Nannotax3 - ntax_mesozoic - Gartnerago waszczakii

Distinguishing features:
Parent taxon (Gartnerago): Tiered coccoliths with distinctive LM images consisting of a narrow to moderately-broad rim with a narrow, dark outer-cycle; a diagnostic, bright median-cycle; and a dark, inner-cycle. Central-area structures variable but generally dark in LM.
This taxon: Central plate of 6 units; large (8-11 µm)

Citation: Gartnerago waszczakii Lees, Schueth & Howe in Schueth & Lees (2019)

Basionym: Gartnerago waszczakii Lees, Schueth & Howe in Schueth & Lees (2019)

A relatively large species of Gartnerago with a broad central-area filled by a plate that is divided into six crystallographically-distinct units. These units are divided by distinctively curved sutures. The centrally-positioned longitudinal suture has a sigmoidal shape, the straight portion extending for about half the length of the coccolith, with inflection points positioned at about one-quarter of the length away from the rim. The four remaining sutures are slightly curved and oriented with the short axis. One set of these shorter sutures extends from a point close to the center of the coccolith, curving in opposite directions to points at the rim that are offset either side of the short axis.The other set is subhorizontal, extending from the inflection point in the longitudinal suture to the rim. The two blocks defined by the latter suture and the sigmoidal part of the longitudinal suture have a higher birefringence, and are smaller than, the other four blocks. Diagonal pairs of the four larger blocks go into extinction together. On rotation, the sutures remain clearly visible. [Schueth & Lees 2019]
Differentiation: The new species is somewhat similar to G. clarusora, which has four blocks divided by two straight axial sutures, but is distinctive in being larger and having six blocks, divided by five curved sutures, with the polar blocks being relatively highly birefringent. [Schueth & Lees 2019]

Geological Range:
Last occurrence (top): within UC10 zone (86.50-89.77Ma, top in Coniacian stage). Data source: Schueth & Lees 2019
First occurrence (base): within UC8 zone (91.78-92.99Ma, base in Turonian stage). Data source: Schueth & Lees 2019

References:

Lees, J. A. & Schueth, J. (2020). Taxonomic note – New Upper Cretaceous nannofossil taxa from the Turonian of New Mexico, USA. Journal of Nannoplankton Research. 38(1): 81-82. gs V O

Schueth, J. D. & Lees, J. A. (2019). Pioneer nannofossil assemblages from the initial transgression of the Niobrara seaway in the Turonian, San Juan Basin, New Mexico, USA. Marine Micropaleontology. 151: x-y. gs

Gartnerago waszczakii

References:

Comments (0)

Add Comment