AbstractPorothamnium frahmiiEnrothsp. nov. (Neckeraceae, Musci), known from Colombia and Peru, is described and illustrated. It is compared withPorotrichum substriatum(Hampe) Mitt.,P. longirostre(Hook.) Mitt.,Porothamnium filiferum(Mitt.) Fleisch., andP. expansum(Tayl.) Fleisch., with which it might be confused. The sporophyte ofPorotrichum substriatumis described for the first time.Porothamnium stipitatum(Mitt.) Touw ex De Sloover, previously known only from Africa, is reported from French Guiana.