Nannotax3 - ntax_Farinacci

Original descriptions of taxa - also emended descriptions for a few taxa. For coccolithophores, and many calcispheres, these are pages from the Farinacci & Howe Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was originally compiled by Prof A. Farinacci 1969-1989, since 2000 it has been updated and extended by Richard Howe - see The Farinacci and Howe Catalog - an Introduction.
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Citation: Mauriceblackia Varol 2023

Type species: Ericsonia media Bown, 2016

Type repository: not stated, presumalby the author's collection

Diagnosis: Circular to elliptical placoliths constructed of a non- birefringent distal shield, birefringent proximal shield with an acute inclination angle, and a distally protruding tube cycle.

Description: Mauriceblackia is a circular to elliptical placolith with a non-birefringent distal shield and a double-layered proximal shield with an acute inclination angle (15–25◦) and a birefringent tube cycle. The spaced proximal shield has a similar diameter to the distal shield. The tube cycle with a serrated margin protrudes distally well above the distal shield. The segments at the serrated margin of the tube cycle are prominent and number between 30 and 46. The diameter of the broad tube cycle is much greater than the width of the shield. The narrow central opening may be present in some species. The tube cycle and the proximal shield create an asymmetrical X-shaped structure in side view.

In honour of renowned nannofossil specialist Professor Dr. Maurice Black, UK.

Optical properties: In cross-polarised light, Mauriceblackia displays laevogyre-inclined extinction lines on the distal side (Plate 2, Figs. 21–22) and dextrogyre-inclined extinction lines on the proximal side (Plate 2, Fig. 23–24). When using the gypsum plate, the blue interference pattern corresponds to the horizontal axis on the distal side (Plate 2, Fig. 22). In contrast, the blue interference pattern corresponds to the vertical axis on the proximal side (Plate 2, Fig. 24). The entire form is birefringent in side view.

Remarks: Mauriceblackia differs from Coccolithus and Senelia by having a tube cycle that protrudes above the distal shield and a proximal shield with an acute angle inclination. Mauriceblackia is further distinguished from Senelia by having a spaced proximal shield with acute-angled inclination (Plate 2, Figs. 14–1; 18–19), whilst Senelia has an appressed proximal shield (reduced and resides in the perimeter of distal shield). Mauriceblackia and Noelia have protruding tube cycles distally. Mauriceblackia differs from Noelia by having a spaced proximal shield with acute-angled inclination, whereas Noelia has an appressed proximal shield. Moreover, Mauriceblackia displays laevogyre extinction lines on the distal side, whereas Noelia displays dextrogyre extinction lines on the distal side.

References:

Varol, O. (2023). New Paleocene calcareous nannofossils: Carlamuelleria, Davidbukrya, Mauriceblackia, Noelia and Senelia. Marine Micropaleontology. 180: 1-41. gs

CATALOG - Mauriceblackia

References:

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