Orthotrichum underwoodii, sp nov (Orthotrichaceae, Bryopsida) from California

A new moss species, Orthotrichum underwoodii F. Lara, Garilleti h Mazimpaka , is described from material kept in the New York Botanical Garden Herbariu m. The new taxon is included in subgenus Pulchella (Schimp.) Vitt, ar rd ch aracterized by leaf cells pluripapillose; capsule immersed, cylindric abrup tly contracted to the seta whose apical part is hidden in a hollow; opercul um conic-convex stomata cryptopore and located in the lower capsule half; c apsule with 8 short exothecial bands, comprising 2(3) cell rows; exostome w ith 16 whitish teeth receiving irregularly; and endostome with 16 segments uniseriate. Orthotrichum underwoodii is taxonomically close to O. handiense F. Lara, Garilleti & Mazimpaka recently described from the Canary Islands (Spain). Differences of the two mosses and possible confusion of the new sp ecies,with others are discussed.