Fabronia Raddi, Atti Accad. Sci. Siena

Fabronia Raddi, Atti Accad. Sci. Siena View in CoL 9: 231–235, pl. 1. 1808.

Plants very small, soft, forming small flat mats, green or yellowish green, silky. Stems fragile, prostrate, irregularly branched, branches short, mostly densely foliate, julaceous; central strand and hyalodermis not differentiated, all cells ± thin-walled; rhizoids clastered near branch bases and developed on dorsal side of costa in lower part of leaves; paraphyllia absent; juvenile branch leaves narrow lanceolate or linear, sutuated on branch bases. Leaves loosely appressed when dry, occasionally slightly secund, spreading when moist, concave, ovate, ovate-lanceolate or lanceolate, abruptly or gradually acuminate, often piliferous; margins plane, dentate, denticulate or subentire, marginal teeth unicellular, short or long, or large, multicellular; costa slender, ending at midleaf; lamina unistratose, smooth; leaf cells rhomboidal or long-rhomboidal, with moderately thickened, non-porose walls; alar cells differentiated, quadrate and short rectangular, numerous. Autoicous. Perichaetial leaves broader than vegetative leaves. Setae erect, slender, yellowish or brownish, smooth. Capsules erect, ovoid, pyriform or cylindrical; annulus absent; exothecial cells quasrate and short rectangular, with wavy walls, stomata present, with elongate pore; peristome single, consisting of 16 exostome teeth usually fused in pairs, broadly lanceolate, blunt, light brown or dark red-brown, densely papillose-striolate on both surfaces, without trabeculae on both sides, usually reflexed when dry and appressed to the capsule wall, fragile, often broken in opened capsules. Opercula low conic or almost flat, mammillate or obliquely rostrate. Spores small, smooth or finely papillose.