Acaenolithus undatus

Acaenolithus undatus Black, 1973

Acaenolithus vimineus Black, 1973

Species of Acaenolithus having a size between 5.5µm and 7.0µm is placed to Acaenolithus undatus. Originally, described by having one or two triangular expansions on either side of the central cross's long arms. This future is only visible in well-preserved specimens under SEM. Acaenolithus undatus can’t be consistently identified from Acaenolithus vimineus under the light microscope. The latter species has perpendicular meshes at right angles to the cross's arms and visible only in well-preserved specimens under SEM. Based on its size, Acaenolithus vimineus considered to be the junior synonym of Acaenolithus undatus.

Black, M., (1973): British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). PalaeontographicalSociety Monograph, 127: 49-112.