The hairs of Leptogium species are complex structures which determine taxonomic groups within the section Mallotium. The hairs composed of cylindrical cells can be short and, when present on the surface, give origin to glass-or velvet-like hairs. Leptogium involutum, collected in Southern Brazil, a new species with velvet-like hairs is described herewith.
cylindrical cells; involute margin; Leptogium velutinum
