Data from: Macromtrium longipapillosum, a new species of Orthotrichaceae (Bryophyta) from Japan, with comments on M. comatum Mitt.

Here we report a new species, Macromtrium longipapillosum, from Japan, and illustrate it by line drawings and photographs. The new species can be distinguished from all congeners by a combination of the following features: 1) lanceolate to oblong-lanceolate leaves with obtuse, acute to broadly acuminate apices; 2) upper and median laminal cells with thin and inflated walls, with a single, large, occasionally forked papilla, 7-14 μm, occasionally up to 18 μm, 3) basal cells near costae forming a “cancellina region”, 4) inner perichaetial leaves ovate lanceolate, abruptly narrow to an long acuminate upper parts; 5) short and left-twisted seta; and 6) obloid capsules with well-developed exostome teeth. We also revise the circumscription of Macromitrium comatum Mitt. and discuss relationships of M. comatum with M. longipapillosum and other relevant species.