Schistidium deguchianum (Grimmiaceae), a new Andean species from Peru

Schistidium deguchianum Ochyra & Bednarek-Ochyra is described and illustrated as a new rheophytic species from the Andes of Peru. The species is easily distinguished from all congeners in having entirely bistratose laminal cells with some unistratose patches near the leaf base and 3-4-stratose strands in the distal half. Additionally, it is characterized by its largely concave leaves, plane and erect leaf margins that are bistratose to the extreme base and 3-4-stratose in the distal half, forming fleshy, and somewhat bulging limbidia, entire to distantly, bluntly serrulate near the apex, nearly homogeneous leaf areolation of small, rounded, rounded-quadrate to transversely elliptical cells arranged in regular longitudinal rows, unistratose perichaetial leaves with only some bistratose streaks near the apex, thin-walled exothecial cells, capsules lacking stomata, erect and straight peristome teeth, and minutely papillose, small spores, 10-12 mu m wide. The affinities of S. deguchianum are discussed and the species is placed in Schistidium Bruch & Schimp. subgen. Canalicularia Ochyra. The status of S. rivulariopsis (R. S. Williams) Ochyra is briefly assessed and it is reinstated as a good species, distinct from S. rivulare (Brid.) Podp.