A REVISION OF THE MOSS GENUS CROSSIDIUM (POTTIACEAE) WITH THE DESCRIPTION OF THE NEW GENUS MICROCROSSIDIUM

A world revision of the genus Crossidium JUR. recognizes 11 species, w hich are described and discussed in the context of important taxonomic characters. An identification key is provided. C. asirense FREY & KUR SCHNER is reduced to synonymy with C. davidai CATCHESIDE, and the geog raphical range of C. laevipilum THER. & TRAB. is extended to Europe. P hylogenetic trends are interpreted on the basis of two main evolutiona ry lines associated with the presence or absence of hyaline hair-point s on the leaves. A twelfth species is transferred to Microcrossidium G UERRA & CANO, gen. nov., as M. apiculatum (MAGILL) GUERRA & CANO, comb . nova, because of differences in stem anatomy, peristome configuratio n, and spore morphology.