From Fensome et al., 2019:

"Meristaulax", Brenner, 1988, p.65.
Name illegitimate -- senior homonym: Meristaulax Sarjeant, 1984a.
Taxonomic senior synonym: Cribroperidinium, by implication in Jan du Chêne et al. (1986a, p.76) and Lentin and Williams (1993, p.423), who listed Meristaulax Sarjeant as a taxonomic junior synonym of Cribroperidinium on the basis of the morphology of Sarjeant's lectotype of Meristaulax granulata, which is now the type of Meristaulax Brenner. Brenner (1988, p.65) cited this genus as "Meristaulax Sarjeant 1984". However, he listed as "type species" "Meristaulax granulata Sarjeant 1984" with the specimen illustrated by Sarjeant (1984a, pl.3, figs.3–4) as holotype, and clearly separated this species from Meristaulax granulata (Klement, 1960) Sarjeant, 1984a, with Klement (1960, pl.4, figs.10–11; text-figs.18–19) as type, which he cited separately (Brenner, 1988, p.35). Thus, Brenner (1988, p.65) effectively created a new genus, Meristaulax Brenner, 1988, which is validly published since Brenner (1988, p.65–66) provided a description under the single formal species Meristaulax granulata Brenner, listed a type and presented illustrations.
Type: Sarjeant, 1984a, pl.3, figs.3–4, text-fig.3, as Meristaulax granulata.