Didymodon vulcanicus J.A.Jiménez, Hedd. & Frank Müll. (Pottiaceae), a new species from tropical Africa

Didymodon vulcanicus J.A.Jimenez, Hedd. & Frank Mull. is described and illustrated as a new species from volcanic regions of tropical Africa. The species is distinguished morphologically by its lanceolate or more rarely ovate-lanceolate leaves that are strongly incurved distally when dry, acute apices, upper and middle laminal cells arranged in longitudinal rows with a low dorsal papilla over the transverse walls which reaches the two immediate cells, basal cells not or hardly differentiated from the medial cells, and the presence of gemmae in the leaf axils. Drawings and light microscope photographs of the main characters are given, and possible confusion with other closely related taxa is discussed.