pforams@mikrotax - Favusella washitensis

Citation: Favusella washitensis (Carsey, 1926)

Basionym: Globigerina washitensis Carsey, 1926

Synonyms:

Favusella confusa;
Favusella hedbergellaeformis;
Hedbergella hiltermanni;
Favusella nitida;
Favusella orbiculata;
Favusella papagayosensis;
Favusella pessagnoi;
Favusella planata;
Favusella quadrata;
Favusella scitula;
Ascoliella scotiensis;
Favusella stiftia;
Favusella voloshinae;
Hedbergella washitensis (Carsey, 1926)
Favusella wenoensis

Taxonomic discussion: Favusella washitensis is regarded as a species comprising several morphotypes of common origin. The different morphotypes represent different polymorphic stages in the life cycle and ecophenotypes of a single taxon.
Specimens attributed to Favusella are distinguised from Hedbergella by having a distinctly trochoid chamber shape, thicker and distinctly ornamented wall, characteristic pore distribution pattern, and umbilical position of the aperture. [copied from Chronos database]

Original description: Shell calcareous, usually white; surface very coarsely and regularly pitted; chambers well inflated, rapidly enlarging, arranged subspirally, dorsal side shows two or more whorls; ventral side shows only one whorl which consists of the last three or four chambers rather loosely joined about a depressed center; aperture at the inner margin of the final chamber.

Emended description: Emended (E.A.M. Koutsoukos, 2005): Test a low to relatively high trochospiral coil, equatorial periphery lobate, peripheral edge rounded. Chambers spherical to subspherical; 1.5 to 3.5 whorls each with 3 to 6 chambers, usually 4 to 5 in last whorl. Last chamber in mature individuals is usually smaller (embryonic), bare or with smooth ornamentation, extending over the umbilicus and partially covering it. Primary aperture usually arcuate, low to moderate, interiomarginal, umbilical to umbilical-extraumbilical in position, bordered by wide or narrow lip. Umbilicus shallow, of variable width. Sutures radial to slightly curved, depressed. Test surface covered by variable sculptural ornamentation, progressively developing from fine rounded tubercles and well-defined rounded or elongated tubercles (some forming elongated quadrangles = ridges), to reticulate system of fine to coarse ridges forming irregular polygonal cells (honeycomb pattern) in ephebic (adult) stage. Numerous minute pores located nearly exclusively within polygonal cells and between tubercles; pores scattered on edges of cell-ridges and tubercles. Size (maximum diameter) <0.1-0.25mm in the neanic stage (1 to 2 whorls), 0.25-0.35mm in ephebic forms (2.5 to 3 whorls) and 0.35->0.5mm in gerontic specimens (3 to 3.5 whorls). [copied from Chronos database]

Geological Range:
Last occurrence (top): within T. globotruncanoides zone (96.08-100.50Ma, top in Cenomanian stage). Data source: [copied from Chronos database]
First occurrence (base): within T. bejaouaensis zone (113.26-118.02Ma, base in Aptian stage). Data source: [copied from Chronos database]

References:

Carsey, D. O. (1926). Foraminifera of the Cretaceous of central Texas. University of Texas Bulletin. 2612: 1-56. gs

Pessagno, E. A. (1967). Upper Cretaceous planktonic foraminifera from the western Gulf Coastal Plain. Palaeontographica Americana. 5: 245-445. gs V O

Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs

test outline:	Lobate	chamber arrangement:	Trochospiral	edge view:	Spiroconvex	aperture:	Umbilical
sp chamber shape:	Inflated	coiling axis:	Moderate-high	periphery:	N/A	aperture border:	Thin lip
umb chbr shape:	Inflated	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	None
spiral sutures:	Moderately depressed	umb depth:	Shallow	wall texture:	-	shell porosity:	Microperforate: <1µm
umbilical or test sutures:	Moderately depressed	final-whorl chambers:	4.0-6.0	N.B. These characters are used for advanced search. N/A - not applicable

Favusella washitensis

References:

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