During the course of a review of section Aloma C. Miill. for a monograph of the neotropical species of Fissidens, a specimen from southwestern Colombia thought initially to represent a variant of F. laxus Sullivant & Lesq. (including F. pellucidus Hornsch. and F. flexinervis Mitten) was found on closer examination to have a number of unusual characteristics. Thus we propose the following new species to accommodate this collection.