Phylogenetic relationships among the diplolepideous-alternate mosses (Bryidae) inferred from nuclear and chloroplast DNA sequences

The diplolepideous-alternate peristome, when most highly developed, has end ostome segments attached to a basal membrane and positioned alternate to th e outer exostome teeth, with cilia often present between the segments. This peristome type defines the Bryidae (sensu Vitt ct al. 1998), which include s four orders: the Bryales, Leucodontales, Hypnales, ann Hookeriales, of wh ich the latter three are mainly pleurocarpous in their growth form. Chlorop last (rbcL, rps4, and trnL-trnF) and nuclear (18S rRNA) gene sequences have been analyzed using the parsimony optimality criterion to elucidate relati onships among the Bryidae. The analyses strongly support the paraphyly of t he Bryidae, with the Splachnidae, and possibly the Orthotrichidae, having a risen from ancestors within the Bryidae. The Leucodontales, Hypnales, and H ookeriales form a monophyletic group, as do the pleurocarpous members of th e Bryidae. However, the two pleurocarpous clades are riot resolved as siste r groups, although their non-monophyly is riot supported by the bootstrap. The phylogenetic hypothesis provides a context irt which to infer evolution ary transitions in sol,le key morphological characters relating to the peri stome nod the transition from the acrocarpous to pleurocarpous growth forms .