Cryptic and morphologically recognizable species diversity within Scandinavian Plagiopus oederianus (Bryophyta: Bartramiaceae)

Based on studies of the nuclear marker ITS, the plastid ones atpB-rbcL and rpl16, and morphology, five species are recognizable within Scandinavian Plagiopus oederianus. Four of these species are cryptic, whereas the fifth one, Plagiopus alpinus (Schwaegr.) Hedenäs, comb. et stat nov., can be distinguished from the other ones by morphology. Plagiopus alpinus is smaller than the four cryptic species within P. oederianus and has smaller spore capsules, smaller exothecial cells, shorter leaves and shorter lamina cells in the middle and base of the leaves. In Scandinavia, P. alpinus occurs in the mountain range, whereas the cryptic species within P. oederianus occur both in the mountains and in the lowlands. Outside Scandinavia, P. alpinus is known from the European Alps but it seems likely that it is widespread in mountains and northern regions of the northern hemisphere. The cryptic species within P. oederianus differ in several molecular bases.