|Daughter taxa (time control age-window is: 0-800Ma)|
Like A. collactea but smaller (<0.2 mm), lower trochospiral, test; and with smaller, often indistinct aperture
Small (~0.25-0.30 mm), 5-chambered and compact (involute) test.
Compact, strongly muricate test with 5 globular, inflated chambers in last whorl.
Numerous (6-8; rarely 9-10) chambers in final whorl; large and widely open umbilicus
Test with 4-4½ chambers in the final whorl, planoconvex with scalloped, lobulate peripheral margin; distinctly muricate; chambers umbilically inflated
Test compact coiling; muricate surface texture; final chamber kummerform or bullate and/or with sutural bullae.
Like A. alticonica but higher-spired; chambers less closely appressed; and umbilicus broader.
High trochospiral test with closely appressed, angular chambers; strongly muricate
Test low trochospiral, moderately evolute; 4-5 rounded chambers elongated in the axis of coiling; final chamber often reduced in size; lobulate periphery; deep and relatively wide umbilicus; sutures on spiral side deep, chambers often overlapping; moderately to strongly muricate.
Chambers subtriangular to wedge-shaped (cuneiform) and lunate, terminal chambers often laterally angulate and peripherally disjunct; umbilicus widely open; densely muricate umbilical side but only weakly muricate spiral side.
Last whorl with strongly angular disposition of the chambers; outline strongly lobulate.
Like A. sibaiyaensis but with axially-compressed test, strongly lobulate peripheral margin, and chambers change ontogenetically from globular to more lenticular shapes.
Numerous (5-9) chambers in final whorl, and almost planispiral test
Like A. soldadoensis but with more (5-7 vs 4) of globular (vs tangentially elongate) chambers in final whorl; straighter, radial sutures on both sides of the (generally higher spired) test and a larger, deeper umbilicus.
Large; 4½-6 chambers in final whorl; moderate to low spired, final chamber often curving partly over the umbilicus; umbilical surface strongly muricate; peripheral margin rounded with chambers elongate parallel to the coiling axis and in the direction of coiling; umbilicus deep and large.
Test small, tightly coiled with strongly elevated spire; overall shape sub-sphaerical; umbilicus narro,w deep and surrounded by muricae; final chamber usually diminutive with an arched aperture.
Like A. boudreauxi but 4 (vs 4½-5) chambers in final whorl, and (sub)quadrate test with subangular periphery and weak to moderate murical concentration on the periphery.
Like A. boudreauxi but larger and with distinct punctate pseudocarina formed by peripheral concentration of blunt, thick muricae.
Test anguloconical, tightly coiled with 4½-5 compressed chambers in fine whorl; straight radial sutures on the umbilical side; no muricocarina.
Like A. topilensis but more evolute, with 5-6 chambers in final whorl, final chamber more disjunct; strongly muricate especially on the umbilical shoulders, and around the peripheral margin.
Chambers distinctly inflated, anguloconical; last 1 or 2 chambers strongly compressed, angulate and disjunct; rimmed by thick, blunt circum-cameral muricocarinae; sutural supplementary apertures on spiral side.
Test strongly muricate, subquadrate; last chamber disjunct, cuneate to mitriform lwith heavy circum-peripheral concentration of partially fused muricae.
Like A. pseudotopilensisbut with more compact test, which is densely muricate, and with more incised sutures.
Like A. pseudotopilensis but with angular test; chambers loosely disposed to each other at ~ 90°; and with a distinct, but discontinuous, peripheral muricocarina.
Like A. wilcoxensis but with triangular to wedge- or cuneate-shaped chambers in the final whorl, disjunct (separation of) chamber margins and more densely muricate wall.
Test (sub)quadrate, with 4-chambers in the final whorl, planoconvex, with subrounded to (later) subacute axial outline; distinctly muricate.
Test generally elongate-oval, with 4 chambers in the final whorl, narrow umbilicus; later chambers on spiral side tangentially longer than radially broad.
Like A. coalingensis but with triangular (broadly wedge-shaped) chambers and straight, incised, sutures on the umbilical side.
Test robust, compact, 3-4 chambers in final whorl; strongly and bluntly muricate; peripheral margin broadly rounded in edge view; chambers are arranged at right angles to each other are usually separated by deep, incised sutures on umbilical side, and increase rapidly in size.
Test compact, small, trochospiral, with 4 (rarely 5) rounded, tightly packed, radially compressd and axially elongate chambers; early whorls raised above surface of last whorl; moderately muricate, particularly on umbilical side.
Test nearly circular, 5-6 chambers in final whorl, weakly lobulate outline; axial periphery broadly rounded to subangular, chambers on umbilical side moderately convex, early whorls on spiral side elevated above later whorl(s); umbilicus usually broad and open exposing earlier whorls; entire test weakly muricate, aperture an interiomarginal, umbilical-extraumbilical slit.
