Pseudocrossidium exiguum M.J.Cano & J.A.Jiménez (Pottiaceae), a new species from South America

Abstract

A new species of Pseudocrossidium R.S.Williams, P. exiguum M.J.Cano & J.A.Jiménez, is described from South America (Argentina, Brazil and Peru). The species is distinguished morphologically by its lingulate to oblong-ovate leaves, leaf marginal cells not or scarcely differentiated from inner, costa ending below apex or percurrent, and semicircular to elliptical in cross-section with two guide cells, scarcely differentiated perichaetial leaves and peristome of short and straight teeth. Drawings and light microscope photographs of the new species are provided. The principal distinctive characters that separate it from the nearest species of Pseudocrossidium and related genera are discussed.