Catalog - Rotalipora praebalernaensis

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Rotalipora praebalernaensis

Citation: Rotalipora praebalernaensis Sigal 1969

Type age (chronostrat): Upper Albian

Type locality: Diego Suarez well north of Raynaud, Madagascar, 121.2 m depth.

Type repository: Paris; Museum d'Histoire Naturelle de Paris

Translated from French:
Diagnosis: Species having the mode of coiling of balernaensis and evoluta but characterized by an imperfectly developed keel and by a more pronounced chamber globularity.
Description: Small-size test, finely and densely perforate; low trochospiral coiling lending the test an almost symmetrical profile; one can see 2 to 2.5 whorls of chambers regularly increasing (in size) and numbering, according to the form, 6 to 7.5 in the last whorl.
The periphery is marked by a single keel, which, at the beginning of the last whorl, consists of grouped protuberances the importance of which decreases gradually; finally the last 2-3 chambers showing only an angular edge consisting of a narrow band less densely perforate than the sides of the chambers; the outline of the test is clearly lobate.
The spiral side displays a last whorl- especially its last chambers- slightly lowered in comparison with the internal whorls. The chambers surface is slightly inflated, the sutures are curved, marked by a line of pustules which is the extension of the carinal ridge, then they become slightly depressed between the last chambers; each chamber overlaps the following, this arrangement being more noticeable when the suture is lined with pustules. The umbilical side displays quite inflated chambers separated by depressed, radial and straight sutures.
The chambers are typically triangular, gently dipping toward the umbilicus. No pustules or periumbilical ridges are present. The umbilicus is not very deep and small. The wall extensions fuse into a not-very-developed helicoidal ramp which does not cover the umbilicus. The apertural side is inflated, slightly higher than broad. The ornamentation of the internal whorls consists only of carinal protuberances.
The main aperture is semicircular, high, almost reaching the periphery; it is capped by a thin lip which combines with the wall extension. The supplementary aperture is very small, almost intraumbilical in position; the last one is bigger and more sutural; they are capped by thin lips. They are noticeable only in the last three chambers. It is noteworthy that, as shown in the last chamber, the supplementary aperture is barely separated from the posterior end of the main aperture by a downward fold of the wall extension.
No apparent preferred direction of coiling.

References:

Sigal, J. (1969). Contribution a une monographie des rosalines; II, L'espece Rotalipora appenninica (O. Renz, 1936), origine phyletique et taxonomie. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967. E J Brill, Leiden 622-639. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Rotalipora praebalernaensis Sigal 1969

Rotalipora praebalernaensis

References:

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