Cretaceous microporid cheilostome bryozoans from the Campanian historical stratotype of southwest France

The Campanian of southwest France hosts rich and diverse bryozoan assemblages of global importance in tracing the faunal turnover from cyclostome to cheilostome dominance. Nevertheless, bryozoans from this historical stratotype region for the Campanian stage have been poorly studied, and most of the species erected by Alcide d’Orbigny in the 1850s remain unrevised. Here we focus on the four species of anascan-grade cheilostomes with opesiulate cryptocystal frontal walls, conventionally classified in the family Microporidae. One new genus and two new species are introduced: Platelinella solea n. gen. et n. sp. and Micropora mikesmithi n. sp. The enigmatic genus Dimorphomicropora Ducasse & Vigneaux, 1960 and the two species (D. voigti Ducasse & Vigneaux, 1960 and D. crestulata (Ducasse, 1958)) from southwest France are revised. Mandibulate polymorphs present in D. voigti resemble the B-zooids of Steginoporella but are unlikely to be homologous.