Acarinina rohri Brönnimann & Bermudez 1953 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 rohri Brönnimann & Bermudez 1953 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Densely muricate, normal
perforate, nonspinose.
Test morphology: Low trochospiral test with
about 12-13 chambers in an evolute spire, 5 (less
commonly 6) rounded to subangular chambers in last
whorl; final chamber usually wedge-shaped and with
disjunct separation from antepenultimate chamber;
sutures on umbilical side weakly curved, depressed;
umbilicus narrow and relatively deep; aperture an
umbilical-extraumbilical arch extending towards the
peripheral margin; hemispherical to wedge-shaped
chambers on spiral side separated by straight to weakly
recurved, depressed sutures; distinct, rimmed
supplementary apertures visible at the base of the
antepenultimate and final chambers, rarely visible
between earlier chambers in last whorl; subrounded to
truncate in edge view; chambers on both sides of test
strongly muricate.
Size: Maximum diameter of holotype 0.37 mm,
thickness 0.22 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Acarinina rohri is
distinguished by its strongly muricate test, particularly
the concentration of muricae on the umbilical shoulders,
and around the peripheral margin, the tendency to
develop disjunct separation of chambers in
stratigraphically younger forms and by the development
of raised imperforate rims surrounding supplementary
apertures on the later chambers on the spiral side.
DISCUSSION.-
The taxonomy of this morphotype is
extremely complex and controversial. Several forms/taxa
have been ascribed to, or differentiated from, this species
over the past five decades. Below we attempt to reduce
the complexity surrounding the rohri group to its most
essential details:
l. Brönnimann and Bermudez (1953) described
rohri and differentiated three further varieties
based on variation in chamber shape in the final
whorl: guaracaraensis (rounded), mayoensis
(angular) and piparoensis (subangular;
intermediate between the rounded
guaracaraensis and the central morphotype:
rohri). In all, 21 well preserved specimens of
guaracaraensis were recorded, 8 of rohri, 5 of
piparoensis and only 2 of mayoensis; no
discussion of stratigraphic extent of these
morphotypes was presented.
2. Blow (1979, p. 951-953 and 1036-1041)
differentiated the rohri complex into two
distinct, but phylogenetically related groups:
guaracaraensis and piparoensis were assigned
to Acarinina (lacking distinct rimmed dorsal true
supplementary apertures, degree of lateral
angulation of chambers, degree of development
of typical disjunct chambers and the
organization of circumcameral/circumperipheral
muriococarina typical of Truncorotaloides (as
typified by rohri); while rohri and mayoensis
(with the characters listed above) were placed
in Truncorotaloides. The taxon guaracaraensis
was placed in synonymy with Globigerinoides
(vel Acarinina) pseudodubia Bandy (1949).
3. Blow (1979, p. 952-955) presented the case for
derivation of rohri from Acarinina bullbrooki
by way of the evolution / transition from A.
pseudodubia to piparoensis: increased number
of chambers in final whorl (4 to 5), gradual
tendency to develop more laterally angulate and
disjunct chamber geometry in last one or two
chambers.
In Our view a much more likely ancestor for
rohri is Acarinina topilensis, with which it shares several
characters to the exclusion of A. bullbrooki, including
the sinistal coiling bias, more incised sutures,
supplementary apertures and heavily muricate test. We
have not differentiated from rohri the 'transitional'
morphotypes illustrated by Blow of pseudodubia and
piparoensis, preferring to illustrate the wide degree of
variation we ascribe to rohri and its morphologic endmember
mayoensis, which we include here in the
synonymy of rohri.
The essentially neglected and rarely recognized
taxon Globigerinoides pseudodubia Bandy may be a
senior synonym of Acarinina rohri (for a dissenting view
see Blow, 1979, p. 951 who considered it a senior
synonym of G. (A.) guaracaraensis). We include this
form provisionally as a questionable senior synonym of
A. rohri.
The taxon Turborotalia (Acarinina) alteconica
was described by Samuel (1972) as a high-spired variant
of rohri. Similarly Truncorotaloides haynesi of Samanta
seems to be a large, more openly coiled variant of rohri.
PHYLOGENETIC RELATIONSHIPS.-
Evolved from
Acarinina topilensis via intermediate/transitional
morphotypes ascribed to the pseudubia-piparoensis
group (Blow, 1979, p. 951-955).
STRATIGRAPHIC RANGE.-
Zone E 10 to Zone E1 3.
GEOGRAPHIC DISTRIBUTION.-
Widely distributed
in (sub)tropical areas, Caribbean, Spain, Aquitaine,
North Africa, Middle East, India.
