2. Trematodon longicollis Michx. 长蒴藓 chang-shuo xian
Fl. Bor. Amer. 2: 289. 1803. Type. U.S.A.: North Carolina, Michaux s.n.
Trematodon acutus C. Müll., Syn. Musc. Frond. 1: 458. 1848.
Trematodon drepanellus Besch., J. Bot. (Desvaux) 12: 283. 1898.
Trematodon flaccidisetus Card., Beih. Bot. Centralbl. 17: 5. 1904. Trematodon drepanellus var. flaccidisetus (Card.) Dix., Hong Kong Naturalist. Suppl. 2: 2. 1933.
Trematodon paucifolius C. Müll., Syn. Musc. Frond. 1: 459. 1848.
Trematodon stristicalyx Dix., Hong Kong Naturalist. Suppl. 2: 3. 1933. Type. China: Zhejiang, Hang-zhou, E. D. Merril 1152 (holotype BM).
Trematodon tonkinensis auct. non Besch. (sensu Chinese authors).
Plants minute, 2–6 mm high, green to yellowish green, gregarious or scattered. Stems erect, simple or rarely branched. Leaves 1.7–3.6 mm long, contorted when dry, flexuose spreading when moist, oblong to oblong-ovate at base, gradually narrowed from a clasping base to a long, linear-subulate acumen, blunt at tips; margins plane and entire below, slightly recurved and serrulate above; costa strong, percurrent, not entirely filling the acumen; upper and median cells short to moderately rectangular, 18–24 µm × 8–10 µm, firm or somewhat thick-walled; basal cells in the clasping base, oblong-rhomboidal to long-rectangular, 40–90 µm × 8–13 µm, lax, thin-walled. Autoicous. Perichaetial leaves larger than the upper stem leaves. Setae straight, (4–)10–20(–30) mm long, yellow to yellowish brown; capsules inclined, urn short-cylindric, 1.5–2.0 mm long, neck 3.0–5.0 mm long, curved above, strumose at base; opercula slenderly and obliquely long-rostrate; annuli well developed, deciduous; stomata of two kinds; peristome teeth lanceolate, reddish, somewhat perforate, vertically striate on lower 2/3 of the teeth, papillose on the upper 1/3. Spores ca. 20 µm in diameter, strongly papillose.