Thamnobryum angustifolium (Holt) Nieuwl. in the Maritime Alps, new to Italy

ABSTRACT Introduction Thamnobryum angustifolium (Holt) Nieuwl. is an endemic European species at high risk of extinction and included in British and International red lists. It was previously known only from two localities in England, UK. We report here the discovery of a moss very similar to T. angustifolium during surveys of aquatic vegetation along the bed of the Gesso stream, near Valdieri village, Gesso della Valletta Valley, Maritime Alps, Piedmont, Italy. Methods Material from the new locality was compared morphologically with material from Derbyshire and Cumberland (now combined with Westmorland to form Cumbria) in England and with the adjacent population of Thamnobryum alopecurum (Hedw.) Gangulee. The Italian material resembling T. angustifolium was also investigated using nuclear (ITS2) and plastid (rbcLa and trnH–psbA) markers. The sequences obtained were compared with data available in GenBank. Key results and conclusions Morphologically, the material from the Italian population is very close to the English populations, especially the one from Cumberland, but there are minor differences between all three populations. The differences are not considered sufficient to merit the description of a new taxon. Thamnobryum angustifolium is therefore new to Continental Europe. Analysis of the molecular data revealed no genetic differences between Italian T. angustifolium and the adjacent population of T. alopecurum. This supports the proposition that the populations of T. angustifolium in England and Italy are derived independently from the surrounding populations of T. alopecurum at each of the localities.