8. Trachycystis Lindberg, Not. Sallsk. Fauna Fl. Fenn. Förh. 9: 80. 1868. • [Greek trachys, rough, and cystis, bladder or bag, alluding to mammillose laminal cells].
Jillian D. Bainard, Terry T. McIntosh
Plants (0.7-)1-2.5 cm, in loose tufts or mats. Stems brown or reddish brown, erect, branches few, short, not dendroid; rhizoids reddish brown, macronemata and micronemata present proximally on stem. Leaves green, incurved upwards, crisped or contorted when dry, erect-spreading, flat, or weakly keeled when moist, ovate-elliptic or sometimes elliptic, (1.5-)2.2-2.6 mm; base decurrent; margins plane, green, pale brown, or sometimes reddish, 2-stratose, toothed to below mid leaf, sometimes to base, teeth usually paired and sharp, sometimes single; apex acute or acuminate, usually cuspidate, cusp often lightly toothed; costa percurrent, distal abaxial surface toothed; medial laminal cells short-elongate or ± isodiametric, (9-)12-18 µm, often in longitudinal rows, mammillose on both surfaces, strongly collenchymatous, walls not pitted; marginal cells differentiated, linear, in 1-2(-3) rows. Specialized asexual reproduction as flagelliform branches, often copious, 2-4 mm, from distal leaf axils, with small, appressed leaves. Sexual condition dioicous. [Seta single, red, 2-3 cm, flexuose. Capsule horizontal to pendent, yellowish brown, cylindric, 2-3 mm; operculum conic or short-rostrate; exostome yellow to yellowish green; endostome reddish brown. Spores 20 µm].
Species 3 (1 in the flora): Alaska, Europe, Asia; circumtemperate.
Trachycystis is distinguished from other genera in Mniaceae by mammillose laminal cells and asexual reproduction by flagelliform branches. Characteristics of the sporophyte, as presented here, are taken from Li X. J. et al. (2007) and from examination of Asian material.