Racomitrium hespericum from the Iberian Peninsula is described as a ne
w species of section Papillosa (Kindb.) Nog., and its diagnostic chara
cters are illustrated. It is closely related to R. aciculare (Hedw.) B
rid. Racomitrium hespericum is an aquatic moss, and its ecology is dis
cussed. The distribution of the species is mapped. It is endemic to th
e Iberian Peninsula.