Nannotax3 - ntax_cenozoic - Lithostromation simplex

Citation: Lithostromation simplex (Klumpp, 1953) Bybell, 1975

Basionym: Trochoaster simplex Klumpp, 1953

Synonyms:

Discoaster bramlettei Martini 1958 [cf Martini 1971]
Polycladolithus stellaris Stradner 1959 [according to Martini & Stradner 1960, Stradner et al. 2010]
Trochoaster duplex Klumpp, 1953 [according to Bybell 1975]

NB This appears to be a rather morphologically plastic group, so broad species concepts are probably appropriate

Variants:

Trochoaster aubryae Varol 1989 - rays extend beyond central body and are slightly bent [my interpretation - JRY 2024]

NB L. martinii and L. nodosum are similar to T. aubryae and all three might be regarded as variants of L. simplex

Taxonomic discussion: A sub-species, T. simplex variabilis, was described in Martini (1991) - but we have not yet obtained a copy of this paper.

Distinguishing features:
Parent taxon (Lithostromation): Triangular to stellate nannoliths with porous structure formed from small crystallites. All show 3-fold symetry but with a wide range of forms.
This taxon: Hexagonal, perforate nannolith with low birefringence. Six thin rays extend a short distance beyond the margin of hexagonal disc with numerous pores. Secondary shorter rays are present between each of the longer rays, which terminate at the disc edge.

"This species has a hexagonal outline which thickens towards its center. The surface is pitted with circular perforations which are surrounded by knobby, hexagonal ridges. Each apex of the hexagon ends in a short ray. The planar hexagonal shape distinguishes L. simplex from other species in this genus." [Bybell 1975] "

See also: Imperiaster obscurus - forms with two triplets of rays in separate planes;

Geological Range:
Last occurrence (top): within Late Eocene Sub-Epoch (33.89-37.75Ma, top in Priabonian stage). Data source: Perch-Nielsen 1985
First occurrence (base): within Early Eocene Sub-Epoch (47.84-55.96Ma, base in Ypresian stage). Data source: Perch-Nielsen 1985

References:

Bown, P. R. & Dunkley Jones, T. (2006). New Paleogene calcareous nannofossil taxa from coastal Tanzania: Tanzania Drilling Project Sites 11 to 14. Journal of Nannoplankton Research. 28(1): 17-34. gs

Bybell, L. (1975). Middle Eocene calcareous nannofossils at Little Stave Creek, Alabama. Tulane Studies in Geology and Paleontology. 11(4): 177-247. gs O

Dunkley Jones, T., Bown, P. R. & Pearson, P. (2009). Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophycidae) from the Pande Formation (Kilwa Group), Tanzania. Journal of Systematic Palaeontology. 7(4): 359-411. gs

Martini, E. & Schiller, W. (1998). Calcareous nannoplankton from Sieblos/Rhoen and the Nieuwied Basin (Lower Oligocene). Geologisches Abhandlungen Hessen. 100: 165-172. gs

Martini, E. & Stradner, H. (1960). Nannotetraster, eine stratigraphisch bedeutsame neue Discoasteridengattung. Erdoel-Zeitschrift. 76(8): 266-270. gs

Martini, E. (1958). Discoasteriden und verwandte Formen im NW-deutschen Eozän (Coccolithophorida). 1. Taxonomische Untersuchungen. Senckenbergiana Lethaea. 39: 353-388. gs

Martini, E. (1971a). Die Typen und Typoide des Natur-Museums Senckenberg, 46): Fossiles Nannoplankton. Senckenbergiana Lethaea. 52: 115-127. gs

Martini, E. (1991). Endemische Vertreter der Gattung Trochoaster (kalkiges Nannoplankton) im westdeutschen Unter-Oligozän. Geologisches Jahrbuch. 128: 167-177. gs

Perch-Nielsen, K. (1971c). Elektronenmikroskopische untersuchungen an Coccolithen und verwandten Formen aus dem Eozan von Danemark. Biologiske Skrifter, Kongelige Danske Videnskabernes Selskab. 18(3): 1-76. gs O

Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 427-555. gs

Self-Trail, J. (2011). Paleogene Calcareous Nannofossils of the South Dover Bridge core, Southern Maryland (USA). Journal of Nannoplankton Research. 32(1): 1-28. gs

Stradner, H., Aubry, M. -P. & Bonnemaison, M. (2010). Calcareous nannofossil type specimens in the collection of the Geological Survey of Austria: A taxonomic and stratigraphic update. Jahrbuch der Geologischen Bundesanstalt. 150(1-2): 9-84. gs

Varol, O. (1989b). Eocene calcareous nannofossils from Sile (northwest Turkey). Revista Española de Micropaleontología. 21: 273-320. gs

Lithostromation simplex

References:

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