Scandinavian members of the acrocarpous moss genus Oncophorus were revised after field observations had suggested unrecognized diversity. Based on molecular (nuclear: internal transcribed spacers 1 and 2, ITS; plastid: trnGUCC G2 intron, trnG, rps4 gene + trnS-rps4 spacer, rps4) and morphological evidence, four morphologically distinguishable species are recognized, Oncophorus elongatus (I.Hagen) Hedenäs, O. integerrimus Hedenäs sp. nov. (syn. O. virens var. elongatus Limpr.), O. virens (Hedw.) Brid., and O. wahlenbergii Brid. (O. sardous Herzog, syn. nov.). Oncophorus elongatus was earlier recognized, but much of its variation was hidden within O. wahlenbergii. Its circumscription is here expanded to include plants with long leaves having mostly denticulate or sharply denticulate upper margins and with long and narrow marginal cells in the basal portion of the sheathing leaf lamina. The new species O. integerrimus sp. nov. differs from O. virens in having more loosely incurved leaves and entire or almost entire upper leaf margins. Besides these characters, the species in the respective pairs differ in quantitative features of the leaf lamina cells. Several cryptic entities were found, in several cases as molecularly distinct as some of the morphologically recognizable species, and phylogeographic structure is present within O. elongatus and O. virens.
Geographic differentiation, habitat differences, morphology, Oncophorus integerrimus, Hedenäs sp. nov., Principal Component Analysis.