Distinguishing features: Parent taxon (Protentella): Like Globigerinella but adult chambers radially elongate. (Late Miocene - Pliocene) This taxon: Low trochospire; aperture extending from umbilicus to periphery but not onto spiral side, lip.
NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They are being edited as the site is developed and comments on them are especially welcome.
Description
Morphology: Test small, outline deeply lobulate, coiled in low trochospire; spiral side evolute, umbilical side involute with moderately shallow umbilicus. The spire is mostly level or depressed below spiral surface of final whorl of chambers (pI. 55 , fig. 7), giving false impression of biumbilicate, planispiral test; large specimens consist of nearly two whorls containing nine or more chambers with 5 (or rarely 6) in final whorl; early chambers spherical to subspherical, with later chambers progressively more radially elon-gate ; sutures essentially radial, slightly curved , and depressed; wall penetrated by closely spaced pores and surface roughened by cancellate ridges between pores and by irregular calcite growths on ridges (PI. 55, Fig. 2); aperture simple, extending from the umbilicus to the periphery along base of final chamber, showing individual variation in height, and bordered by distinct, uniform, perforate lip throughout length; aperture does not extend across the periphery onto dorsal side. Wall type:
K_S 1983 55-2.JPG
Character matrix
test outline:
Stellate
chamber arrangement:
Planispiral
edge view:
Equally biconvex
aperture:
Extraumbilical-peripheral
sp chamber shape:
Elongate
coiling axis:
Very low
periphery:
N/A
aperture border:
Thick lip
umb chbr shape:
Elongate
umbilicus:
Wide
periph margin shape:
Moderately rounded
accessory apertures:
None
spiral sutures:
Weakly depressed
umb depth:
Shallow
wall texture:
Cancellate
shell porosity:
Macroperforate: >2.5µm
umbilical or test sutures:
Strongly depressed
final-whorl chambers:
5-6
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionTropical Tropical (Kennett & Srinivasan 1983) Phylogenetic relationsCl. bermudezi (Bolli) (PI. 54, Figs. 6-8) is most closely related to Cl. nicobarensis but differs in swollen extremities of later chambers, which are much more separated at their attenuated proximal ends. Also the wall surface of Cl. bermudezi (Bolli) is distinctly pitted. The former species also has similar depressed trochoid coiling and shallow umbilical depression and a comparably placed but more elevated aperture. It appears to be the direct ancestor of Cl. nicobarensis. Protentella prolixa Lipps differs in being planispiral and in having an equatorial symmetrical aperture.
Most likely ancestor:Protentella prolixa - at confidence level 2 (out of 5). Data source: Aze et al. 2011. This is in disagreement with Kennett & Srinivasan (1983, fig 24) who inferred derivation from Clavatorella bermudezii, but that involved a long range gap..
Biostratigraphic distribution
Geological Range: Last occurrence (top): within N19 zone (4.37-5.20Ma, top in Zanclean stage). Data source: Kennett & Srinivasan 1983 First occurrence (base): within N16 zone (8.58-9.83Ma, base in Tortonian stage). Data source: Kennett & Srinivasan 1983
Plot of 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
(NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Protentella
Primary source for this page: Kennett & Srinivasan 1983, p.220
References:
Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs
Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs
Srinivasan, M. S. & Kennett, J. P. (1974a). A planktonic foraminifer (Clavatorella) from the Pliocene. Journal of Foraminiferal Research. 4(2): 77-79. gs
Protentella nicobarensis compiled by the pforams@mikrotax project teamviewed: 11-9-2024