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Description

<b>Abstract</b><br/>

The fruticose lichen genus <em>Gowardia</em> (Parmeliaceae) was recently segregated from Alectoria based on phylogeny, morphology, secondary chemistry, ecology and distribution. As currently circumscribed, <em>Gowardia</em> comprises two wide-ranging species of arctic-alpine regions. Here we describe a third species, <em>G. zebrina </em>sp. nov., apparently endemic to subalpine regions in mountainous northwestern North America. <em>Gowardia</em> <em>zebrina</em> differs from other species in the genus by its combined subpendent habit, uniformly capillary branches, predominantly isotomic branching, pale-and-dark banding of the terminal branches, and epiphytic ecology. Morphological examination of North American herbarium specimens filed under <em>A. nigricans</em> suggests the existence of several additional undescribed species of <em>Gowardia</em>. A brief overview of morphological diversity in these species is given, shedding new light on the question of whether <em>Gowardia</em> should be subsumed under <em>Alectoria</em>, as some have suggested, or is more appropriately recognized as a distinct genus.</p>; <b>Methods</b><br />

Phylogenetic study was based on sequences of nuclear ribosomal ITS regions from 29 specimens, including four specimens from the genus <em>Alectoria</em> and 24 specimens from <em>Gowardia</em>. <em>Bryocaulon divergens</em> (Ach.) Kärnefelt belongs to the Alectorioid clade <em>sensu</em> Divakar et al. (2015) together with <em>Alectoria</em> and <em>Gowardia</em> and was used as an outgroup. Seven new ITS sequences were generated for this study. The remaining sequence data were obtained from the NCBI GenBank (<a href="http://www.ncbi.nlm.nih.gov/genbank/">www.ncbi.nlm.nih.gov/genbank/</a>), including all available ITS sequences of <em>Gowardia</em>. The ITS sequences were aligned with MUSCLE v.3.8.31 (Edgar 2004) using EMBL-EBI’s freely available web service (<a href="http://www.ebi.ac.uk/Tools/msa/">http://www.ebi.ac.uk/Tools/msa/</a> muscle/). Phylogenetic relationships were inferred using maximum likelihood (ML) as optimality criteria. The ML analysis was performed in RAxML v.8.1.15 (Stamatikis 2104) located at CSC – IT Center for Science (<a href="http://www.csc.fi/english">http://www.csc.fi/english</a>). We divided the data set into three partitions (ITS1 region, 5,8S gene, ITS2 region) and used a GTRGAMMA model because GTR is the only substitution model implemented in RAxML. Nodal support was estimated with 1000 bootstrap replicates using the rapid bootstrap algorithm.</p>