A new species of Lejeuneaceae collected in Guadeloupe and Dominica, Prionolejeunea grollei, is described and illustrated.The main diagnostic characteristic of the species is the obconical perianth with cristate keels formed by long ciliae and laciniae restricted to the apex. Additionally, it is recognized by asymmetrical-ovate leaves with acute to acuminate apex, large median leaf lobe cells and leaf margins usually slightly crenulate. The new species is morphologically related to P. decora (Taylor) Steph. and P. guadalupensis (Lindenb.) Steph.; a comparison between the three taxa is presented.