3. Leptocladiella Fleisch. 薄壁藓属 bao bi xian shu
Musci Buitenzorg 4: 1205. 1923.
Plants small to medium-sized, dense, olive green to yellowish green, slightly glossy. Main stems prostrate; in cross section central strand absent, the inner cortex of thin-walled parenchyma cells surrounded by a sterome of smaller, thick-walled cells, and an outer hyalodermis of large, thin-walled cells. Secondary stems erect or slightly curved, 1–2-pinnately branched, with shortly arcuate branchlets; paraphyllia absent; pseudoparaphyllia lanceolate; rhizoids rarely persistent on stems and branches. Stem leaves differentiated from branch leaves; stem leaves appressed when dry, spreading when moist, broadly rounded ovate or ovate, slightly concave, weakly plicate, acuminate or acute at apex, sometimes slightly auriculate at base, clearly narrowly decurrent; margins plane or reflexed at base, sometimes entire or serrate above; costae double, short or faint, 1/6–1/3 the leaf length; laminal cells linear, curved, approximately 9–15:1, smooth, upper leaf cells slightly thick-walled; lower cells gradually becoming shorter, slightly incrassate, not or slightly pitted; alar cells clearly differentiated, isodiametric to oblong, often inflated, hyaline, loosely arranged, decurrent; branch leaves smaller than stem leaves, dense, ovate, oblong-ovate or ovate-lanceolate, acute or acuminate at apex, decurrent at base; margins serrate or dentate above, entire and reflexed below; costae double, stronger than that of stem leaves, extending 1/3 to 1/2 the leaf length, when single often forked, with one branch much longer than the other and usually ending in a spine; laminal cells smooth or prorate, alar cells differentiated. Dioicous. Perichaetia on main stems. Setae slender and elongate, reddish brown, smooth; capsules suberect or inclined, nearly symmetric, oblong-ovoid, not plicate when dry, not constricted below the mouth; exothecial cells isodiametric, sometimes oblong, unevenly incrassate; stomata superficial at base; annuli not differentiated; opercula shortly rostrate; peristome double; exostome teeth lanceolate, yellowish, bordered at margins, outer surface cross-striate, inner surface irregularly striate; endostome segments light yellow, papillose; basal membrane 1/3–1/2 the length of segments, not perforated or narrowly perforated along median line; cilia 1 or reduced. Spores spherical, finely papillose, 12–18 µm in diameter.