Acarinina cuneicamerata Blow 1979 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
Notice: This catalogue page may contain unedited data.
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Species Acarinina cuneicamerata Blow 1979 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Densely muricate, nonspinose,
normal perforate.
Test morphology: Low trochospiral, 5-6
moderately inflated, strongly muricate chambers in last
whorl; margins of later chambers in final whorl exhibit
tendency to develop angulate and disjunct chamber
separation in some individuals; sutures straight, radial,
depressed to moderately incised; umbilicus wide, deep,
relict apertures of ante- and penultimate chambers visible
within umbilical area and bordered by distinct,
circumumbilically extending apertural lip(s) connecting
to the relatively broad lip of the final chamber; no
circumumbilical concentration of muricae; aperture
umbilical-extraumbilical, extending towards, but not
reaching the periphery; spiral side weakly muricate,
about 12, flattened chambers arranged in relatively
involute spire of 2 whorls; minute, discrete openings
observable, at suture/chamber junctions on well
preserved specimens; sutures straight to weakly curved
and tangential to periphery; chambers of last whorl lunate
with ante- and penultimate chamber often wedge-shaped
(cuneiform); in edge view umbilical side is
anguloconical with rounded to subacute peripheral
margin; spiral side flat.
Size: Diameter of holotype 0.41 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
This form is distinguished by its combination of subtriangular to wedge-shaped (cuneiform) and lunate chambers, tendency to develop laterally angulate and peripherally
disjunct terminal chambers, widely open umbilicus, and densely muricate umbilical side and only weakly muricate spiral side.
DISCUSSION.-
This taxon was described by Blow (1979) for predominantly 5-6 chambered (in the final
whorl), loosely coiled, muricate forms that exhibit a
tendency to develop laterally angulate, disjunct terminal chambers and a relatively wide open umbilicus. He drew
attention to the potential confusion in distinguishing 6-
8 chambered forms from the stratigraphically coeval A.
aspensis but noted that the smoothly rounded chamber
margins (absence of lateral angularity) of aspensis serve
to distinguish it from cuneicamerata.
The FAD of A. cuneicamerata has recently been
calibrated to Chron C22r at -50.4 Ma by Hancock and
others (2002) at ODP Hole 762C, Exmouth Plateau,
north-west Australian margin at essentially the same
(estimated) level of the FAD of (the elusive)
Planorotalites palmerae which has been used to denote
the top of Zone P8 (=Zone E6 of this paper). Accordingly
the FAD of this taxon has been used to denote the base
of Zone E6 in the recently revised Eocene zonation
(Berggren and Pearson, 2005). The little known taxon
Globorotalia berwaliana Mohan and Soodan may be a
senior synonym.
PHYLOGENETIC RELATIONSHIPS.-
Probably
evolved from Acarinina angulosa and left no
descendants.
STRATIGRAPHIC RANGE.-
Zone E6 (base, by
definition) to Zone E9 (lower part) (Blow 1979; Hancock
and others, 2002).
GEOGRAPHIC DISTRIBUTION.-
Equatorial Atlantic Ocean, Tethyan region (Egypt) and Indian Ocean.
STABLE ISOTOPE PALEOBIOLOGY.-
Probably recorded by Boersma and others (1987) (as A. pentacamerata) with negative ò18O indicating a surface
water habitat. Pearson and others (2001) recorded it with the most negative ò18O of a large suite of middle Eocene species.
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| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Truncorotaloididae
Genus Acarinina
Species Acarinina cuneicamerata
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| Synonym list: |
Pearson et al. (2006):
? 1969 Globorotalia berwaliana Mohan & Soodan. - Mohan & Soodan : p. 9-10 pl. 1a-f [Middle Eocene Globigerinoides kugleri -
Globigerina frontosa Assemblage Zone, Benvali Stream,
Kutch, India]
p 1979 Globorotalia (Acarinina) cuneicamerata Blow. - Blow : p.924 pl. 146, fig. 6-8 [Zone P9, DSDP Site 47,
Shatsky Rise, north-west Pacific Ocean];
pl. 153, fig. 1-4 [Zone P9, KANE 9, piston core 42, Endeavour Seamount, equatorial Atlantic Ocean];
pl. 156, fig. l , 2 (holotype), 3-4;
pl. 203, fig. 5;
detail of pl. 146: fig. 5 (given erroneously as detail of pl. 156: fig. 6);
pl. 165: figs. 4 and 7 [Zone P10, KANE 9, piston core 42,95 cm; Endeavour Seamount, equatorial Atlantic Ocean]
1979 Globorotalia (Acarinina) sp. . - Blow : p.924 pl. 154; fig. 6, 7 (Globorotalia (Acarinina) sp. ex interc. G. (A.). decepta
(Martin) and G. (A.) cuneicamerata n.sp. Blow,
1979);
[Zone P10, KANE 9, piston
core 42,95 cm; Endeavour Seamount, equatorial Atlantic
Ocean].
2006 Acarinina cuneicamerata Blow. - Pearson et al. : p.281 pl. 9.9; fig. 1-16 (Pl. 9.9, Figs. 1-4, 8: reillustration of holotype and
paratypes of Globorotalia (Acarinina) cuneicamerata
Blow)
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| Specimen: |
Natural History Museum, London, Inventory number: BP 60/3
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| References: |
Mohan,M.. and Soodan,K.S.. (1969):
Two new Lutetian species of Rotaliina from Kutch . Journal of the Palaeontological Society of India Vol. 12 p. 9-11
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
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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