HEDENÄS, L., T.HEDDERSON, O.I. KUZNETSOVA , E.I. IVANOVA & M.S. IGNATOV. 2019. Orthothecium lapponicum: a disjunctive Circum-Holarctic species

Arctoa (2019) 28: 159–166

doi: 10.15298/arctoa.28.13

Orthothecium lapponicum, considered by many authors as a mere infraspecific taxon of the widespread O. chryseon, was subsequently shown to be a morphologically distinct species. Initially known only from the mountains of Northern Sweden, subsequent investigations revealed its occurrence also in Spitsbergen. Here we document its further distribution on Ellesmere Island in Canada, and in the Verkhoyansk and Chersky Mountains of Yakutia. Molecular phylogenetic analysis of the nuclear ITS region showed that specimens of Orthothecium lapponicum from Europe, Asia and North America are fully identical and highly supported as a discrete clade in Bayesian and maximum parsimony analyses, supporting its status as a good species. Descriptions and illustrations are given in order to facilitate further discovery of the species, although the very restricted range of the species seems to be real, and not simply an artifact of undercollecting or lack of recognition.