1. Fissidens angustifolius Sull., Proc. Amer. Acad. Arts. 5:275. 1861.
Fissidens dixonianus Bartr., Bishop Mus. Occas. Pap. 19(11): 220. 1948.
Fissidens diversiretis Dix., Proc. Linn. Soc. New South Wales 55: 270. 1930, hom. illeg.
Plants small, dark green. Leafy stems usually simple, 2–3 mm long, 1.3–1.6 mm wide; cortical stem cells small, thick-walled; axillary hyaline nodules not differentiated; central strand not differentiated. Leaves in 4–5 pairs, more or less densely foliated; upper leaves much larger than lower leaves, narrowly lanceolate to lanceolate, 1.1–1.9 mm × 0.24–0.36 mm, acute at the apex, base of dorsal laminae wedge-shaped, not decurrent; margins of apical laminae weakly serrulate by projecting cells; vaginant laminae about 1/2 the leaf length; costa of upper leaves percurrent; cells at apical laminae quadrate to hexagonal, each with a small papilla, 6.5–10.3 µm long, thin-walled; limbidia throughout leaf margins, composed of 3 rows of hyaline, elongate, smooth cells on the vaginant laminae, 1–2 rows on the apical laminae. Rhizoautoicous. Male stems at base of female stems, short; antheridia terminal. Archegonia terminal. Setae 2.0–2.8 mm long, smooth; capsules cylindrical, symmetrical; urn 0.30–0.51 mm long; peristome teeth 0.14–0.16 mm long, 32–36 µm wide at base, spirally thickened above, with large scattered papillae at middle, minutely and densely papillose below; exothecial cells quadrate, thin-walled, collenchymatous; opercula rostrate, 0.40–0.53 mm long. Calyptrae campanulate, 0.53–0.59 mm long, covering opercula. Spores 12.9–17.4 µm in diameter.
Type. Cuba: C. Wright s.n., Sullivant’s Musci Cubenses 18.
Chinese specimen examined: YUNNAN: Xishuangbanna, Meng-la Co., near power station, J.-X. Xi 1025 (HKAS, NICH).
Habitat: on soil; 600 m alt; Distribution: China, Fiji, Samoa, New Caledonia, throughout the Americas.
Fissidens angustifolius is easily distinguished from other species of sect. Fissidens, which has limbate leaves, by its unipapillose laminal cells.
Illustrations: Iwatsuki and Suzuki 1996 (Fig. II, 1–24).