IRMNG taxon details
current name source
Schrank, E. (2003). Small acritarchs from the Upper Cretaceous: taxonomy, biological affinities and palaeoecology. <em>Review of Palaeobotany and Palynology.</em> 123(3-4): 199-235., available online at https://doi.org/10.1016/s0034-6667(02)00228-2 [details]
habitat flag source
as per family (almost all marine) [details]
Unreviewed
Descriptive info Upper Cretaceous (Campanian); U.S.A. (Rio Blanco County, Colorado). (Index Nominum Genericorum) [details]
Taxonomic remark From Schrank, 2003: The genus Operculites was regarded as a junior synonym of Sigmopollis Hedlund (1965) by Srivastava (1984). Operculites is retained here for those species that are distinguished by a psilate to granulate wall and by the absence of a fully developed S-shaped aperture from typically spinose Sigmopollis grains. Operculites may also be regarded as a synonym of Leiosphaeridia Eisenack, 1958, a long-ranging (Precambrian to Cenozoic) and large genus (about 170 species listed in Fensome et al., 1990) that is notoriously difficult to classify because of its scarcity in relevant morphological features. However, the type species of Operculites, O. carbonis from the Campanian of Colorado, is easily distinguished from the type species of Leiosphaeridia, L. baltica Eisenack, 1958 from the Baltic Ordovician, by its smaller size (21-26 µm vs. 80-150 µm), its thinner wall (0.5-1 µm vs. 3-8 µm) and the possession of a round or helicoidal aperture. Considering these facts and the conclusion of Lindgren (1981) that different natural algal groups are included in the latter genus it seems justified to treat Operculites as a genus different from Leiosphaeridia. [details]
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