Bathycyathus Milne Edwards & Haime, 1848

Baron-Szabo, Rosemarie C., 2008, Dendrophylliina, Caryophylliina, Fungiina, Microsolenina, and Stylinina, Zootaxa 1952, pp. 1-244 : 52

Genus Bathycyathus Milne Edwards & Haime, 1848

(= Monticyathus Alloiteau & Tissier, 1958 , Type species. Monticyathus lehmani Alloiteau & Tissier, 1958 , Danian of Belgium);

(= Coronocyathus Alloiteau &Tissier, 1958 , Type species. Coronocyathus goffinti Alloiteau & Tissier, 1958 , Danian of Belgium);

(= Frescocyathus Barta-Calmus, 1969 , Type species. Frescocyathus tessieri Barta-Calmus, 1969 , Paleocene of Ivory Coast);

(= Steriphonotrochus Vaughan, 1900 , Type species. Steriphonotrochus pulcher Vaughan, 1900 , Oligocene of the USA [Red Bluff, Mississippi]).

Type species. Bathycyathus chilensis Milne Edwards & Haime, 1848c , Recent , Pacific Ocean (off the coast of Chile) .

Diagnosis. Solitary, turbinate or variably conical, fixed or free. Often circular in outline in juvenile stages, becoming compressed in later ontogenetical stages. Costosepta laminar, compact. Septal margins smooth or nearly smooth. Pali not distinct from columellar laths. Columella formed by twisted trabecular segments. Endothecal dissepiments few in number. Wall septothecal, septoparathecal when not properly thickened.

Remarks. Alloiteau & Tissier (1958) stated that their newly created genus Coronocyathus was characterized by 1) a parathecal and septothecal wall, 2) laterally finely dentate compact costosepta, 3) pali opposite S1 and S2, 4) a spongy columella forming twisted segments, and 5) the lack of both endothecal developments and synapticulae. However, in contrast to this statement the illustrations of the type material ( Alloiteau & Tissier, 1958, pl. 1, figs 5 a–e) indicate that the specimens are characterized by a rather septothecal wall throughout their ontogenetical development, show a small number of endothecal dissepiments, and have paliform structures which, especially in younger ontogenetical stages, are not distinct from columellar developments. Therefore, the assignment to the genus Bathycyathus is suggested.

Alloiteau & Tissier (1958) created the genus Monticyathus . The illustrations of the type specimen differ from the description of the holotype in that there are dissepiments and rather septothecal (septoparathecal in places) developments present, whereas the authors stated that an endotheca was absent and a parathecal wall was present. In addition, the illustrations of the holotype show a turbinate corallum, that has a spongy-net-like columella, and pali that are generally fused with columellar segments. Therefore, the assignment to the genus Bathycyathus is suggested.

Barta-Calmus (1969) created the genus Frescocyathus from the Paleocene of Ivory Coast, stating that it differed from Bathycyathus in having a trochoid-shaped corallum and a weakly developed columella. Because in Bathycyathus the corallum shape is most likely largely controlled by its mode of attachment, due to which the corallum later becomes fixed or free, and the size of the columella that can be strongly or weakly developed, the assignment of Frescocyathus to the genus Bathycyathus is suggested.