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Species Globorotalia aequa Cushman & Renz 1942


Diagnosis / Definition:
Bolli (1957):
Shape of test. Very low trochospiral, spiral side flat to slightly convex, umbilical side strongly convex; equatorial periphery lobate; axial periphery acute, faint keel ornamented with spines occasionally observed. Wall calcareous, perforate, surface covered with fine spines in well preserved specimens. Chambers angular, inflated; about 10-12, arranged in 2 1/2 whorls; the 3-4 chambers of the last whorl increase rapidly in size. The last chamber may represent almost 50 percent of the surface of the test. Sutures on spiral side strongly curved, slightly depressed; on umbilical side radial, distinctly depressed. Umbilicus narrow, deep, open. Aperture a low arch; interiomarginal, extraumbilical umbilical. Coiling over 90 percent dextral. Largest diameter of figured hypotypes 0.40 mm.
Discussion / Comments:
Bolli (1957):
No close morphologic or stratigraphic connection is evident between Globorotalia aequa Cushman and Renz and the coarsely spinose G. crassata (Cushman) from the middle to upper Eocene. Specific rank is therefore given to G. aequa. It is distinguished from the related G. angulata (White) by having a more spinose surface, a relatively large ultimate chamber and in a distinct preference for dextral coiling. A comparison of the holotypes of G. aequa and G. lacerti Cushman and Renz clearly indicates that the latter is a junior synonym. G. aequa is regarded as the ancestor of G. rex Martin and G. formosa gracilis Bolli, new species, new subspecies.
Systematics:

20
 Genus Globorotalia
  Species Globorotalia angulata
   Species Globorotalia velascoensis
Synonym list:
Bolli (1957):
1942 Globorotalia crassata var. aequa Cushman & Renz. - Cushman & Renz : p. 12 pl. 3, figs. 3a-c
1946 Globorotalia lacerti Cushman & Renz. - Cushman & Renz : p. 47 pl. 8, figs. 11-12
1957 Globorotalia aequa Cushman & Renz. - Bolli : pl. 17, figs. 1-3; pl. 18, figs. 13-15
Was used in synonym list of:
Morozovella aequa Renz & Cushman 1942
Morozovella angulata White 1928
References:

Cushman,J.A. and Renz,H.H. (1942):
Eocene, Midway, Foraminifera from Soldado Rock, Trinidad . Contributions from the Cushman Foundation for Foraminiferal Research Vol. 18 p. 1-20

Cushman,J.A. and Renz,H.H. (1946):
The Foraminiferal Fauna of the Lizard Springs Formation of Trinidad, British West Indies . Cushman Laboratory for Foraminiferal Research, Special Publication Vol. 18 p. 1-48

Bolli,H.M. (1957):
The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad, B.W.I . Bulletin of the U.S. National Museum Vol. 215 p. 61-82
Anonymous: Unedited TaxonConcept data
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