Carboniferous foraminifers and biostratigraphy of lower Akiyoshi Limestone (Japan)

The pre-Moscovian series of Akiyoshi Limestone (Japan), from late Visean to Bashkirian, is divided into 11 biozones. The oldest biozones (1 to 7) are newly characterized in this area, (1) Mediendothyra cf. cara and Mediendothyra exilis Zone; (2) Endothyranopsis (Endothyranopsis) compressa, Rectocribranopsis hirosei, Eostaffella proikensis, and Janischewskina isotovae Zone; (3) Endothyranopsis (Endothyranopsis) compressa, Mediocris mediocris, Eostaffella ikensis, and Climacammina mixta Zone; (4) Endothyranopsis (Reitlingeropsis) sphaerica, Eostaffella ikensis tenebrosa, and Eostaffella ex gr. constricta Zone; (5) Eostaffella kamiyozawensis and Seminovella elegantula Zone; (6) Ozawainella ex gr. pararhomboidalis and Semistaffella (Praesemistaffella) sp. 1 Zone; (7) Eostaffella japonica Zone. These seven zones are Aleksian, Mikhailovian, Venevian, Venevian/Tarusian, Zapaltjubian/Voznesenian, early Syuranian, and late Syuranian in age, respectively. Then, traditional Bashkirian biozones (8-11) are successively present: (8) Pseudostaffella antiqua and Eostaffella postproikensis Zone; (9) Pseudostaffella compressa and Pseudostaffella proozawai Zone; (10) Profusulinella daiyamensis Zone; and (11) Profusulinella beppensis and Verella sp. Zone. The foraminiferal genera and species are taxonomically analyzed. The new taxa are Rectocribranopsis n. gen., Eoturrispiroides n. gen., Latiendothyranopsis okimurai n. sp., and Tetrataxis pagodatectum n. sp. The genus Nodasperodiscus and the species Rectocribranopsis hirosei (Okimura, 1963), often misinterpreted in the literature, are re-described