STABLE ISOTOPE PALEOBIOL0GY.-
No data
available. |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Truncorotaloididae
Genus Acarinina
Species Acarinina rohri
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| Synonym list: |
Pearson et al. (2006):
? 1949 Globigerinoides pseudodubia Bandy. - Bandy : p.123 pl. 24; fig. La-c [middle Eocene, Tallahatta Frn., Little Stave Creek, Alabama]
1953 Truncorotaloides rohri Brönnimann & Bermudez. - Brönnimann & Bermudez : p. 818-819 pl. 87; fig. 7-9 [middle Eocene, central Trinidad]
1957 Truncorotaloides rohri Brönnimann & Bermudez. - Bolli et al. : p.42 pl. 10; fig. 5a-c [holotype reillustrated]
1961 Truncorotaloides rohri Brönnimann & Bermudez. - Bermudez : p.1352 pl. 17; fig. 3a-b (4 fig.) [middle Eocene Zone P12, Guayabal
Fm., Mexico]
1970 Truncorotaloides rohri Brönnimann & Bermudez. - Samanta : p.207 pl. 3; fig. 20-21 [middle Eocene Orbulinoides beckmanni Zone,
Discocyclina biofacies, Lakhpat, Cutch, western India]
1970 Truncorotaloides haynesi Samanta. - Samanta : p.205 pl. 3; fig. 24-25 [middle Eocene Orbulinoides beckmanni Zone, Lakhpat, India]
? 1979 Globorotalia (Acainina) pseudodubia Bandy. - Blow : p.951 pl. 171, fig. 4 [middle Eocene, Zone PI l, Kilwa area, Tanzania, East Africa];
pl 194, fig. 5 and 6 [middle Eocene, Zone P13, Kilwa area, Tanzania, East Africa]
1979 Truncorotaloides rohri Brönnimann & Bermudez. - Blow : p.1037 pl. 195, fig. 4-9;
pl. 196, fig. 1-5;
pl. 206, fig. 1-7;
pl. 231, fig. 1,2 (same as pl. 195, fig. 4),
fig. 4 (same as pl. 195, fig. 9) [middle Eocene Zone P13,
Kilwa area, Tanzania, East Africa]
1979 Globorotalia (Acarinina) pseudodubia piparoensis Brönnimann & Bermudez. - Blow : p.953 pl. 171, fig. 5 and 6 [middle Eocene, Zone Pll, Kilwa area, Tanzania, East Africa];
pl 194, fig. 7-9;
pl. 195, fig. 2 [middle Eocene, Zone P13, Kilwa area, Tanzania, East Africa];
pl. 231, fig. 5 and 6 (details of pl. 194, fig. 8
and 7, respectively);
pl. 232, fig. 3-6 (details of pl. 194, fig. 9)
1979 Truncorotaloides rohri var. mayoensis Brönnimann & Bermudez. - Blow : p.1040 pl. 196, fig. 6-9 [middle
Eocene Zone P13, Kilwa area, Tanzania];
pl. 50, fig. 7, 8
(from Blow, 1969: 372-373, pl. 50; figs. 7,8 reillustrated) (same sample)
2006 Acarinina rohri Brönnimann & Bermudez. - Pearson et al. : p.311 pl. 9.20; fig. 1-16 (Pl. 9.20, Figs. 1-3: new SEMs of holotype of
Truncorotaloides rohri Brönnimann and Bermudez)
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| Specimen: |
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: CC no. 172694
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| References: |
Bandy,O.L. (1949):
Eocene and Oligocene foraminifera from Little Stave Creek, Clarke County, Alabama . Bulletins of American paleontology Vol. 32 p. 1-211
Brönnimann,P. and Bermudez,P.J. (1953):
Truncorotaloides, a new foraminiferal genus from the Eocene of Trinidad, B.W.I . Journal of Paleontology Vol. 27(6) p. 817-820
Bolli,H.M.; Loeblich,A.R. and Tappan,H. (1957):
The Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae, and Globotruncanidae . U.S. National Museum Bull. Vol. 215 p. 3-50
Bermudez,P.J. (1961):
Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleocene-Reciente).
In: Boletino Geologia (Venezuela), Special Publicacion Vol. 3
Samanta,B.K. (1970):
Middle Eocene Planktonic Foraminifera from Lakhpat, Cutch, Western India . Micropaleontology Vol. 16
Postuma,J.A. (1971):
Manual of Planktonic Foraminifera. p. 422 pp
Samuel,O.. (1972):
New species of planktonic foraminifers from the Paleogene of the west Carpathian in Slovakia (Czechoslovakia) . Zbornik Geologick"ck Vied Západné Karpaty Vol. 17 p. 165-221
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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