Genus Rotiphyllum Hudson, 1942.

Type species: Densiphyllum rushianum Vaughan, 1908; Upper Viséan of Ireland.

Diagnosis: Antiphylline coral with major septa meeting near corallite axis. Cardinal septum reaching corallite axis along cardinal fossula in all growth stages, shortened on calice wall but long on floor; counter septum commonly thicker and slightly longer than adjacent major septa; major septa evenly spaced, with extra thickening in inner third of their length, forming a dense axial structure; minor septa short; tabularium normal, sometimes weakly biform in some septal loculi. (Fedorowski, 2004, slightly modified by Fedorowski, 2009a).

Remarks: Generic relations of Rotiphyllum were widely discussed by authors, among them Weyer (1975, 1977), Fedorowski (1987a), and Wang (1994) who supported Fedorowski’s concept of the genus. Fedorowksi (1987a) especially discussed the relation to Bradyphyllum and stressed the difference of Rotiphyllum by its long cardinal septum along the fossula floor, though, later, Fedorowski (2004) stated the very close relationship of both genera. The synonymy of Actinophrentis, unambiguously synonymised by Weyer (1975) and also supposed by Hill (1981) was rejected by Fedorowski (1987a; see above under Actinophrentis), who also rejected the conclusion of de Groot (1963), Weyer (1975), and Hill (1981) that Monophyllum Fomichev, 1953 would be a junior synonym of Rotiphyllum Hudson, 1942 (see above under Monophyllum), (Table 1). Finally, Fedorowski (1989; updated in Fedorowski, 2009a) gave an extensive review on the synonymy, the included species and the relations of the genus. According to the extended number of species attributed by him, the very long stratigraphical range from the Tournaisian throughout the Lower Permian— and even the middle Permian in Japan (fide Wang et al., 2017)—and geographical distribution from the British Isles and the westernmost Palaeotethys (northern Spain) to northeastern China and the peri-Gondwana terranes from Tibet to Yunnan (judged from Fedorowski’s synonymy list and complemented by Wang et al., 2017), Rotiphyllum might be a waste basket of morphotypes belonging to different taxa. It appears to be absent from the Cordilleran–Arctic–Uralian realm (Wang et al., 2017).