Nannotax3 - ntax_non_cocco - Scrippsiella triquetracapitata

Scrippsiella triquetracapitata


Classification: ntax_non_cocco -> Dinophytes -> Thoracosphaeraceae -> Tangential wall -> Scrippsiella -> Scrippsiella triquetracapitata
Sister taxa: S. crystallina, S. lachrymosa, S. minima, S. patagonica, S. precaria, S. rotunda, S. sweeneyae, S. trifida, S. triquetracapitata, S. acuminata, S. regalis, S. fragments, S. sp.

Taxonomy:

Citation: Scrippsiella triquetracapitata Meier, Janofske, & Willems 2002
Rank: species

Catalog entries: Scrippsiella triquetracapitata

Original description: Diagnosis: Cysts are ellipsoid and formed by a single calcareous layer. The wall consists of subtriangular crystal units, from each of which a short triangular pyramidal spine emerges that ends in an isosceles triangular, pyramidal tip. The crystallographic c-axis of the crystals is oriented tangentially to the cyst wall.

Description: Scrippsiella triquetracapitata is a relatively large cyst with a length of 30–43.5 µm and a width of 21–38.8 µm (n = 5). The wall consists of a single layer of crystals with a thickness of about 2 µm. The main morphological feature of this species is its crystal form, showing a subisosceles triangular outline (Fig. 9, a–e). From each basal plate, which has a width of about 5 µm, a short pyramidal spine arises (about 2.5 µm long), which is tipped distally by an isosceles triangular pyramid. The edges of the triangles and pyramids are always rounded and the sides can be slightly concave, giving the units a triradiate character (Fig. 9b). An undamaged archeopyle has not been observed, but generally the operculum seems to include apical and intercalary plates (Fig. 9e). Cysts can be easily identified in LM studies by their triangular capitate spines, each of which appears in a monochrome color in polarized light using a gypsum plate. In thin sections the spines appear as monocrystalline units with their c-axis oriented tangentially to the cyst wall (Fig. 8).

Type images:


Morphology:

Wall structure: tangential
Archeopyle: ?Mesoepicystal (Streng et al. 2004)

Size:

Geological Range:
Last occurrence (top): Extant. Data source:
First occurrence (base): within no known fossil record (-Ma, base in "Holocene" stage). Data source:

References:

Meier, K. J. S., Janofske, D. & Willems, H. (2002). New calcareous dinoflagellates (Calciodinelloideae) from the Mediterranean Sea. Journal of Phycology. 38: 602-615. gs

Zonneveld, K. A. F., Meier, K. J. S., Esper, O., Siggelkow, D., Wendler, I. & Willems, H. (2005). The (palaeo-) environmental significance of modern calcareous dinoflagellate cysts: a review. Paläontologische Zeitschrift. 79(1): 61-77. gs


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Scrippsiella triquetracapitata compiled by Jeremy R. Young viewed: 7-10-2022

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