Upper cretaceous Meridionally costellate Hedbergellids: The genus Meridionalla El-Nakhal, 1982 vs. The genus Costellagerina petters, El-Nakhal and Cifelli, 1983

The two genera, Meridionalla El-Nakhal, 1982 and Costellagerina Petters, El-Nakhal and Cifelli, 1983, both erected to accommodate all the pre-Campanian meridionally costellate species, are discussed after comparison with the holotypes of the type species. Observations clearly indicate that Costellagerina is the appropriate genus, while the genus Meridionalla is inappropriate because its type species, Hedbergella murphyi Marianos and Zingula 1966 does not possess the textural ornamentation diagnostic for the genus.