Acarinina medizzai

Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Acarinina -> Acarinina medizzai
Sister taxa: A. medizzai, A. collactea, A. pentacamerata, A. aspensis, A. echinata, A. pseudosubsphaerica, A. alticonica, A. soldadoensis, A. interposita, A. cuneicamerata, A. angulosa, A. africana, A. sibaiyaensis, A. esnehensis, A. mckannai, > >>


Citation: Acarinina medizzai (Toumarkine & Bolli 1975)
Rank: Species
Basionym: Globigerina medizzai
Taxonomic discussion: This species is closely related to, and possibly synonymous with, Acarinina rugusoaculeata Subbotina. The latter was distinguished from A. medizzai by Toumarkine and Bolli (1975) on having a more umbilically positioned aperture and based on the presence of a final chamber that is larger and less detached from the previous chambers. Although Subbotina described her species as having a slit-like aperture that extends along the sutural margin, the apertural position in the holotype is not apparent from the illustration (e.g., Subbotina, 1953, pl. XXV: figs. 4a, b), and one of the other illustrated specimens that clearly does have an extraumbilical aperture and was designated as A. rugosoaculeata by Subbotina (1953, pl. XXV: figs. 6a, b) lacks a muricate wall texture and therefore should not be included in Acarinina. This ambiguity cannot be cleared up from study of Subbotina’s collection since the holotype and other specimens originally assigned to A. rugosoaculeata have been lost (E .M. Bugrova, pers. comm., 2003). Until specimens from the type level of the A. rugosoaculeata holotype can be studied and compared with A. medizzai we have chosen to suppress A. rugosoaculeata in favor of recognition of the better-documented species A. medizzai. [Berggren et al. 2006]

Catalog entries: Acarinina rugosoaculeata;
Globigerina medizzai;

Type images:

Short diagnosis: Differs from A. collactea by its smaller size and smaller, often indistinct aperture; differs from A. echinata by absence of a bulla and by presence of an umbilicus; differs from
Dipsidripella danvillensis (Howe and Wallace) in presence of a bilamellar, rather than monolamellar, wall and more densely muricate surface ornamentation.

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.


Diagnostic characters: Differs from A. collactea by its smaller size and smaller, often indistinct aperture; differs from A. echinata by absence of a bulla and by presence of an umbilicus; differs from
Dipsidripella danvillensis (Howe and Wallace) in presence of a bilamellar, rather than monolamellar, wall and more densely muricate surface ornamentation. [Berggren et al. 2006]

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

Test morphology: Test relatively small, biconvex, quadrate to subcircular in outline, weakly to moderately lobate with a rounded periphery; chambers globular, 8 to 12 arranged in a low trochospire of 3-4 whorls, increasing moderately in size, 4 to 6 in the final whorl, rarely kummerform; umbilicus narrow in more compact specimens, shallow and broad in more evolute forms; sutures moderately depressed, radial on both sides; aperture a small and often indistinct low umbilical to slightly extraumbilical arch. [Berggren et al. 2006]

Size: Maximum diameter of holotype 0.19 mm; tests sizes range from 0.16 to 0.20 mm. [Berggren et al. 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:
umb chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:N/A
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Shallowwall texture:Finely muricateshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.19width mm:breadth mm:
final-whorl chambers:4.0-6.0

Biogeography and Palaeobiology

Geographic distribution: This species has a cosmopolitan distribution but is often unreported, perhaps because of its small size and/or incorrect identification. [Berggren et al. 2006]
Aze et al. 2011 summary: Cosmopolitan; 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: Probably descended from Acarinina collactea during middle Eocene Zone P12 (=Zone E10 of this paper). [Berggren et al. 2006]

Most likely ancestor: Acarinina collactea - at confidence level 4 (out of 5). Data source: Berggren et al. (2006) fig9.2.

Biostratigraphic distribution

Geological Range:
Notes: Zone E10 to Zone E14. Toumarkine and Bolli (1975) recorded the range of A. medizzai from the Globorotalia lehneri Zone to the base of the G. semiinvoluta Zone (upper middle to upper Eocene). Poag and Commeau (1995) noted that in the Hammond Core, southwestern Salisbury Embayment, Maryland coastal plain, “Zone P15” was recognized by the overlap of the lower range of Pseudohastigerina naguewichiensis and the occurrence of Globigerina (vel Acarinina) medizzai. However, in ODP Hole 1053A the highest occurrence of A. medizzai has been recorded in Sample 1053A-3H-4, 105 cm, in Chron C16n.2n, which is stratigraphically equivalent to Zone E14 (Wade, 2004). Although Subbotina (1953) recorded muricate forms assigned to A. rugosoaculeata (e.g., Subbotina, 1953, pl. XXV: figs. 5a-c) in the (questionable) lower-middle Oligocene of the northern Caucasus region, no forms that are currently identified as A. medizzai (? =A. rugosoaculeata) have been recorded above Zone E14 elsewhere to our knowledge. [Berggren et al. 2006]
Last occurrence (top): within E14 zone (35.89-37.99Ma, top in Priabonian stage). Data source: Eocene Atlas
First occurrence (base): in upper part of E10 zone (80% up, 42.2Ma, 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. 292


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.

Poag, C.W. & Commeau, J.A., (1995). Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: Biostratigraphy, allostratigraphy, and sequence stratigraphy. Journal of Foraminiferal Research, 25: 134-155.

Spezzaferri, S., (1998). Planktonic foraminiferal biostratigraphy and paleoenvironmental implications of Leg 152 sites (East Greenland Margin). Proceedings of the Ocean Drilling Program, Scientific Results, 152: 161-190.

Subbotina, N., (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres, 2239: 1-144.

Toumarkine, M. & Bolli, H.M., (1975). Foraminifères planktoniques de l'Eocène moyen et supérieur de la coupe de Possagno. Schweiz. Palaontol. Abh., 97: 69-185.

Toumarkine, M. & Luterbacher, H., (1985). Paleocene and Eocene planktic foraminifera. Plankton Stratigraphy. Cambridge Univ. Press, Cambridge, 87-154 pp.

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


Acarinina medizzai compiled by the pforams@mikrotax project team viewed: 20-1-2018

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