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Abstract

We used information on six gene regions - three nuclear protein-coding markers (Mcm7, GAPDH and Tsr1), two nuclear ribosomal markers (ITS rDNA and IGS rDNA), and a partial mitochondrial small subunit (mtSSU rDNA) - to examine infrageneric relationships in the genus Bryoria (Parmeliaceae, Lecanoromycetes) and to assess species delimitation in Bryoria bicolor/B. tenuis group in section Divaricatae. Our phylogenetic analyses based on the combined data set of six gene loci support the monophyly of sections Americanae, Divaricatae and Implexae, while section Bryoria is polyphyletic and groups in two clades. Species from Bryoria clade 1 are placed in an emended section Americanae. Our study reveals that section Divaricatae is young (c. 5 My) and undergoing diversification especially in South East Asia and western North America. Separate phylogenetic analyses of section Divaricatae using ITS produced a topology congruent with the current species concept. However, the remaining gene regions produced poorly resolved phylogenetic trees and the different species delmitation methods also gnerated highly inconsistent resluts, congruent with other studies that highlight the difficulty of species delmitation in groups with recent and rapid radiation. Based on our results we describe the new species B. ahtiana sp. nov., characterized by its bicolorous, caespitose, widely divergent thallus, conspicuously thickening main stems, well developed secondary branches, and rather sparse third-order branchlets. Another new lineage, here referred to as B. tenuis s. lat., is restricted to western North America and may represent a new species recently diverged from B. tenuis s. str., though further work is needed.

A total of 71 Bryoria specimens from North America, Europe and Asia were used in the molecular phylogenies. Six markers were used: ITS rDNA regions, IGS rDNA, partial mtSSU rDNA gene, partial Mcm7 gene, partial GAPDH gene and partial Tsr1 gene. Seven data sets were prepared: 1) six-locus data set to examine infrageneric classification. The data set included 64 ingroup specimens and Usnea dasopoga was used as an outgroup taxon; 2-7) separate ITS (42 specimens), IGS (30 specimens), mtSSU (30 specimens), GAPDH (27 specimens), Mcm7 (31 specimens) and Tsr1 (15 specmiens) data sets to examine phylogeny and species delimitation within the Bryoria bicolor/B. tenuis group in section Divaricate, Bryoria americana was used as an outgroup taxon based on the phylogenies by Myllys et al. (2011, 2016). Gene regions were aligned separately with MUSCLE v.3.8.31 (Edgar 2004) using EMBL-EBI's freely available web service (http://www.ebi.ac.uk/Tools/msa/muscle/). Maximum parsimony, maximum likelihood, and, Bayesian analyses were performed for all seven data sets.

PhyDE - Phylogenetic Data Editor: http://www.phyde.de/docu/docu.html</p>