Early Cretaceous planktonic foraminifera from the Tethys: the genus Leupoldina

Abstract

New findings of Early Cretaceous well-preserved planktonic foraminiferal assemblages from the Cismon core (NE Italy) and Calabianca section (NW Sicily) lead to a better understanding of the morphological features of several taxa. This paper deals with the revision of the taxa bearing radial chamber prolongations. Comparison of morphological characteristics between the genus Leupoldina Bolli, 1957 and Schackoina Thalmann, 1932 resulted in retaining Leupoldina as a valid genus that is distinguished from Schackoina by possessing radially elongate chambers ending with close, bulb-shaped extensions instead of open tubulospines. Moreover, the coiling mode in Leupoldina is pseudoplanispiral to trochospiral, whereas Schackoina is initially slightly trochospiral passing to planispiral, as supported by the asymmetry and symmetry of the aperture across the periphery, respectively. The species of the genus Leupoldina retained here areL. cabri Sigal, 1952, L. reicheli Bolli, 1957, and L. pustulans Bolli, 1957, among which three subspecies have been recognized on the basis of the number of chambers in the outer whorl; L. pustulans pustulans Bolli, 1957, L. pustulans quinquecamerata Bolli, 1957 and L. pustulans hexacamerata, subsp. nov. Stratigraphically,L. pustulans pustulans first appears in the Upper Barremian, L. cabri in the Lower Aptian just below the Selli Level, and the other taxa in the Upper Aptian above the Selli horizon. However, L. pustulans quinquecamerata and L. pustulans hexacamerata have ranges that are restricted to the lower part of the L. cabri Zone, whereas L. pustulans pustulans and L. reicheli range up to the base of the Globigerinelloides ferreolensis Zone.