DNA barcoding of Arctic bryophytes: an example from the moss genus Dicranum (Dicranaceae, Bryophyta)

The identification of bryophytes from the Arctic is often difficult due to deviating morphologies under the extreme environmental conditions. This is especially true for species-rich and taxonomically complex genera, such as the moss genus Dicranum. DNA barcoding is expected to improve the identification of Arctic bryophyte species, but the optimal combination of barcoding markers for mosses in general, especially for delimiting closely related, is still under discussion. In this paper, we test the discrimination capacity of six potential barcode markers (rps4-trnT (UGU), trnL (UAA)-trnF (GAA), trnH (GUG)-psbA, rps19-rpl2, rpoB, and nrITS1-5.8S-ITS2) based on phylogenetic reconstructions of 30 Dicranum samples from Spitsbergen (Svalbard, Norway), and reference samples from all ten Dicranum species confirmed for the Svalbard archipelago and six additional Arctic Dicranum species. All 16 species (possibly except D. fuscescens) were distinguishable with bootstrap support > 70 % based on the combined sequence data, but none of the individual markers could delimit all included species. All Svalbard collections could be readily assigned to five species, D. acutifolium, D. elongatum, D. laevidens, D. majus, and D. spadiceum, respectively. It is concluded that DNA barcoding improves species identification of Arctic Dicranum plants, but that a combination of several markers is necessary in order to obtain reliable identification results, with the single loci ITS1, trnL-F and rps4-trnT being the most promising regions.