Catalog - Sphaeroidinella cellata

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Sphaeroidinella cellata

Citation: Sphaeroidinella cellata Subbotina, in Bykova et al. 1958

Type specimens: pl. 11, figs. 4-5, exterior views, X 72; 4a-c,holotype : ; holotype, no . 440-60; and "original," no. 440-61.

Type sample (& lithostrat): Balichskaya Series; very abundant, in a light green-gray marl.

Type age (chronostrat): Middle Miocene, Helvetian

Type locality: Holotype from a depth of 44.0-7 meters in well no. 8, in the Bogorodchany region of Staniskalskiy Oblast, in the western part of the Ukrainian S.S.R.

Type repository: Leningrad; All-Union Petroleum Scientific Research Geological Prospecting Institute (VNIGRI) , Leningrad

Translation from the Russian. - Test strongly tumid, very compact. in the adult stage consisting of two or three spiral whorls. In the early whorl there are three. frequently four, rarely five, small chambers, rather sharply distinguished in size, closely adjoining one another ; in exterior view, only a small part of them is visible, protruding weakly above the general surface of the test, the basic parts of the chambers of the first and even the second whorl being found within the cavity of the test. In size, the entire early whorl corresponds to only one chamber of the succeeding second whorl. The second whorl usually consists of three spherical chambers, the walls of which are thick, not differing from the walls of the chambers of the final whorl. There is considetable difference between the size of the chambers of the second and particularly the third and final whorl, always easily noticeable. The final chamber, sometimes constituting one-half of the entire test. is exteriorly semispherical. All chambers adjoin closely. Peripheral margin weakly lobate, nearly smooth. Sutures slightly curved, somewhat depressed. Wall thick, without any trace of spines, coarsely perforate, exteriorly alveolar; that is, near each pore there is a funnel - shaped dpression. Aperture deep slits along the equatorial suture , separating the final chamber from the two preceding ones. Usually one or two such slits are well marked. One of these occurs in the middle: of the ventral side at the place where three sutures meet to form a "T" these sutures separating the last three chambers; the other is on the dorsal side, diametrically opposite to the first. Margins of slits frequently serrate. Aperture on each side usually equal to one-third the " semiequator" that is, one-third of one-half the length of the entire suture separating the last chamber.

Dimensions. - Holotype , greatest diameter 0.40 mm.; least diameter 0.30 mm. ; thickness 0.30 mm. "Original," greatest diameter 0.35 mm . ; least diameter 0.30 mm. ; thickness of final chamber 0.25 mm.

In general aspect. in the number of chambers, their shape and arrangement, as well as in the character of the apcrture, this species corresponds complete to the genus Sphaeroidinella.
Variable features are as follows: 1) The number of whorls (besides two-whorled adult forms there are also ones with three whorls in the spiral); 2) the relative size of the chambers and their shape: Besides nearly regularly spherical chambers, there are frequently ones somewhat elongate; the elongation is particularly well expressed in the final chamber. In such instances the test has a more narrow, oval outline, not broadly oval as in the most typical specimens; 3) the character of the aperture; instead of two slits there frequently is one (the other, apparently, cicatrice). The length of the slit and its serrate margins are also variable features. There are very short, barely noticeable slits, and very long ones, nearly contiguous with one another. Rarely there are forms with an apertural slit as in Sphaeroindlnella dehiscens (Parker and Jones) [Sphaeroidina bulloides dehiscens, 1865], that is, engirdling the entire test, more frequently with two or one short slits. In the latter instance, the slit is marked on the ventral side, and rarely on the dorsal side . Marginal serration may be more or less distinct. sometimes not observed at all, perhaps because the serrations arc broken off.
The described species differs from the Recent Sphaeroidinella dehiscens in the lesser length of the aperture and the smaller serrations. It differs from Sphaeroidinella spinulosa Subbotina , from the Pliocene (Plaisancian) of Albania, in the smaller size and the absence of the characteristic spinosity.
Judging by the fact that the close Recent Sphaeroidinella dehiscens, the type of the genus Sphaeroidinella, is widely distributed in the tropical and subtropical regions of the Atlantic and elsewhere, our species also probably existed in nearly subtropical conditions. This is all the more true since it is always found associated with large and thick-walled globigerinids, along with abundant Candorbulina and Globigerinoides, also close to Rcent forms from tropical and subtropical zones.

References:

Bykova, N . K., et al. (1958). Новые роды и виды фораминифер - New genera and species of foraminifera. Микрофауна CCCR СБОРНИК IX, Microfauna of the USSR - part IX. Trudy Vsesoyuznego Neftyanogo Nauchno-Issledovatel'skogo Geologo-Razvedochnogo Instituta (VNIGRI). 115: 5-106. gs O

Subbotina, N. N. (1958). In: Bykova, N.K., et al., New genera and species of foraminifera. Trudy VNIGRI Mikrofauna USSR. 115(9): 58-61. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Sphaeroidinella cellata Subbotina, in Bykova et al. 1958

Sphaeroidinella cellata

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