Acarinina rohri Brönnimann & Bermudez 1953 (TaxonConcept

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Species Acarinina rohri Brönnimann & Bermudez 1953

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

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]

1953 Truncorotaloides rohri var. guaracaraensis Brönnimann & Bermudez. - Brönnimann & Bermudez : p.819 pl. 87; fig. 1-3 [middle Eocene, Duff Road, central Trinidad]

1953 Truncorotaloides rohri var. piparoensis Brönnimann & Bermudez. - Brönnimann & Bermudez : p.819 pl. 87; fig. 4-6 [middle Eocene, Duff Road, central Trinidad]

1953 Truncorotaloides rohri var. mayoensis Brönnimann & Bermudez. - Brönnimann & Bermudez : p.820 pl. 87; fig. 10-12 [middle Eocene of 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]

1971 Truncorotaloides rohri Brönnimann & Bermudez. - Postuma : p.232 illustrations on p. 233 [Trinidad]

? 1972 Turborotalia (Acarinina) alteconica Samuel. - Samuel : p. 196-197 pl. 55; fig. 1-3 [Middle Eocene Globigerapsis index zone, Borehole Sr- l, Bakony Mountains, Hungary].

? 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)

Specimen:

Smithsonian Museum of Natural History, Washington, D.C., Inventory number: CC no. 172694

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

Anonymous: Unedited TaxonConcept data

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