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.
Linked specimens: USNM-170315 USNM-170314 USNM-170312 USNM-170313
Current identification/main database link: Planoglobulina riograndensis (Martin, 1972)
Test flabelliform, slightly compressed; Eight chambers in biserial portion; twenty-two chambers in multiserial portion. Chambers globular to pyriform. Sutures distinct, depressed. Fine, discontinuous segments of longitudinal costae cover majority of test, rearranging into a vermicular pattern on early chambers. Arched, basal apertures on front and back of all but outermost chambers in multiserial portion; outermost chambers usually with apertures on front only, facing inward.
Size: Holotype measures 575µm in length, 675µm in width, and 150µm, in maximum thickness. Other specimens vary from 475µm to 575µm in length; 400µm to 625µm in width; and 150, to 2OOµm in maximum thickness.
Extra details from original publication
Remarks: V . riograndensis, n. sp., superficially resembles V. glabrata Cushman in test shape, but differs in having vermicular ornamentation, fine, broken costae, and a less compressed test. The number of chambers in V. riograndensis varies from 23 to 34. Rarely, chambers in the last two rows (in well-preserved specimens) send finger-like extensions down into previously-formed chambers (PI. 2, fig. 2b). Vermicular ornamentation is well-developed on the early portion of most well-preserved specimens (pl. 2, fig. 4b).
Range: G. fornicata-stuartiformis Assemblage Zone, G. elevata Subzone (G. calcarata Zonule) to G . contusa-stuartiformis Assemblage Zone, A . mayaroensis Subzone.
Occurrence: In Mexico V. riograndensis occurs in the early Maestrichtian portion of the Mendez Shale (MX 13 and TYPE 4 of Pessagno, see appendix). In Puerto Rico V. riograndensis is found in the early Maestrichtian portion of the Rio Yauco Formation (OP 2690 of Pessagno, see appendix). V. riograndensis is abundant in sediments from the Maestrichtian (G. gansseri Subzone) portion of Site 21 of Joides Leg 111 from the Rio Grande Rise in the South Atlantic.
Martin, S. E. (1972). Reexamination of the Upper Cretaceous planktonic foraminifera genera Planoglobulina and Ventilabrella Cushman. Journal of Foraminiferal Research. 2(2): 73-92. gs Missing or ambiguous references: Pessagno 1976;
Martin, S. E. (1972). Reexamination of the Upper Cretaceous planktonic foraminifera genera Planoglobulina and Ventilabrella Cushman. Journal of Foraminiferal Research. 2(2): 73-92. gs
Missing or ambiguous references: Pessagno 1976;
Ventilabrella riograndensis compiled by the pforams@mikrotax project team viewed: 25-9-2020
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