Dale H. Vitt

Plants small, in loose mats, dull to bright green. Stems creeping, densely terete-foliate, occasionally subsecund, irregularly branched, branches densely foliate; central strand absent; pseudoparaphyllia narrowly acute; axillary hairs of 4-6 cells. Stem leaves appressed when dry, spreading when moist, imbricate, ovate to ovate-lanceolate, concave, not plicate, <0.4-0.7 mm>; base scarcely decurrent; margins entire, subentire to serrulate distally; apex acute to narrowly obtuse; costa to 33-66% leaf length, slender, terminal spine absent; alar cells subquadrate to oblate-quadrate in several rows, little different from more distal cells; laminal cells rhombic to oblong-rhombic, <1.5-3:1>, walls thin; proximal cells quadrate to subquadrate, shorter at margins. Branch leaves similar. Sexual condition autoicous; perichaetial leaves erect to flexuose, apex abruptly acuminate. Seta reddish, smooth. Capsule erect, brown, narrowly elliptic to oblong, symmetric; annulus not separating; operculum long-rostrate; peristome without apparent hygroscopic movement, modified; . Calyptra naked. Spores 14-21 µm.

Species 1: c, e United States, Europe.

Clasmatodon has been variously placed in Fabroniaceae or Myriniaceae, but molecular data strongly suggest a position in Brachytheciaceae as a small, epiphytic, monospecific genus with a reduced peristome.

Lower Taxon

• Clasmatodon parvulus (Hampe) Sullivant