Catalog - Globorotalia mariae mariae

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Globorotalia mariae mariae

Citation: Globorotalia mariae subsp. mariae Salvatorini, Foresi, Riforgiato&Verducci 2011

Type sample (& lithostrat): Sample TCR02-94 of the Cretaccio Formation

Type age (chronostrat): Cretaccio Section. Langhian, Globigerinoides sicanus/Orbulina suturalis Zone, MMi4 (P. siakensis-P. glomerosa circularis Subzone, MMi4c)

Type locality: Cretaccio Islet (Tremiti Islands, southern Adriatic Sea).

Type repository: Sienna: Micropaleontology Laboratory of the Department of Earth Sciences, University of Siena (Via Laterina 8, 53100 - Siena, Italy).

Test profile slightly longer than large, with a low trochospire formed by 14 chambers. Five gradually enlarging chambers in the final whorl. Equatorial periphery weakly lobulate in correspondence of the earlier chambers of the final whorl, becoming more lobulate in the last growing stages. Spiral surface almost flat in the central area, inflated near the periphery; umbilical surface quite convex. Profile plane-convex in axial view. Periphery sub-rounded in correspondence of the earlier chambers of the last whorl, that becomes sub-acute in the final chamber.

Chambers tangentially longer than wide, crescentic, rather convex on the spiral side; triangular and convex in umbilical view, reaching the highest convexity around the umbilical area. The last chamber becomes sharper toward the leading section of the outer margin.

Sutures depressed on the spiral side because of chamber convexity, gently curved, that become very retroverse in their distal part; weakly curved and depressed on the umbilical side. Umbilicus narrow and open. Aperture an umbilical-extraumbilical low arched opening, bordered by a well-developed lip.

The surface is shiny, with a finely perforated wall texture.

They [the two subspecies] are named Globorotalia mariae mariae and Globorotalia mariae gratiae after Maria Grazia, the person to whom they are dedicated.

Intra-specific variability: the equatorial profile can be circular and, sometimes, it appears longer than in the holotype; the spiral surface can be almost flat, especially in the last chambers; the ventral surface is more or less convex around the umbilicus. On the umbilical side, the sutures can be distinctly curved, the umbilicus close, the aperture more or less low, with a variously developed lip. Many pustules often develop on the umbilical area, becoming less frequent towards the distal part of each chamber and towards the last chamber. Rarely the last chamber is much smaller than the penultimate, and may be abortive. Some rare specimens show six chambers in the final whorl.

Remarks: Globorotalia mariae mariae n. subsp. differs from G. peripheroronda Blow and Banner in having a more finely perforated test wall, a more shiny appearance, and more gently curved spiral sutures (in G. peripheroronda they are distinctly angular). Moreover, G. mariae mariae only exceptionally has six chambers in the last whorl, whereas G. peripheroronda specimens have usually more than five chambers. The new subspecies differs from G. praescitula Blow (Pl. 1, figs. 12-13) for its larger size, the generally more elongated equatorial profile, the chamber convexity and their different shape on the spiral side. In G. praescitula the surface of the chambers on the umbilical side is less inflated, especially around the umbilicus, and the axial profile is more acute.

Stratigraphic range: Middle Miocene, Langhian to Serravallian; from the G. sicanus-O. suturalis Zone (MMi4) (G. praescitula Subzone, MMi4b) to the lower part of the P. partimlabiata Zone (MMi7) (P. partimlabiata-G. druryi Subzone, MMi7a).

References:

Salvatorini, G., Foresi, L. M., Riforgiato, F. & Verducci, M. (2011). Salvatorini, G., Foresi, L. M., Riforgiato, F. & Verducci, M. (2011). Globorotalia mariae mariae and G. mariae gratiae: Two new planktonic Foraminifera from the Middle Miocene of the Mediterranean. Stratigraphy. 8(02-Mar): 189-198. Stratigraphy. 8(2-3): 189-198. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia mariae subsp. mariae Salvatorini, Foresi, Riforgiato&Verducci 2011

Globorotalia mariae mariae

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