Molecular evolution and diversification of the moss family Daltoniaceae (Hookeriales, Bryophyta) with emphasis on the unravelling of the phylogeny of Distichophyllum and its allies BOON-CHUAN HO 1,2 * ,† , LISA POKORNY 2 †, BENITO C. TAN 3 , JAN-PETER FRAHM 1 , A. JONATHAN SHAW 2 and DIETMAR QUANDT 1 1 Nees-Institut für Biodiversität der Pflanzen, Rheinische Friedrich-Wilhelms-Universität Bonn, Meckenheimer Allee 170, D-53115 Bonn, Germany 2 Department of Biology, Duke University, Durham, NC 27708, USA 3 Department of Biological Sciences, National University of Singapore, Singapore 119260 Received 19 January 2012; revised 4 May 2012; accepted for publication 31 May 2012 Phylogenetic relationships in Daltoniaceae (~200 species in 14 genera) are inferred from nucleotide sequences from five genes, representing all genomic compartments, using parsimony, likelihood and Bayesian methods. Alternative classifications for Daltoniaceae have favoured traits from either sporophytes or gametophytes; phylogenetic transitions in gametophytic leaf limbidia and sporophytic exostome ornamentation were evaluated using ancestral state reconstruction to assess the levels of conflict between these generations. Elimbate leaves and the cross-striate exostome are reconstructed as plesiomorphic states. Limbate leaves and papillose exostomes evolved at least two and six times, respectively, without reversals. The evolution of leaf limbidia is relatively conserved, but exostome ornamentation is highly homoplasious, indicating that superficial similarity in peristomes gives unreliable approximations of phylogenetic relatedness. Our phylogenetic analyses show that Achrophyllum and Calyptrocha- eta are reciprocally monophyletic. Within core Daltoniaceae, relationships among taxa with elimbate leaves are generally well understood. However, taxa with limbate leaves form a monophyletic group, but resolved subclades correspond to biogeographical entities, rather than to traditional concepts of genera. Daltonia (~21 species), Distichophyllum (~100 species) and Leskeodon (~20 species) are polyphyletic. Seven nomenclatural changes are proposed here. As the current taxonomy of Daltoniaceae lacks phylogenetic consistency, critical generic revisions are needed. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ••, ••–••. ADDITIONAL KEYWORDS: Achrophyllum – ancestral states – Calyptrochaeta – Daltonia – exostome ornamentation – Leskeodon – limbidium. INTRODUCTION Insights into phylogenetic relationships enable a better understanding of morphology and morphologi- cal evolution. Because all land plants are characterized by an alternation of sporophytic and gametophytic generations, a phylogenetic context can help to clarify how evolutionary change has occurred in the two generations, in concert and independently. In mosses (Bryophyta), conflicting classifications with an empha- sis on either sporophytes or gametophytes are common because both generations are relatively well developed and provide characters that may be useful for phylo- genetic inference and classification. Daltoniaceae (Hookeriales: Bryophyta) exemplifies the systematic challenge that may result from focusing taxonomic inferences on traits from just one genera- tion (i.e. gametophytes vs. sporophytes). Daltoniaceae comprises a prominent group of tropical and south- temperate mosses that prefer humid forest habitats. *Corresponding author. E-mail: calyptrochaeta@yahoo.com †These authors contributed equally in partial fulfilment of the requirements for their respective doctoral degrees. Botanical Journal of the Linnean Society, 2012, ••, ••–••. With 3 figures © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ••, ••–•• 1