9. Ptychomitrium wilsonii Sull. & Lesq. 威氏缩叶藓 wei-shi suo-ye xian
Proc. Amer. Acad. Arts Sci. 4: 277. 1859. Type. Japan.
Brachysteleum evanidinerve Broth., Sitzungsber. Akad. Wiss. Wien Math. Nat. Kl. Abt. 1, 131: 211. 1923. Type. China: Hunan, Chang-sha City, Handel-Mazzetti 12783 (holotype H-BR).
Plants medium-sized to rather large, 2–3(–4) cm high, green above, black-green below, sometimes black-brown throughout, in loose tufts. Stems simple or sparsely branched; central strand well developed. Leaves 3.9–4.1 mm long, incurved when dry, spreading to erect-spreading when moist, oblong-ovate to broadly oblong-lanceolate, slightly keeled or plane above, broadly acute or obtuse at the apex; margins plane, irregularly toothed in the upper half ; costa single, strong, gradually narrowed above, subpercurrent or ending just below the apex; upper leaf cells obscure, rounded quadrate to subquadrate, 10–13 µm wide, with slightly thickened walls; basal cells elongate, 35–70 µm × 8–11 µm, hyaline, thin-walled; alar cells often brownish. Autoicous. Perichaetial leaves similar to the upper stem leaves. Setae straight, yellow, ca. 4.5 mm long; capsules erect, ovoid to oblong-ovoid, ca. 1.5 mm long; annuli undifferentiated; peristome teeth lanceolate, split into 3–4 divisions nearly to the base, yellow above, reddish brown below, finely papillose throughout; opercula conic-rostrate, with a long, erect beak. Calyptrae mitrate, covering the middle to lower part of capsules, longitudinally plicate, lobed at base. Spores yellowish green, 25–30 µm in diameter, finely papillose.