NEOGENE OCCURRENCES OF THE MARINE ACRITARCH GENUS NANNOBARBOPHORA HABIB AND KNAPP, 1982 EMEND., AND THE NEW SPECIES N. GEDLII

Abstract

The stratigraphic utility of small marine acritarchs in the Neogene has been known for more than a decade (e.g., de Vernal and Mudie, 1989). Their potential for biostratigraphy in the Cretaceous is also well known, and was elegantly elucidated by Habib and Knapp (1982) in a detailed scanning electron microscope (SEM) study from the western North Atlantic. Habib and Knapp erected 12 new acritarch genera including the acanthomorph genus Nannobarbophora and its three species N. barbata (the name of the type), N. pistilla , and N. platforma . A diagnostic feature of Nannobarbophora is the presence of spinules concentrated on, or restricted to, the surface of distally closed processes. Excystment is by a simple linear split (Habib and Knapp, 1982, p. 347). The present study evaluates the taxonomy and biostratigraphy of Neogene species of Nannobarbophora by reappraising the literature and presenting new observations from the Miocene of Ocean Drilling Program (ODP) Hole 643A, Norwegian Sea (Fig. 1). The genus “ Svenkodinium ” Gedl, 1996, from the middle Miocene of Poland, is shown to be congeneric with, and junior to, Nannobarbophora . Two Neogene species of Nannobarbophora are now recognized, N. walldalei Head, 1996, and N. gedlii new species. The taxonomic and nomenclatural history of these species is clarified, and a better understanding of their biostratigraphy and widespread distribution is now attained. New observations of N. walldalei and N. gedlii n. sp. have required the emendation of Nannobarbophora . Figure 1 —Miocene–lower Pleistocene records of the genus Nannobarbophora . 1, ODP Hole 643A, Voring Plateau, Norwegian Sea (this study); 2, ODP Hole 644A, Voring Plateau, Norwegian Sea (Head, 1996; this study); 3, eastern England (Head, 1994, 1996, 1998); 4, Korytnica Clays, Poland (Gedl, 1996); 5, Singa section, southern Italy (Versteegh, 1994, 1995; Versteegh …