Catalog - Globorotalia (Turborotalia) peripheroacuta

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.

Globorotalia (Turborotalia) peripheroacuta

Citation: Globorotalia (Turborotalia) peripheroacuta Blow & Banner 1966

Type specimens: Plate I, figure 2a-c; plate 2, figures 4-5, 13; Holotype USNM no. 626072 (specimen same as that figured by Blow, 1959, pl. 17, fig. 112a-c, as a hypotype of "Globorotalia fohsi fohsi Cushman and Ellisor").

Type sample (& lithostrat): Auger sample RM. 19367; within the lower part o fthe Husito Marly Clay Member (at the top of the Siphogenerina transversa Zone), Pozón Formation.

Type locality: El Mene - Poz6n Road traverse, eastern Falcon, Venezuela (see Map no. 4, Blow, 1959)

Type repository: Washington, USNM

The test consists of about two and one-half whorls of chambers, five chambers in the whorl surrounding the proloculus, six and one-half chambers in the last-formed whorl. The chambers enlarge uniformly during test growth, the successive whorl heights being in the approximate ratio (as measured dorsally from the proloculus) 1:3:7. The test is completely evolute dorsally, and the dorsal surface is uniformly perforate; there is no conspicuous deposit of secondary laminae to obscure the early whorls, and there is no deposit of imperforate shell material in the dorsal intercameral sutures or the spiral suture. The dorsal sutures are shallowly and narrowly depressed. The dorsal intercameral sutures meet the weakly lobulate spiral suture at right angles, but in their distal parts are smoothly and strongly recurved, meeting the weakly lobulate outer periphery of the test at angles of about 45°.
The periphery is uniformly perforate throughout, and there is no carina. In axial profile, the periphery of the earlier chambers of the last whorl is broadly rounded, but the periphery becomes progressively more compressed as the last-formed chamber is approached, so that the last-formed three chambers possess acute peripheral margins.
The ventral surface of the test is more strongly convex than the dorsal surface, the ratio of ventral to dorsal convexity being about 3:1. The ventral side is completely involute, only the six and onehalf chambers which comprise the last whorl being visible. The ventral intercameral sutures are narrowly and shallowly depressed, are subradial but slightly sinuous, and meet both the very narrow, almost closed umbilicus and the weakly lobulate periphery approximately at right angles. The ventral chamber walls are uniformly perforate, and smooth except for a granular area on the earlier chambers immediately facing the aperture. The later chambers possess low, rounded umbilical shoulders. The ventral chamber walls between the umbilical shoulders and the periphery are weakly inflated in the first part of the last whorl, but become flattened during ontogeny, and even slightly concave in the last two chambers.
The apertural face is separated from the ventral face of the last chamber by a marked butsmooth change in slope. The texture ofthe apertural face and the ventral face is very similar. The apertural face is broadest near the periphery of the test and narrowest near the umbilicus; at its mid-point, the breadth of the apertural face is approximately equal to twofifths of its total length. The narrow, interiomarginal aperture extends from the umbilicus almost to the periphery of the test and is furnished throughout its length with a strong lip, broadest at the umbilical end.

The maximum diameter of the test is 0.39 mm.

Globorotalia fohsi fohsi Cushman and Ellisor. - BOLLI, 1950, p. 88, pi. 15, fig. 4a-c.- Bolli, 1957, p. 119 (part), pi. 28, fig. 10a-c only. - BLOW, 1959, p. 212, pi. 17, fig. I 12a-c (refigured here as holotype of n. sp., pi. 1, fig. 2a-c) (not G.johsi Cushman and Ellisor, 1939).
Globorotalia (Turborotalia) fohsi fohsi Cushman and Ellisor. - BANNER and BLOW, 1959, p. 22, pi. I, fig. 2a-c (not G. fohsi Cushman and Ellisor, 1939).

Comparison of species: G. (T.) peripheroacuta differs essentially from G. (T.) peripheroronda in possessing an acutely compressed periphery in the later chambers of the last whorl of the adult test.

References:

Blow, W. H. & Banner, F. T. (1966). The morphology, taxonomy and biostratigraphy of Globorotalia barisanensis LeRoy, Globorotalia fohsi Cushman and Ellisor, and related taxa. Micropaleontology. 12(3): 286-302. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia (Turborotalia) peripheroacuta Blow & Banner 1966

Globorotalia (Turborotalia) peripheroacuta

References:

Add Comment

Comments