GuastiSpeijerpl1 f01-03.JPG
holotype illus_1107.jpg
GuastiSpeijerpl2 f01-03.JPG
This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.
GuastiSpeijerpl1 f01-03.JPG
holotype illus_1107.jpg
GuastiSpeijerpl2 f01-03.JPGLinked specimens: London, UK; NHM (PM P 45628) London, UK; NHM (45629)
Current identification/main database link: Acarinina sibaiyaensis El Naggar 1966
Original Description
Diagnosis. - A Globorotalia with small, globular, elongate test, slightly compressed in early part and inflated later; heavily spinose surface; narrow umbilicus: radial depressed sutures and long narrow aperture.
Description. - Test very small, globular, slightly compressed, coiled in a very low trochospire: dorsal side almost flat in the early part, inflated later: ventral side moderately inflated; equatorial periphery roughly ovoid, distinctly lobate and heavily spinose; axial periphery rounded : chambers on the dorsal side 12, arranged in two dextrally coiled whorls; the initial chambers are small, inflated, globigerine, and increase slowly in size; the last whorl is composed of 5½ relatively large, roughly globular chambers which increase gradually in size; on the ventral side the chambers are 5½, relatively large, subglobular, slightly inflated in the early part, more strongly so later; sutures on the dorsal side very slightly curved, depressed: on the ventral side they are straight, radial and strongly incised; umbilicus small, shallow and open ape rture interiomarginal, extra umbilical-umbilical, a narrow, long slit extending from the umbilicus to the periphery: wall calcareous perforate; surface spinose and nodose.
Size: Maximum diameter 0.29 mm.; minimum diameter 0.19 mm. : thickness of last chamber 0.17 mm.
Extra details from original publication
Remarks. - Globorotalia sibaiyaensis El-Naggar is distinguished from G. perclara Loeblich and Tappan, from which it is believed to have evolved, by its smaller test, entirely and heavily spinose surface, much narrower umbilicus and long slit-like aperture. It is distinguished from G. uncinata uncinata Bolli by its smaller size, globular form, heavily spinose surface and radial incised intercameral sutures. Globorotalia intermedia (Subbotina) differs from the present species in being more robust, more inflated on the ventral side and almost flattened on the dorsal, and in having fewer chambers which increase rapidly in size, and are strongly protruding on the ventral side, with closely adjacent umbilical ends. Globorotalia sibaiyaensis also appears to be morphologically similar to the holotype of the much younger G. rugosoaculeata (Subbotina) which is distinguished by its raised initial part.""
El-Naggar, Z. R. (1966). Stratigraphy and planktonic foraminifera of the Upper Cretaceous-Lower Tertiary succession in the Esna-Idfu region, Nile Valley, Egypt, U. A. R. Bulletin of the British Museum (Natural History) Geology. supplement 2: 1-291. gs Guasti, E. & Speijer, R. P. (2008). Acarinina multicamerata n. sp. (Foraminifera): a new marker for the Paleocene–Eocene thermal maximum. Journal of Micropalaeontology. 27: 5-12. gs V OReferences:
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Globorotalia sibaiyaensis compiled by the pforams@mikrotax project team viewed: 6-3-2021
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