From Williams et al., 2017:

[Ovum, Eisenack, 1931, p. 110

Name not validly published since it coincides with a morphological term and is thus contrary to I.C.B.N. Article 20.2. Ovum is Latin for egg. According to Fensome et al., 1990: "In giving the heading `Ova hispida Lohm.`, Eisenack, 1931 was clearly referring to the inadmissible two-word, unhyphenated generic name Ovum hispidum apparently proposed by Lohmann, 1904. However, by giving citations such as `Ovum hispidum longispinosum n. subsp.` it is clear that Eisenack, 1931 considered Ovum (al. Ova) to be a generic name and Ovum hispidum (al. Ova hispida) to be a specific name. Ovum hispidum can thus be considered the single (and type) species assigned to Ovum by Eisenack, 1931, a description being provided on his p.110.

Type species: Ovum hispidum, Eisenack, 1931 (an invalid name). Type: not designated]