N51

Notes on the Genera Theocalyptra and Cycladophora

Riedel (1971) pointed out that the Family Theoperidae is a large, probably polyphyletic taxon of which there is, as yet, no satisfactory division into subfamilies. In the absence of such a revision it is necessary to approach taxonomic problems with caution and conservatism. What is fixed and relatively immovable is the concept of type species and that must be the starting point of any taxonomic considerations. With these thoughts in mind, consider the generic placement of the species variously described as Theocalyptra davisiana (Ehrenberg) and Cycladophora davisiana Ehrenberg. The type species of Theocalyptra is T. veneris Haeckel (1887, p. 1397); the type species of Cycladophora is C. tabulata Ehrenberg (1872b, pl. 4, fig. 18). Unfortunately, neither of these type species is entirely satisfactory.

T. veneris was described, but not illustrated by Haeckel. However, he does say that the species is similar to Eucephryphalus agnesae (pl. 59, fig. 3). But this species is not known. Haeckel probably means Corocalyptra agnesae which is the name of the species illustrated on plate 59, fig. 3. If one assumes then that the illustration on plate 59, fig. 3 is very like the type species of Theocalyptra, it may be argued that Theocalyptra veneris is similar to Theocalyptra bicornis and T. bicornis is similar to davisiana. Therefore, the appropriate generic assignment might be Theocalyptra. This line of reasoning was used by Riedel (1958).

Cycladophora tabulata Ehrenberg is poorly illustrated (1872b, pl. 4, fig. 1) and is somewhat similar to davisiana, but not at all like bicornis. In fact, Ehrenberg questioned the placement of davisiana in the genus Cycladophora. However, in the absence of a complete revision it could be argued that one should return to the original generic designation, i.e., Cycladophora davisiana. This line of reasoning was used by Petrushevskaya (1967).

Observations have suggested that bicornis and davisiana are sufficiently similar as to be placed in the same genus and hence the genus Theocalyptra is used herein. A detailed study of these forms is needed to finally resolve the taxonomy of these species.