Japanese species of the sect. Riccia of the genus Riccia (Ricciaceae, Hepatics) were taxonomically revised and four species were recognized: they are R. beyrichiana Hampe ex Lehm., R. bifurca Hoffm, R. glauca L., and R. subbifurca Warnst. ex Croz. Most specimens previously named by Japanese bryologists as R. glauca are revealed to be R. bifurca, which is commonly distributed from Hokkaido to Kyushu. Riccia glauca is, on the contrary, very rare in Japan. Both R. beyrichiana and R. subbifurca are newly reported from Japan. Descriptions, diagnostic characters, distribution and illustrations of these four species are provided based on Japanese plants.

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Male plants and sporophytes of Yakushimabryum longissimum are newly reported based on plants collected in Yakushima Island. Additional localities of the species outside the island were confirmed from Japan (Tokyo Metr., and Kagoshima Pref.), Taiwan (Taichung Co. and Miaoli Co.), Malaysia (Pahang), and Vietnam (Vinh Phuc). Morphological differences in the manner of serration at the base of leaf margins and shape of the cells composing filamentous propagules between Y. longissimum and Gammiella tonkinensis are briefly discussed.

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Two new species, Aptychella pseudobrevinervis and A. oblongifolia are described based on specimens collected from Doi Inthanon, northern Thailand and Guizhou Prov., southwestern China. Both species are characterized by a single, long costa in the leaves. The two new species share more or less decurrent leaf bases, which are absent in the other costate species, A. brevinervis, but differ from each other in plant size and leaf shape. Peristome teeth of A. oblongifolia are not perforate and this is the first record of such a condition for the genus.

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