Molecular and morphological studies on the Didymodon tophaceus complex

Abstract

Recently two Mediterranean species closely related to Didymodon tophaceus (Brid.) Lisa have been described in the genus Didymodon Hedw.: Didymodon sicculus M. J. Cano et al. and Didymodon erosus J. A. Jiménez & J. Guerra. The former has been proved to be widespread around the Mediterranean basin in recent years, and this study points to a considerable extension of its distribution area towards north, since it has also been discovered in the Netherlands. D. erosus, with its narrow morphological characterization, was only described four years ago and has hitherto only been known from the original localities in Spain. The molecular study based on nrITS sequence data of some selected specimens of all the three species suggests that D. erosus is much more frequent and widespread in Europe than supposed and, furthermore, is morphologically much more variable than previously described. A key for the identification of the three species, an amended description of D. erosus and a map showing the known distribution area are presented.