CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina arabica El-Naggar 1966

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.


Higher levels: pf_cat -> G -> Globigerina -> Globigerina arabica
Other pages this level: << < G. altispira, G. ampliapertura, G. ampliapertura cancellata, G. anconitana, G. angipora, G. angiporoides, G. angiporoides minima, G. angulata, G. anguliofficinalis, G. antarctica, G. antillensis, G. apertura, G. applanata, G. aptica, G. aquiensis, G. arabica, G. archaeobulloides, G. ariakensis, G. aspensis, G. aspera, G. asperula, G. atlantica, G. atlantis, G. atlantisae, G. aumalensis, G. ayalai, G. azerbaidjanica, G. baconica, G. bacuana, G. bakeri, G. balchanensis, > >>

Globigerina arabica

Citation: Globigerina arabica El-Naggar 1966
Rank: species
Type locality: Holotype (fig. 6a-c) and unfigured paratypes from approximately 93 meters above the base of the Gebel Owaina section (27°45'N 32° 45.75'E), about 12 km. north of the Nile at El Mahamid, Esna-Idfu region, Upper Egypt.
Type age: Lower Paleocene, Upper Danian, Globorotalia compressa/Giobigerinoides daubjergensis Zone,
Type sample and level: lower Owaina Shale.
Holotype Repository: London, UK; NHM
Type & figured specimens: holotype (fig. 6a-c) P.45570: unfigured para types, P.45571.

Linked specimens: London, UK; NHM (45571) London, UK; NHM (PM P 45570)

Current identification/main database link: Praemurica inconstans (Subbotina 1953)


Original Description
Diagnosis. - A Globigerina with large, moderately to highly spired. smooth-walled test : radial, incised sutures on both sides; chambers increasing slowly in size.

Description
. - Test large, globular, inflated and coiled in a high trochospire; dorsal side convex, strongly inflated with the early ch ambers almost on the same level and distinctly raised above those of the last whorl; ventral side moderately inflated; equatorial periphery subcircular, distinctly lobate: axial periphery rounded; the 18 chambers on the dorsal side increase slowly in size and are arranged in 2_ dextrally coiled whorls; the last whorl is composed of 6, large, subglobular chambers; on the ventral side the chambers are 6, large, globular, strongly inflated and increase slowly in size except for the third which is much smaller than the others; sutures on both sides almost straight, radial and strongly depressed; umbilicus small, deep and open (although it is filled with calcite growth and foreign material in the figured specimen); aperture interiomarginal umbilical, an ovoid, large opening with thick calcite growth around it; wa ll calcareous, perforate; surface smooth.  

Size: Maximum diameter 0.46 mm.; mm1mum diameter 0.39 mm.; maximum thickness across the middle part of test 0.29 mm. "

Extra details from original publication
Variation - The main variation observed is in the degree of elevation of the dorsal side which can be either weakly raised or coiled in a very high trochospire; coiling is random with more tendency to dextral forms.

Remarks. - Globigerina arabica El-Naggar is distinguished from G. spiralis Bolli by its much larger size, less elevated initial spire and more globular, inflated chambers. In G. spiralis each whorl is higher than the following one and thus the dorsal side is more or less conical in shape, while in G. arabica the first two whorls are more or less in the same level but distinctly higher than the last.
The presence of the peculiar calcite growth in the umbilicus and around the aperture made it difficult to determine the taxonomic position of this species with certa inty. It is, therefore, included in Globigerina for the time being on the basis of its other morphological features.
Globigerina arabica was probably evolved from Globorotalia trinidadensis Bolli by the elevation of the early whorls, the reduction of the rate of growth, and the confinement of the aperture to an interiomarginal, umbilical position. Forms of G. trinidadensis with slightly raised early chambers are believed to be transitional to the present species. G. arabica is also believed to have evolved into G. spiralis Bolli, as substantiated by the morphological characters and stratigraphical distribution of these two species.

References:

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


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Globigerina arabica compiled by the pforams@mikrotax project team viewed: 9-4-2020

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