Abstract
A new moss genus and species, Gradsteinia andicola, is described from the northern Andes of Colombia. It is an aquatic moss known sterile and characterized by 1) oblong or oblong-ovate, concave, cucullate and recurved-apiculate leaves with a very strong and variable costa that is basically single but commonly repeatedly branched and spurred from the base, giving the leaves a polycostate appearance; 2) thick-walled, porose and irregularly uni- to multistratose lamina cells; 3) bicellular axillary hairs; 4) the presence of incomplete limbidia; 5) the absence of paraphyllia, pseudoparaphyllia, central strand and alar cells. Until the sporophyte of Gradsteinia becomes known, this very distinct genus is tentatively placed in the family Donrichardsiaceae, based primarily upon the presence of variously multistratose leaf laminae and leaf areolation.