CATALOG OF ORIGINAL DESCRIPTIONS: Truncorotaloides rohri var. guaracaraensis Bronnimann & Bermudez 1953

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 -> T -> Truncorotaloides -> Truncorotaloides rohri guaracaraensis
Other pages this level: T. haynesi, T. libyaensis, T. rohri, T. rohri guaracaraensis, T. rohri mayoensis, T. rohri piparoensis

Truncorotaloides rohri guaracaraensis

Citation: Truncorotaloides rohri var. guaracaraensis Bronnimann & Bermudez 1953
Rank: Variety
Type locality: Duff Road area, near Kelly Junction, about 7 miles east of Pointe-a-Pierre, central Trinidad, B.W.I. Found also at Jaruco, Province of Habana, Cuba; and at the type locality of the Guayabal formation, State of Vera Cruz, Mexico.
Type age (chronostrat): Eocene
Type sample (& lithostrat): in the finely pebbly, heterogeneous matrix of a marl-pebble bed. Occurs also in a lower to middle Eocene marl (Jarucol, and in the Eocene Guayabal formation (Vera Cruz). Abundant.
Type specimens: Plate 87, figures 1-3; Holotype.-T.L.L. Cat. No. 172694.: Other specimens personal collections of P. Bronnimann.
Type repository: USNM

Linked specimens: USNM-4235

Current identification/main database link: Acarinina rohri (Bronnimann & Bermudez 1953)


Original Description
The general outline of the low trochoidal test is almost ellipsoid. The slightly convex spiral side shows ten to eleven chambers arranged in two volutions. The adult test has five to six chambers. The appressed subglobular chambers increase gradually in size. The chambers of the final whorl, in particular the end chamber, are peripherally flattened in side view. The umbilicus is rather small and deep. The straight sutures are well marked in the adult, but indistinct in the strongly spinose young ontogenetic stage. The large arcuate apertures of the last two chambers open directly into the umbilicus. Those of the preceding chambers are not known. The apertures are surrounded by thin lip-like borders. At the spiral side, additional small, arcuate openings with minute lip-like borders pierce the three last-formed chambers at the intersections of radial sutures and periphery of the preceding volution. It is not known whether openings of this type exist in earlier chambers. The surface is uniformly covered by small, heavy spines, which are strongly developed on the early chambers and at the rounded umbilical parts of the adult chambers. The walls are thick and perforate. Nineteen out of twenty-one well-preserved specimens are sinistrally coiled.

Size: Dimensions - Maximum diameter of test 0.375 mm. End chamber: Radial diameter 0.125 mm.; tangential diameter 0.2 mm.; height 0.215 mm. Diameter of aperture 0.05-0.08 mm.; of additional spiral opening 0.05 mm.

Etymology: named after the Guaracara River, central Trinidad.

Extra details from original publication
Discussion - Truncorotaloides rohri var. guaracaraensis is the variety with completely rounded chambers; this form could be interpreted as Globigerinoides Cushman. Transitions connect this variety and the more lobate and subangular Truncorotaloides rohri var. piparoensis Bronnimann and Bermudez. The tests can be arranged in two groups of slightly different maximum diameter. The holotype belongs to the larger tests.

References:

Brönnimann, P. & Bermudez, P. J. (1953). Truncorotaloides, a new foraminiferal genus from the Eocene of Trinidad, B.W.I. Journal of Paleontology. 27: 817-820. gs


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Truncorotaloides rohri guaracaraensis compiled by the pforams@mikrotax project team viewed: 30-7-2021

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