Taxonomic discussion: Favusellawashitensis 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]
holotype: G. washitensis
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] Morphology: Wall type: Size:
sp chamber shape:
umb chbr shape:
periph margin shape:
umbilical or test sutures:
N.B. These characters are used for advanced search. N/A - not applicable
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]
Plot of range and occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes