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Linked specimens: USNM-641569
Current identification/main database link:
Test free, trochospiral, about 2 1/2 whorls, convex on spiral side, slightly concave to convex on umbilical side, umbilicus small, deep when open, or may be covered, outline lobulate, circular in small specimens, quadrate in large ones, edges broadly rounded on umbilical side, more sharply rounded on spiral side. Chambers inflated, spherical in early stages, becoming elongate tangential1y, chambers larger where adjacent to earlier chambers, then tapering and becoming smaller toward aperture, 4 to 5 in last whorl, latest chambers tend to coil onto umbilical side of test, final chamber commonly reduced and covering umbilicus. Sutures radial, depressed, more deeply incised on umbilical side. Wall smooth, very finely perforate. Aperture extraumbilical, semicircular, with small protruding lip, commonly covered by small modified terminal chamber with an umbilical-extraumbilical opening.
Size: Greatest diameter of holotype .204 mm; greatest thickness .136 mm.
Etymology: The specific name is from the Latin opertus, meaning "cover, hide," in reference to the covered or hidden aperture and umbilicus.
Extra details from original publication
Remarks: This new species is differentiated from other species by its tangentially elongate, tapering chambers. Globorotalia acostaensis Blow, 1959, and G. birnageae Blow, 1959, are similar to E. operta but the chambers are not as wide in the former. The generic assignment of Blow's species could not be determined from the original descriptions and illustrations, and they may not be related to Eoglobigerina.
Eoglobigerina operta compiled by the pforams@mikrotax project team viewed: 28-10-2020
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