Catalog - Globigerinella ultramicra Catalog - Globigerinella ultramicra

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerinella ultramicra Subbotina 1949

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 -> Globigerinella -> Globigerinella ultramicra
Other pages this level: G. aberranta, G. aissana, G. alexi, G. biforaminata, G. cushmani, G. duboisi, G. escheri clavata, G. evoluta, G. evoluta evoluta, G. gottisi, G. japonica, G. liverovskae, G. megaperta, G. messinae messinae, G. messinae subcarinata, G. naguewichiensis, G. praemicra, G. pseudovoluta, G. roeglina, G. subangulata, G. tururensis, G. ultramicra, G. voluta pinguis

Globigerinella ultramicra

Citation: Globigerinella ultramicra Subbotina 1949
taxonomic rank: Species
Type specimens: 1590
Type age (chronostrat): Cenomanian
Type locality: Kapustnaya Gorge, southern slope of the Caucasus
Type repository: St. Petersburg, Russia - VNIGRI

Current identification/main database link: Planohedbergella ultramicra (Subbotina, 1949)


Original Description

Test the smallest of all representatives of Globigerinella known to date. It is flat, rounded, and bilaterally symmetrical, but not involute. There are two whorls. Diameter of the first whorl disproportionately small in comparison with the diameter of the second whorl. In specimens with both sides well preserved, the chambers of the first whorl are visible in the median, depressed portion. Peripheral border rounded, lobate. Chambers almost spherical, slightly compressed laterally, very imperceptibly differing in size from one another. In the final whorl there are six to eight chambers. Sutures simple, weakly curved, almost straight, depressed. Aperture typical of the genus. Wall smooth.



Size:
Greatest diameter 0.14 mm.; smallest diameter 0.12mm.; thickness 0.06 mm

Extra details from original publication
Among the largest typical specimens there are oval tests with six or seven chambers in the final whorl, a disproportionately large final chamber, and strongly curved sutures. Several such specimens were found in the samples from the upper part of the Cenomanian. It is possible that later it will prove necessary to separate them into a new species. For the time being, however, we do not have sufficient material at our disposal. Specimens different from the typical ones, with a conspicuous difference in the size of the final two or three chambers in comparison with the first chambers of the final whorl, and with more strongly curved sutures have been found less frequently.

Because of the peculiar combination of such morphological features as the small size of the test, rounded outline, relatively large number and almost uniform size of the chambers of the final whorl, as well as the straight sutures, Globigerinella ultramicra is distinctly different from all other known species of this genus. Globigerinella aspera (Ehrenberg) [Phanerostomum asperum, 1854] which is stratigraphically the most closely related species, differs from our species in the larger size, the oval outline of the test, the considerably greater difference in the size of the chambers of the final whorl, and the distinctly spinous wall.

References:

Subbotina, N. N. (1949). Микрофауна меловых отложений южного склона Кавказа [Microfauna from the Cretaceous of the southern slope of the Caucasus]. Trudy VNIGRI Mikrofauna USSR. 34: 5-36. gs


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Globigerinella ultramicra compiled by the pforams@mikrotax project team viewed: 19-4-2024

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Comments (3)

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Le Coze

Original name: Globigerinella ultramicra (genus is feminine)

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Le Coze

According to Ellis and Messina the correct ref. is: original description Subbotina, N. N. (1949). Микрофауна меловых отложений южного склона Кавказа - Microfauna from the Cretaceous of the southern slope of the Caucasus. VNIGRI, Microfauna of the oil fields of the USSR. 2(34): 5-36.

page(s): p. 33 pl. 2 fig. 17-18

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Jeremy Young

thanks for those - and ending corrected now