Shell architectures of the larger foraminiferal genera Cuvillierinella, Cyclopseudedomia, and Rhapydionina were studied by comparing topotypes of previously described species with new specimens retrieved from Late Cretaceous shallow-water carbonates of Pylos (Peloponnese, Greece), where the three genera are found in association. The megalospheric generation of each genus exhibits a distinctive shell shape in adult specimens (i.e., fan-shaped in Cyclopseudedomia, conical in Rhapydionina, and cylindrical in Cuvillierinella). Although their microspheric adults are similarly thin, flat, and discoidal, they can be identified at the genus level by means of a detailed structural analysis. Cuvillierinella shows the septula to be interrupted by a large preseptal space, while Cyclopseudedomia and Rhapydionina exhibit continuous, non-interrupted septula. In addition, Cyclopseudedomia presents only one row of medullar chamberlets, whereas Rhapydionina shows numerous medullar chamberlets distributed in a thick basal layer. Two new species, Cuvillierinella pylosensis and Rhapydionina fleuryi, are described. The former is a more complex taxon than the type species, C. salentina, while the latter corresponds to a more primitive species, R. lihurnica. Strontium-isotope stratigraphy indicates an uppermost Campanian- lowermost Maastrichtian age for these new species.
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|Titolo:||The late cretaceous genera cuvillierinella, cyclopseudedomia, and rhapydionina (rhapydioninidae, foraminiferida) in shallow-water carbonates of pylos (Peloponnese, Greece)|
FRIJIA, Gianluca (Secondo)
|Data di pubblicazione:||2011|
|Appare nelle tipologie:||03.1 Articolo su rivista|