From Williams et al., 2017:

[Compositosphaeridium, Erkmen and Sarjeant, 1980, p.65-66.

Name illegitimate - senior homonym: Compositosphaeridium Dodekova, 1974.
Taxonomic senior synonym: Compositosphaeridium Dodekova, by implication in Lentin and Williams (1981, p.53), who included the "type species" of Compositosphaeridium Erkmen and Sarjeant, Compositosphaeridium bulgaricum, in Compositosphaeridium Dodekova. Erkmen and Sarjeant cited the generic name as "Compositosphaeridium Dodekova, 1974" but gave the "type species" as "Compositosphaeridium bulgaricum Erkmen and Sarjeant sp. nov., nom nov. pro Compositosphaeridium costatum Dodekova, 1974, non Davey and Williams, 1966 [1966b herein] ...." Since it is illegitimate to change a designated type (I.C.B.N. Article 7.2) except through formal conservation, Erkmen and Sarjeant (1980) effectively and validly published a new generic name, Compositosphaeridium Erkmen and Sarjeant, which is illegitimate as a junior homonym of Compositosphaeridium Dodekova.

Type species: Compositosphaeridium costatum, Dodekova, 1974 (pl.1, figs.4-6, text-fig.1)] , designated by Erkmen and Sarjeant (1980, p.67).