Acarinina praetopilensis

Classification: pf_cenozoic -> Truncorotaloididae -> Acarinina -> Acarinina praetopilensis
Sister taxa: << < A. pseudosubsphaerica, A. alticonica, A. soldadoensis, A. cuneicamerata, A. angulosa, A. africana, A. sibaiyaensis, A. esnehensis, A. mckannai, A. subsphaerica ⟩⟨ A. bullbrooki, A. punctocarinata, A. boudreauxi, A. rohri, A. topilensis, A. praetopilensis, A. mcgowrani, A. quetra, A. pseudotopilensis, A. wilcoxensis, A. esnaensis, A. primitiva, A. coalingensis, A. nitida, A. strabocella, A. sp.


Citation: Acarinina praetopilensis (Blow 1979)
Rank: Species
Basionym: Globorotalia (Truncorotaloides) topilensis praetopilensis
Taxonomic discussion: Acarinina praetopilensis was named by Blow (1979) for middle Eocene descendants of A. pseudotopilensis that show more closely appressed chambers in the last whorl leading to laterally angulate chambers and enhanced circum-peripheral concentration of partially fused muricae into a muricocarina on the last chamber. [Berggren et al. 2006]

Catalog entries: Globorotalia (Truncorotaloides) topilensis praetopilensis

Type images:

Distinguishing features: Test strongly muricate, subquadrate; last chamber disjunct, cuneate to mitriform lwith heavy circum-peripheral concentration of partially fused muricae.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.


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

Morphology: Low-trochospiral, sutures radial, straight, sunk (depressed) between overlapping junction(s) of juxtaposed inflated chambers; umbilicus deep and wide with no circum-umbilical muricate rim/collar; weakly rimmed aperture extends towards (but does not reach) the periphery; 9-10 chambers in 2-2½ whorls on spiral side; chambers tangentially longer than radially broad; last chamber distinctly disjunct, cuneate or mitriform, subacute margin with profusion/concentration of partially fused muricae; supplementary apertures usually present between the last two chambers in well preserved individuals; spiral sutures radial to weakly curved; in edge view high, angulo-conical. [Berggren et al. 2006]

Size: Maximum diameter of holotype: 0.38mm (Blow, 1979, p. 1043). [Berggren et al. 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:N/A
umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
spiral sutures:Strongly depressedumb depth:Deepwall texture:Coarsely muricateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:3.0-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology

Geographic distribution: Widespread distribution in Tethyan and South Atlantic regions. [Berggren et al. 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Berggren et al. (2006b)

Isotope paleobiology: Relatively negative ∂18O and positive ∂13C indicate a mixed layer habitat. Size fraction data shows a large change in ∂13C through ontogeny suggestive of a symbiotic relationship like other muricate forms (Boersma and others, 1987; Pearson and others, 1993; recorded as pseudotopilensis). [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): Boersma et al. (1987) Pearson et al. (1993)

Phylogenetic relations: Probably evolved from Acarinina mcgowrani n. sp. by greater lateral compression of, and concomitant concentration of partially fused muricae on, margins of last chamber, greater laxity in coiling mode and resulting larger and deeper umbilicus, and development of rimmed supplementary apertures between (at least) the last two chambers (Blow, 1979). It gave rise to Acarinina topilensis by developing a more distinctly lobate periphery, disjunct chamber margins on later chambers which exhibit pronounced cuneate or mitriform shape, stronger/heavier concentration of thick muricae on chambers of the last whorl, looser coiling resulting in even wider umbilicus than in praetopilensis and larger and greater number of supplementary apertures on spiral side. [Berggren et al. 2006]

Most likely ancestor: Acarinina mcgowrani - at confidence level 4 (out of 5). Data source: Berggren et al. (2006) fig9.2.
Likely descendants: Acarinina topilensis; Morozovelloides bandyi;

Biostratigraphic distribution

Geological Range:
Notes: to Zone E12.
Zone E7 (upper part) [Berggren et al. 2006]
Last occurrence (top): within E12 zone (39.97-40.40Ma, top in Bartonian stage). Data source: Eocene Atlas
First occurrence (base): in mid part of E7a subzone (50% up, 49.3Ma, in Ypresian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 300


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

Boersma, A., Premoli Silva, I. & Shackleton, N. J. (1987). Atlantic Eocene planktonic foraminiferal paleohydrographic indicators and stable isotope paleoceanography. Paleoceanography. 2: 287-331. gs

Pearson, P. N., Shackleton, N. J. & Hall, M. A. (1993). Stable isotope paleoecology of middle Eocene planktonic foraminifera and multi-species isotope stratigraphy, DSDP Site 523, South Atlantic. Journal of Foraminiferal Research. 23: 123-140. gs

Pearson, P. N. et al. (2004). Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1–5. Journal of African Earth Sciences. 39: 25-62. gs

Wade, B. S. (2004). Planktonic Foraminiferal biostratigraphy and mechanisms in the extinction of Morozovella in the Late Middle Eocene. Marine Micropaleontology. 51: 23-38. gs

Wade, B. S., Kroon, D. & Norris, R. D. (2001). Orbitally forced climate change in the Late Middle Eocene at Blake Nose (Leg 171B): Evidence From Stable Isotopes In Foraminifera. Geological Society of London, Special Publications. 183: 273-291. gs


Acarinina praetopilensis compiled by the pforams@mikrotax project team viewed: 18-4-2021

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