• Protentelloides primitiva Zhang and Scott, 1995:77, pl. 1, figs. 1a-d [upper Oligocene Zone P22, DSDP Hole 366A, eastern equatorial Atlantic Ocean].

We change the species name to its masculine form to accord with Article 31.2 of the ICZN (“a species-group name, if it is or ends in a Latin or latinized adjective or participle in the nominative singular, must agree in gender with the generic name with which it is at any time combined”). Thus Protentelloides primitiva becomes P. primitivus. Protentelloides primitivus has a similar wall texture to the proposed ancestor G. atlanticus. Pore density is much lower than in G. variabilis and G. stainforthi. Longer ranging than its descendant, it exhibits a wide range of morphological variability in both the number of final whorl chambers and the nature of coiling. The morphologies assigned to this morphospecies clearly shows overlap with P. dalhousiei. We choose to separate the two due to the slightly higher stratigraphic appearance of forms that consistently have near-planispirally coiled and an elaborate aperture system. There are no published occurrences of this taxon since its description in 1995. In our recent studies of Oligocene material we find it in ODP Site 667, which is near to DSDP Site 366, but not outside of the eastern equatorial Atlantic Ocean where these two sites lie. [Coxall & Spezzaferri 2018]

Large and distinctive, Protentelloides primitivus differs from Globorotaloides atlanticus n. sp., from which it evolved, by the more irregularly shaped and inflated chambers, the deeply depressed sutures, more lobate peripheral outline and the distinctly equatorial position of the terminal bulla-like chamber. It differs from Globorotaloides hexagonus (Natland) in possession of a bulla and the equatorial-umbilical aperture. It is distinguished from Protentelloides dalhousiei in the slightly more involute coiling, the transitional position of the primary aperture, which is umbilical to extraumbilical, and in lacking accessory apertures. It also typically has fewer chambers in the final whorl than P. dalhousiei. It differs from Protentella prolixa Lipps (1964) in the lower stratigraphic range, possession of a bulla-like final chamber and the coarse cancellate wall. The tendency towards elongation of the final chamber represents another example of evolutionary convergence on a digitate form. [Coxall & Spezzaferri 2018]

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