupported clade, includes Grimmiales, Leucobryaceae, Archidiaceae, Eustichiaceae, and Saelania glaucescens (Ditrichaceae). The third group comprises the largest portion of the haplolepideous mosses, namely most families of Dicranales as well as the most speciose Pottiales; the respective clades receive significant statistical support in part of the analyses. The position of Amphidium in between the second and third group remains ambiguous. It is concluded that further phylogenetic analyses based on new combinations of markers are necessary at different taxonomic levels, especially to resolve the backbone of the Dicranidae phylogeny, but also to tackle large and taxonomically complex genera that are severely understudied. Implications of the molecular phylogenetic reconstructions for morphological character evolution are exemplarily discussed for the different types of haplolepideous peristomes. Furthermore, genetic and genomic research using haplolepideous taxa is briefly reviewed. © British Bryological Society 2012.