Acarinina rohri


Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Acarinina -> Acarinina rohri
Sister taxa: << < A. echinata, A. esnaensis, A. esnehensis, A. interposita, A. mcgowrani, A. mckannai, A. medizzai, A. nitida, A. pentacamerata, A. praetopilensis, A. primitiva, A. pseudosubsphaerica, A. pseudotopilensis, A. punctocarinata, A. quetra, A. rohri, A. sibaiyaensis, A. soldadoensis, A. strabocella, A. subsphaerica, A. topilensis, A. wilcoxensis,

Taxonomy

Citation: Acarinina rohri (Bronnimann & Bermudez 1953)
Rank: Species
Basionym: Truncorotaloides rohri
Synonyms:
Taxonomic 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:
1. Bronnimann and Bermúdez (1953) described rohri and differentiated three further varieties based on variation in chamber shape in the final perforate, nonspinose. 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 end- member 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. [Berggren et al. 2006]

Catalog entries: Globigerinoides pseudodubia;
Truncorotaloides haynesi;
Truncorotaloides rohri;
Truncorotaloides rohri guaracaraensis;
Truncorotaloides rohri mayoensis;
Truncorotaloides rohri piparoensis;
Turborotalia (Acarinina) alteconica;

Type images:

Short diagnosis: 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.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: 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. [Berggren et al. 2006]

Wall type: Densely muricate, normal perforate, nonspinose. [Berggren et al. 2006]

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. [Berggren et al. 2006]

Size: Maximum diameter of holotype 0.37 mm, thickness 0.22 mm. [Berggren et al. 2006]

Character matrix

test outline:Subcircularcoiling axis:Lowchamber arrangement:Trochospiralumbilicus:Narrow
edge view:Planoconvexumbilical or test sutures:Moderately depressedspiral sutures:Moderately depressedshell porosity:Finely Perforate: 1-2.5
wall texture:Coarsely muricateaperture:Umb.-extraumbilicalaperture border:N/Aaccessory apertures:Sutural
periphery:N/Aumb chamber shape:Inflatedsp chbr shape:Inflatedperiph margin shape:Moderately rounded
umb depth:Deepdiameter mm:0.37width mm:breadth mm:0.22
final-whorl chambers:5.0-6.0

Biogeography and Palaeobiology


Geographic distribution: Widely distributed in (sub)tropical areas, Caribbean, Spain, Aquitaine, North Africa, Middle East, India. [Berggren et al. 2006]
Aze et al. 2011 summary: Low latitudes; based on Berggren et al. (2006b)

Isotope paleobiology: No data available. [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): this study

Phylogenetic relations: Evolved from Acarinina topilensis via intermediate/transitional morphotypes ascribed to the pseudubia -piparoensis group (Blow, 1979, p. 951-955). [Berggren et al. 2006]

Biostratigraphic distribution

Geological Range:
Notes: Zone E10 to Zone E13. [Berggren et al. 2006]
Last occurrence (top): within E13 zone (37.99-39.97Ma, top in Bartonian stage). Data source: Eocene Atlas
First occurrence (base): within E10 zone (41.89-43.23Ma, base in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Berggren et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 9, p. 312

References:

Bandy, O.L., (1949). Eocene and Oligocene foraminifera from Little Stave Creek, Clarke County, Alabama. Bulletin of American Paleontology, 32(131): 1-210.

Berggren, W.A.; Pearson, P.N.; Huber, B.T. & Wade, B.S., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Allen Press, Lawrence, Kansas, pp. 257-326.

Bermudez 1953 [sorry, not in our bibliography yet]

Bermudez, P.J., (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Mem. III Congreso Geol. Venez. Editorial Sucre, Caracas, 1119-1393 pp.

Blow, W.H., (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In: Bronnimann, P. and Renz, H.H. (Editors), Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967, Leiden, Netherlands, pp. 380-381.

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden, 1413 pp.

Brönnimann, P. & Bermudez, P.J., (1953). Truncorotaloides, a new foraminiferal genus from the Eocene of Trinidad, B.W.I. Journal of Paleontology, 27: 817-820.

Loeblich, A.R., Jr. & Tappan, H., (1957). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 173-198.

Samuel, O., (1972). Planktonic Foraminifera from the Eocene in the Bakony mountains (Hungary). Zbornik Geologickych Vied Zapadne Karpaty, 17: 165-206.


Acarinina rohri compiled by the pforams@mikrotax project team viewed: 30-5-2017

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