Abstract

A new serial planktic foraminifer, Lipsonia lipsonae nov. gen., nov. sp., is reported from the Upper Maastrichtian sediments of the equatorial Central Pacific (Shatsky Rise). It presents raised sutures throughout, ornamentation consisting of coarse irregular structures on the early part of the test and smooth test surface in the adult stage. The absence of costate ornamentation suggests that the new taxon origins should probably be found in the contemporaneous non-costate species of the Laeviheterohelix glabrans-L. dentata group. Lipsonia lipsonae presents morphological similarities with the Santonian genus Sigalia. The costate test surface and sutures of the latter indicates that it evolved from a costate species. Accordingly, Lipsonia and Sigalia are the results of iterative evolution from two different heterohelicid groups.

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