Specimens which cannot be assigned to established species
1. Acarininids with angular chambers (e.g., A. crassaformis);
2. Acarininids with rounded chambers (e.g., A. acarinata);
3. Intermediate acarininids (e.g., A. conicotruncata).
Subsequent authors have questioned the inherent morphological homogeneity of this group by considering Acarinina to be a synonym for taxa as phylogenetically distinct as Turborotalia and Globorotalia. As conceived herein, Acarinina is characterized by rounded to subangular, unkeeled chambers that are covered with coarse pustules (muricae), which become dense, enlarged, and spike-like on the umbilical surface around the aperture. The heavy growth of pustules form deep funnel-shaped entrances to the pores and may also partially or completely close the pores. In Paleocene forms, the aperture has a very thin lip or none at all. [Olsson et al. 1999]
A particular issue of discussion within the Working Group has been the status of the genus Truncorotaloides. Blow (1979, p. 1033-1034) gave a comprehensive overview of the morpho- and phylogenetic trends which he viewed as definitive in delineating the genus Truncorotaloides and its differentiation from Acarinina. Primary among these was the development of “raised, imperforate (in the sense that normal mural-pores are absent), non-muricate narrow areas of test material usually around the distal (outer) margins of the sutural margins adjacent to the supplementary apertures”. These true supplementary apertures were considered functional in life for the extrusion of protoplasm in much the same manner as among the species of modern Globigerinoides. The dorsal/spiral apertures seen on Acarinina were considered as secondary openings (lacking raised imperforate rims) formed by late stage calcification over previously calcified strongly muricate edges leaving apparent “gaps” in the chamber junctions. Other important aspects of the Truncorotaloides stage of evolution included: lateral angulation of the chambers; in advanced (end) members strongly disjunct chambers that bear circumcameral muricocarinae.
Blow (1979, p. 1034) recognized three lineages in which these morphogenetic trends were said to have been iteratively produced:
1) Truncorotaloides quetra (evolved from Acarinina pseudotopilensis) in his Zone P7 (=Zone E4 of this
2). Truncorotaloides rohri s.l (supposedly evolved from Acarinina bullbrooki via the Acarinina pseudodubia-
piparoensis group in Zone E10/11);
3). Truncorotaloides topilensis (evolved from Acarinina praetopilensis in uppermost Zone E7).
While we agree with Blow (1979) on the potential significance of supplementary apertures as adaptive features, and agree that in principle they might be used to delimit genera (as in Neogene Globigerinoides) we cannot sustain his generic concept of Truncorotaloides because it is demonstrably polyphyletic on Blow’s original terms and also according to the modified phylogeny presented here. To recognize rohri in a monospecific Truncorotaloides would also compel us to name a new genus for quetra, which seems unnecessary. Similarly, Blow (1979) included various globular forms in his genus Muricoglobigerina that are not closely related according to our researches; hence his concept of that genus is not workable either.
With regard to the validity of the Family Truncorotaloididae Loeblich and Tappan, 1961, the International Code of Zoological Nomenclature, Chapter 8, Article 39 states that the family name is invalid only in cases of homonymy or if the type species is found to be invalid. In this case Article 40 applies: “When the name of a type genus of a nominal family-group taxon is considered to be a junior synonym of the name of another nominal genus, the family-group name is not to be replaced on that account alone”. The description of the family remains that of the Truncorotaloididae. [Berggren et al. 2006]
Catalog entries: Acarinina, Muricoglobigerina, Pseudogloboquadrina, Truncorotaloides
Distinguishing features: Moderate to low trochospire; chambers ovoid, usually 4-6 in final whorl.
Wall muricate with pustules on umbilical shoulders;
Most likely ancestor: Morozovella - at confidence level 0 (out of 5). Data source: Olsson et al. 1999.
Likely descendants: Morozovelloides; Pearsonites;
Last occurrence (top): at base of Aquitanian Stage (3% up, 23Ma, in Aquitanian stage). Data source: Total of range of species in this database
First occurrence (base): near top of Danian Stage (85% up, 62.3Ma, in Danian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 261
Berggren, W. A., Pearson, P. N., Huber, B. T. & Wade, B. S. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 9): 257-326. gs V O 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. 2: 1-1413. gs 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. gs Jenkins, D. G. (1966b). Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics. 8 (6): 1088-1126. gs Loeblich, A. R. & Tappan, H. (1961). Cretaceous planktonic foraminifera: Part I-Cenomanian. Micropaleontology. 7: 257-304. gs Martin, L. T. (1943). Eocene foraminifera from the type Lodo Formation, Fresno County, California. Stanford University Publications, Geological Sciences. 3(3): 1-35. gs Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. gs Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs
Berggren, W. A., Pearson, P. N., Huber, B. T. & Wade, B. S. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 9): 257-326. gs V O
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. 2: 1-1413. gs
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. gs
Jenkins, D. G. (1966b). Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics. 8 (6): 1088-1126. gs
Loeblich, A. R. & Tappan, H. (1961). Cretaceous planktonic foraminifera: Part I-Cenomanian. Micropaleontology. 7: 257-304. gs
Martin, L. T. (1943). Eocene foraminifera from the type Lodo Formation, Fresno County, California. Stanford University Publications, Geological Sciences. 3(3): 1-35. gs
Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. gs
Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs
Acarinina compiled by the pforams@mikrotax project team viewed: 19-4-2021
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