Platyhypnidium mutatum, a mysterious new moss from Germany

Platyhypnidium mutatum Ochyra & Vanderpoorten (Brachytheciaceae) is describ ed and illustrated as a new moss species. It is known from a single localit y in a waterfall at Allerheiligen in the Black Forest in southwestern Germa ny. This is an aquatic moss closely related to P. riparioides (Hedw.) Dixon but easily recognized by its irregularly 1-3-stratose laminae with 3-5-str atose, often broad ridges irregularly scattered throughout the leaf lamina, the strong single, but frequently spurred, percurrent costa, the plane or inflexed leaf margins which are serrulate throughout or only weakly so to e ntire above the base, and the linear-flexuose to oblong-hexagonal laminal c ells. The species produces fully mature sporophytes which exhibit all typic al features of the brachythecioid mosses including ecostate inner perichaet ial leaves, relatively short, slightly inclined and asymmetric capsules, ob liquely long rostrate operculum, round-pored stomata, red-brown exostome te eth, perforated endostome processes, and appendiculate cilia.