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Linked specimens: USNM-211508 USNM-211506 USNM-211509 USNM-211507
The robust test is of moderate size, and consists of eight or more chambers arranged in a low trochospire, with four chambers in the final whorl. The wall texture is distinctly cancellate with well-developed pore pits. The dorsal surface is weakly convex, and the chambers are closely appressed. The earlier whorls are somewhat obscured, but the wall does not appear to be significantly thickened over the initial chambers. Dorsal sutures are slightly depressed, straight, and radial to slightly tangential. In outline the test is subquadrate, and the periphery is somewhat lobate and broadly rounded. The chambers are subglobular throughout. Ventral convexity is slightly greater than that of the dorsal side. The ventral sutures are straight and distinctly incised. The final chamber is typically larger and somewhat more inflated than the earlier chambers of the final whorl and projects slightly out of the plane of coiling. There is no distinct umbilicus, except in some occasional and somewhat atypical specimens (Plate 20, Figure 5), but a poorly defined umbilical depression is present. The large open aperture is umibilical to extraumbilical in position, but typically oblique in orientation, much as in T. (T.) cerroazulensis pomeroli (Toumarkine and Bolli). In rare specimens, however, it is laterally directed. The aperture is bordered by a broad, well-developed, imperforate rim.
Size: Maximum diameter of the holotype is 0.34 mm; axial elevation is 0.24 mm.
Etymology: This species is named for Dr. Catherine Nigrini, a co-participant on DSDP Leg 23. Stratigraphic Range: Middle N.18 to late N.19-N.20 (Early to mid-Pliocene).
Extra details from original publication
Remarks: This distinctive species most resembles T. (T.) pseudopima, from which it differs in possessing a large, open, oblique aperture. It differs from T. (T.) continuosa in having a less-flattened dorsal side and more rapid increase in chamber size prior to the final whorl and in the shape and orientation of the aperture. In T. (T.) continuosa the aperture is more rounded ("comma-shaped"") and is laterally rather than obliquely directed."
Turborotalia (Turborotalia) nigriniae compiled by the pforams@mikrotax project team viewed: 21-9-2021
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