Anthoceros subtilis Steph., Spec. Hepat. 5 (1916) 1003. Anthoceros subbrevis Haseg., Journ. Hattori Bot. Lab. 57 (1984) 261.
Diagnostic characters—Plants forming rosettes, deep-green; thalli orbicular, cavernous; margins lobulate, crispate; rhizoids numerous ventrally; epidermal cells of thalli quadrate, thin-walled, with one large chloroplast. Autoicous. Androecia scattered, with 4-5 antheridia in a cavity, antheridia rounded-ellipsoid; involucres erect, shortly cylindrical, up to 2 mm long; capsules up to 10 mm long, 2-valved dehiscent, twisted in upper parts, with stomata; epidermal cell of capsules elongate-rectangular, thick-walled; spores spherical, distinct triradiate lines, dark brown to blackish upper hemisphere sparsely echinate-spinose, lower hemisphere densely so; spines c. 2 micrometer long; pseudoelaters (1-), 2-4 celled, short, quadrate to rectangular, thick-walled, dark-brown to blackish, up to 15 micrometer diameter.
Ecology—on roadside soil, in disturbed areas in primary, evergreen, seasonal, hardwood forest, granite bedrock; Pu Ping Place, c. 1,374 m elevation; on soil in mixed evergreen+ deciduous, seasonal, hardwood forest, granite bedrock, Sirindhorn Observatory area, c. 850 m elevation.
Distribution—Japan and Thailand (Hasegawa, 1984).
Specimens examined—Printarakul 5013, 5454, 5457, 6450; Manachit 188 (all CMU).
Note—This species can be recognized by the elongate capsules, up to 1 cm long; spores dark brown to blackish, upper hemisphere sparsely echinate-spinose, lower hemisphere, densely so; spines c. 2 micrometer long; pseudoelaters short, quadrate to rectangular c. 15 micrometer diameter.
