pforams@mikrotax - Acarinina pseudosubsphaerica

Citation: Acarinina pseudosubsphaerica Pearson & Berggren 2006

Basionym: Acarinina pseudosubsphaerica

Synonyms:

Muricoglobigerina esnehensis (Nakkady).—Pearson and others, 1993: pl. 1: fig. 20 [middle Eocene Zone P11-P12, DSDP Site 523, Walvis Ridge, South Atlantic Ocean]. [Not Nakkady, 1950.]
Acarinina aquiensis (Loeblich and Tappan).—Lu and Keller, 1995: pl. 2: figs. 24-26 [Lower Eocene Zone P9, DSDP Site 577, Shatsky Rise, north-west Pacific Ocean]. [Not Loeblich and Tappan, 1957.]
Acarinina cf. subsphaerica (Subbotina).—Pearson and others, 2004:37, pl. 2, fig. 4 [middle Eocene, Zone P11, Tanzania Drilling Project Site 2, Kilwa Masoko, Tanzania]. [Not Subbotina, 1947.]

Taxonomic discussion: Despite being a relatively common form in the lower and middle Eocene, Acarinina pseudosubsphaerica n. sp. has not been formally recorded. Acarinina alticonica Fleisher is closely related and the two species have been observed to intergrade in Zone E6/E7 (undifferentiated) of Tanzania Drilling Project Site 2 (P .N. Pearson, unpublished data). Lu and Keller (1995) recorded a first occurrence in Zone P9 (=E7) of Acarinina aquiensis in DSDP Site 577 (Shatsky Rise, north-west Pacific Ocean), which is regarded as conspecific here, and not referable to Loeblich and Tappan’s species (which is a Paleocene form from the Aquia Formation of Virginia and Maryland probably related to/conspecific with Acarinina subsphaerica; see Berggren and Norris, 1997). [Berggren et al. 2006]

Distinguishing features: Like A. alticonica but higher-spired; chambers less closely appressed; and umbilicus broader.

Description

Wall type: Weakly muricate, cancellate on spiral side with large, bladed muricae on umbilical side, normal perforate, nonspinose.[Berggren et al. 2006]

Morphology: Compact subspherical test coiled in a high trochospire of about two whorls with circular, slightly lobate outline; 4-6 moderately inflated, radially compressed chambers in final whorl; dorsal sutures wide and depressed, between circular chambers; primary aperture slit-like or a low, broad arch, situated in a wide, open umbilicus, and often covered by a small, sparsely muricate final chamber.[Berggren et al. 2006]

Size: Maximum diameter of holotype 0.19 mm, thickness 0.16 mm.[Berggren et al. 2006]

Biogeography and Palaeobiology

Geographic distribution: Probably widely distributed in tropical and mid-latitude sites. [Berggren et al. 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Berggren et al. (2006b)

Isotope paleobiology: Recorded (under the name Muricoglobigerina esnehensis) as a mixed layer dwelling species by Pearson and others, (1993). [Berggren et al. 2006]
Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy δ¹³C and relatively light δ¹⁸O. Sources cited by Aze et al. 2011 (appendix S3): Pearson et al. (1993)

Phylogenetic relations: Descended from A. alticonica. [Berggren et al. 2006]

Most likely ancestor: Acarinina alticonica - at confidence level 4 (out of 5). Data source: Berggren et al. (2006) fig9.2.
Likely descendants: Acarinina echinata;

Biostratigraphic distribution

Geological Range:
Notes: Zone E7 to Zone E10 [Berggren et al. 2006]
Last occurrence (top): within E10 zone (41.89-43.23Ma, top in Lutetian stage). Data source: Eocene Atlas
First occurrence (base): within E7a subzone (48.31-50.20Ma, base in Ypresian stage). Data source: Eocene Atlas

Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 303

References:

Berggren, W. A. & Norris, R. D. (1997). Biostratigraphy, phylogeny and systematics of Paleocene trochospiral planktonic foraminifera. Micropaleontology. 43(supplement 1): 1-116. gs

Berggren, W. A., Pearson, P. N., Huber, B. T. & Wade, B. S. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 9): 257-326. gs V O

Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 173-198. gs V O

Lu, G. & Keller, G. (1995). Planktic foraminiferal faunal turnovers in the subtropical Pacific during the Late Paleocene to Early Eocene. Journal of Foraminiferal Research. 25: 97-116. gs

Nakkady, S. E. (1950). A new foraminiferal fauna from the Esna shales and Upper Cretaceous chalk of Egypt. Journal of Paleontology. 24(6): 675-692. gs

Pearson, P. N. & Berggren, W. A. (2006). Taxonomy, biostratigraphy, and phylogeny of Morozovelloides n. gen. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 10): 327-342. gs V O

Pearson, P. N., Shackleton, N. J. & Hall, M. A. (1993). Stable isotope paleoecology of middle Eocene planktonic foraminifera and multi-species isotope stratigraphy, DSDP Site 523, South Atlantic. Journal of Foraminiferal Research. 23: 123-140. gs

test outline:	Subcircular	chamber arrangement:	Trochospiral	edge view:	Equally biconvex	aperture:	Umbilical
sp chamber shape:	Globular	coiling axis:	Moderate-high	periphery:	N/A	aperture border:	N/A
umb chbr shape:	Subtriangular	umbilicus:	Wide	periph margin shape:	Broadly rounded	accessory apertures:	None
spiral sutures:	Weakly depressed	umb depth:	Deep	wall texture:	Coarsely muricate	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Weakly depressed	final-whorl chambers:	4.0-6.0	N.B. These characters are used for advanced search. N/A - not applicable

Acarinina pseudosubsphaerica

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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