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Linked specimens: USNM-548876 USNM-548879 USNM-623952 USNM-548877 USNM-623953 USNM-548878
Current identification/main database link: Trilobatus bisphericus (Todd, 1954)
Test consists of two spheres of equal or nearly equal size, confluent in greater or less degree, one sphere consisting of the last-formed chamber, the other sphere consisting of the penultimate chamber strongly embracing all the previous ones, coiling dextral and sinistral. Sutures distinct and incised in individuals where the chambers are less embracing, indistinct in individuals where the chambers are more embracing. Wall calcareous, perforate, ornamented by a dense pattern of smalL delicate, round cancellations. Apertures two or more: in the case of individuals where the chambers are more embracing the apertures are irregular, narrow fissures appearing to result from the breaking apart of the test wall at the suture lines or suture junctions and usually bordered with irregular knobs of clear shell material: in the case of individuals where the chambers are less embracing the apertures are more distinct, low-arched openings into the final chamber, overhung by the rough, knobby edge of the chamber.
Size: Length 0.55-0.65 mm, greater diameter 0.45-0.50 mm.
Extra details from original publication
Remarks: This is the most abundant species in the upper Oligocene of Saipan. As described, it includes a rather wide range of shapes but is characterized by its bispherical form. Further studies of early Tertiary globigerinids are needed to determine the evolutionary relatives of this species.
The species has also been recorded under other names (see synonymy above) from the upper Oligocene of Trinidad and Ecuador. It is reported (R. M. Stainforth. letter of July 30, 1953, to Todd) to have had its acme during the short life-range of Globigerinatella insueta and to serve as a useful substitute marker for G. insueta in Venezuela where the latter is much less common than in Trinidad.
This species differs from Globigerinoides subquadrata Bronnimann, with which it occurs. in its circular, not compressed test, its less widely open apertures, and its finely cancellated wall. The individuals with strongly embracing chambers when poorly preserved may be confused with Orbulina suturalis Bronnimann and with Globigerinatella insueta Cushman and Stainforth but are distinguished by the faint trace of an equatorial suture line.
Name has often been corrected to Globigerinoides bisphericus Todd 1954 on the grounds that the genus is masculine
Globigerinoides bispherica compiled by the pforams@mikrotax project team viewed: 16-1-2021
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