Circumscription, classification, and taxonomy of Amblystegiaceae (Bryopsida) inferred from nuclear and chloroplast DNA sequence data and morphology

Results from a previous broad-scale analysis employing trnL-trnF sequence data for 168 Hypnalean and 11 Hookerialean taxa, and an analysis employing two chloroplast regions, trnL-trnF and atpB-rbcL, one nuclear region, the internal transcribed spacers of 18S-26S rDNA, plus 68 morphological characters for a reduced data set of 54 Hypnalean taxa, were used to circumscribe Amblystegiaceae. The analyses provided two well-supported main clades including taxa traditionally included in Amblystegiaceae s.l. and recognized as Amblystegiaceae s.str. [Anacamptodon, Amblystegium, Campyliadelphus, Campylium, Cratoneuron, Cratoneuropsis, Drepanocladus s.str., Gradsteinia, Hygrohypnum s.str. (including the type species, H. luridum, but excluding a number of other species previously accommodated in the genus), Hypnobartlettia, Leptodictyum, Palustriella, Pseudo-calliergon, and Serpoleskea] and Calliergonaceae stat. nov. (Calliergon, Hamatocaulis, Loeskypnum, Straminergon, and Warnstorfia). Scorpidium and "Hygrohypnum" ochraceum were closely related to Calliergonaceae but were not included in the family because of the lack of support. All these genera but Anacamptodon have previously been included in Amblystegiaceae s.l. The sporophytic features of Anacamptodon, which contrast with those of all the other members of Amblystegiaceae, are interpreted as adaptations to an epiphytic habitat and suggest, together with other recent taxonomic works in Hookeriales, that characters related to sporophytic specializations are among the most homoplastic. Several other taxa (Calliergonella, Campylophyllum, Conardia, Donrichardsia, "Hygrohypnum" smithii, Platydictya, Sanionia), previously included in Amblystegiaceae s.l., appeared more closely related to other Hypnalean families. Recircumscribed Amblystegiaceae, and several clades within the family, have no identifiable morphological synapomorphies. A new system of classification for recircumscribed Amblystegiaceae, including morphological delimitation of presented clades based on maximum likelihood reconstruction of ancestral character states, is proposed and appropriate nomenclatural changes made