Aktasia trabeculatus
Set number: 2801
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1
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9
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10
10µm
Set number: 2800
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6
10µm
Set number: 2799
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7
10µm
Set number: 2298
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4
10µm
Set number: 2802
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10µm
Discolithus trabeculatus Górka, 1957
Eiffellithus trabeculatus (Górka, 1957) Reinhardt & Górka,1967
Helicolithus trabeculatus (Górka, 1957) Verbeek, 1977
Small species of Aktasia (< 6.0 µm) have a zeugoid outer wall and a protolith inner wall composed of eight large sub-quadrilateral segments. The central area contains a symmetrical diagonal cross whose arms are composed of parallel longitudinal segments arranged in two halves and lacking a distal process.
Aktasia trabeculatus is identified from Aktasia disgregatus by being smaller than 6.0 µm.
Aktasia trabeculatus differs from Aktasia compacta by having a symmetrical cross, whereas the latter has an asymmetrical cross.
Bukry, D. 1969. Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles 51 (Protista 2): 1-79.
Górka, H. 1957. Les Coccolithophoridés du Maestrichtien supérieur de Pologne. Acta Palaeontologica Polonica. 2: 239-284
Reinhardt, P. & Górka, H. 1967. Revision of some Upper Cretaceous Coccoliths from Poland and Germany. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 129(3): 240-256.
Stover, L. E. 1966. Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology 12(2): 133-167.
Verbeek, J.W. 1977. Calcareous nannoplankton biostratigraphy of Middle and Upper Cretaceous deposits in Tunisia, southern Spain and France. Utrecht Micropaleontological Bulletins, 16: 1-157.