<i>Heterostegina matteuccii</i> sp. nov. (Foraminiferida: Nummulitidae) from the lower Oligocene of Sicily and Aquitaine: a possible transatlantic immigrant

The systematics and phylogenetic relations of the Oligocene species of <i>Heterostegina</i> (Nummulitidae) are poorly known compared to those of Eocene and Miocene species. The new species <i>Heterostegina matteuccii</i> sp. nov., characterized by the combination of an advanced nepionic stage (i.e. very few operculine chambers) and a relatively small proloculus, is here described from the lower Oligocene Caltavuturo Formation of Portella Colla (Madonie Mts, Sicily, Italy). The same species is recorded also in the ‘Calcaire à astéries’ Formation of Illats (Northern Aquitaine, near Bordeaux, France). Biometrically, <i>H. matteuccii</i> sp. nov. does not fit within any known Neo-Tethyan lineage of <i>Heterostegina</i> from the Eocene to the Miocene, and hence is considered to be a member of a distinct phyletic lineage. The advanced nepionic stage of <i>H</i>. <i>matteuccii</i> sp. nov., however, calls for the existence of predecessors. The Priabonian (and possibly also earliest Oligocene) <i>H</i>. <i>ocalana</i> Cushman, 1921 from the American-Caribbean realm is here interpreted as the most probable ancestral form for the <i>H</i>. <i>matteuccii</i> lineage. Thus, an early Oligocene eastward transatlantic migration of this lineage may be inferred. New results of strontium isotope stratigraphy from both sides of the Atlantic Ocean are consistent with this hypothesis. http://zoobank.org/urn:lsid:zoobank.org:pub:CC54DB64-091D-4CDE-A6AB-6DC620F0FC23