Plants minute, 2–4 mm high, yellowish green, in loose tufts. Stems simple or sparsely branched; central strand absent. Leaves abruptly long-subulate from an oblong to ovate, sheathing base, 1.1–1.9 mm × 0.25–0.35 mm; margins entire to serrulate from the shoulder to the apex; costa percurrent; upper cells rhomboidal to linear, 26–40 µm × 8–10 µm, thick-walled; lower cells rectangular to linear-rectangular, 26–70 µm × 11–14 µm, thin-walled. Paroicous. Perichaetial leaves larger, up to 2.0–2.5 mm long. Setae yellowish to yellowish brown, erect, 0.7–1.1 mm long; capsules immersed, obovoid, 1.0–1.3 mm long, neck 0.2–0.3 mm long, tapered at the base. Calyptrae mitrate, smooth, lobed at the base. Spores yellowish green, 31–33 µm in diameter, spinose.

Type. Japan: K. Mayebara 678.

Chinese specimens examined: GUANGDONG: P.-C. Chen s.n. (IFSBH, PE).

Habitat: on soil in open fields; Distribution: China and Japan.

Rushing and Snider (1985) confirmed that the type specimen of this species from Japan (Mayebara 678, NICH) was a mixed collection of Bruchia microspora and a hybrid, Bruchia microspora × Trematodon longicollis Michx. The Chinese specimen of this species also contains the hybrid, which can be readily identified by the rudimentary development of the peristome and red annuli, and by the setae (1.0–1.8 mm long) longer than that of the typical B. microspora.

Illustrations: Pl. 23, figs. 1–9.