Acarinina pseudosubsphaerica Pearson & Berggren 2006 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
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Species Acarinina pseudosubsphaerica Pearson & Berggren 2006 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Weakly muricate, cancellate on
spiral side with large, bladed muricae on umbilical side,
normal perforate, nonspinose.
Test 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.
Size: Maximum diameter of holotype 0.19 mm,
thickness 0.16 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
ETYMOLOGY.-
Named for its resemblance to the
Paleocene species Acarinina subsphaerica Subbotina.
DISTINGUISHING FEATURES.-
Acarinina pseudosubsphaerica
n. sp. is distinguished from all other middle
Eocene acarininids by its high spire, small size and
subspherical shape. It is similar in morphology to the
Paleocene species, A. subsphaerica (Subbotina), but
differs from that form and A. alticonica Fleisher by
having less closely appressed chambers and a broader
umbilicus.
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Project Site 2 (P.N. Pearson, unpublished data).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, 1 997).
PHYLOGENETIC RELATIONSHIPS.-
Descended
from A. alticonica.
STRATIGRAPHIC DISTRIBUTION.-
Zone E7 to
Zone E10
GEOGRAPHIC DISTRIBUTION.-
Probably widely
distributed in tropical and mid-latitude sites.
STABLE ISOTOPE PALEOBIOL0GY.-
Recorded
(under the name Muricoglobigerina esnehensis) as a
mixed layer dwelling species by Pearson and others,
(1993). |
| Systematics: |
35 Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Truncorotaloididae
Genus Acarinina
Species Acarinina pseudosubsphaerica
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| Synonym list: |
Pearson et al. (2006):
1993 Muricoglobigerina esnehensis Nakkady. - Pearson et al. : pl. 1; fig. 20 [middle Eocene Zone P 11 -P12,
DSDP Site 523, Walvis Ridge, South Atlantic Ocean]; [Not
Nakkady, 1950]
1995 Acarinina aquiensis Loeblich & Tappan. - Lu & Keller : pl. 2; fig. 24-26 [Lower Eocene Zone P9, DSDP Site 577, Shatsky Rise, north-west Pacific Ocean];
[Not Loeblich and Tappan, 1957]
2004 Acarinina cf. subsphaerica Subbotina. - Pearson et al. : p.37 pl. 2; fig. 4 [middle Eocene, Zone P1 l , Tanzania
Drilling Project Site 2, Kilwa Masoko, Tanzania];
[Not
Subbotina, 1947]
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| Specimen: |
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 523427
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 523427a
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 523427b
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 523427c
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| References: |
Pearson,P.N.; Shackleton,N.J. and Hall,M.A. (1993): The Stable Isotope Paleoecology of Middle Eocene Planktonic Foraminifera and Multi-species integrated Isotope Stratigraphy . Journal of Foraminiferal Research Vol. 23 p. 123-140
Lu,G. and Keller,G. (1995): Planktic Foraminiferal Faunal Turnovers in the Subtropical Pacific during the Late Paleocene to Early Eocene . Journal of Foraminiferal Research Vol. 25 p. 97-116
Pearson,P.N.; Nicholas,C.J..; Singano,J.M..; Bown,P.R..; Coxali,H.K..; van Dongen,B.E..; Huber,B.T.; Karega,A..; Lees,J.A..; Misaky,E..; Pancost,R.D..; Pearson,M.. and Roberts,A.P.. (2004): Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1-5 . Journal of African Earth Sciences Vol. 39 p. 25-62
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513
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