Phylogenetic analyses reveal high levels of polyphyly amongpleurocarpous lineages as well as novel clades

摘要

Phylogenetic analyses of the Hypnales usually show the same picture of poorlyresolved trees with a large number of polyphyletic taxa and low support for the fewreconstructed clades. One odd clade, however, consisting of three genera that are currently treated either within the Leskeaceae (Miyabea) or Neckeraceae (Homaliadelphus andBissetia), was retrieved in a previously published phylogeny based on chloroplast rbcL. Inorder to elucidate the reliability of the observed Homaliadelphus - Miyabea - Bissetia -clade'(HMB-clade) and to reveal its phylogenetic relationships a molecular study based on arepresentative set of hypnalean taxa was performed. Sequence data from all three genomes,namely the ITS1 and 2 (nuclear), the trnS-rps4-trnT-trnL-trnF cluster (plastid), the nad5intron (mitochondrial), were analyzed. Although the phylogenetic reconstruction of thecombined data set was not fully resolved regarding the backbone it clearly indicated thepolyphyletic nature of various hypnalean families, such as the Leskeaceae, Hypnaceae,Hylocomiaceae, Neckeraceae, Leptodontaceae and Anomodontaceae with respect to theincluded taxa. In addition the results favor the inclusion of the Leptodontaceae andThamnobryaceae in the Neckeraceae. The maximally supported HMB-clade consisting ofthe three genera Homaliadelphus (2-3 species), Miyabea (3 species) and Bissetia (1 species)is resolved sister to a so far unnamed clade comprising Taxiphyllum aomoriense,Glossadelphus ogatae and Leptopterigynandrum. The well-resolved and supported HMB-clade, here formally described as the Miyabeaceae, fam. nov. is additionally supported bymorphological characters such as strongly incrassate, porose leaf cells, a relatively weak anddiffuse costa and the presence of dwarf males. The latter are absent in the Neckeraceae andthe Leskeaceae. It is essentially an East Asian family, with one species occurring in NorthAmerica.