Original article A new Late Cretaceous (Maastrichtian) serial planktic foraminifer (Family Heterohelicidae) with early planispiral coil and revision of Spiroplecta Ehrenberg, 1844 § Un nouveau taxon maestrichtien de foraminifère planctonique sérié (Famille Heterohelicidae) au stade juvénile planispiralé et révision du genre Spiroplecta Ehrenberg, 1844 Marius Dan Georgescu a, * , Sigal Abramovich b a Department of Geoscience, University of Calgary, 2500, University Drive NW, Calgary, Alberta T2N 1N4, Canada b Department of Geological and Environmental Sciences, Ben Gurion University of the Negev, PO Box 653, Beer Sheva 84105, Israel Received 8 December 2008; accepted 11 June 2009 Available online 30 September 2009 Abstract A new planktic foraminifer, Hartella harti nov. gen., nov. sp. is described from the Maastrichtian sediments of the Atlantic Ocean. H. harti likely evolved from Fleisherites glabrans (Cushman). Spiroplecta Ehrenberg is reviewed and considered monospecific. The only species assigned to this genus is Spiroplecta americana Ehrenberg, which evolved from Heterohelix globulosa (Ehrenberg). It is demonstrated that the early planispiral coil developed in at least three separate lineages of serial planktic foraminifera in the Late Cretaceous (late Campanian-early Maastrichtian). # 2009 Elsevier Masson SAS. All rights reserved. Keywords: Planktic foraminifera; Late Cretaceous; Taxonomy; Hartella harti nov. gen., nov. sp Résumé Un nouveau taxon de foraminifère planctonique, Hartella harti nov. gen., nov. sp. est décrit dans les sédiments maestrichtiens de l’Océan atlantique. H. harti a évolué à partir de Fleisherites glabrans (Cushman). Le genre Spiroplecta Ehrenberg est révisé et considéré comme monospécifique. La seule espèce attribuée à ce genre est Spiroplecta americana Ehrenberg, qui a évoluée à partir d’Heterohelix globulosa (Ehrenberg). Nous démontrons que l’enroulement planispiralé des stades précoces du développement a évolué indépendamment chez trois lignées de foraminifères planctoniques sériés au cours du Crétacé récent (Campanien récent–Maestrichtien ancien). # 2009 Elsevier Masson SAS. Tous droits réservés. Mots clés : Foraminifères planctoniques ; Crétacé récent ; Taxinomie ; Hartella harti nov. gen., nov. sp 1. Introduction Recent taxonomic studies on Cretaceous planktic foramini- fera with serial chamber arrangement (Family Heterohelicidae Cushman, 1927) revealed that the group requires broad revision (Georgescu, 2007a, 2007b, 2008, 2009a, 2009b; Georgescu and Almogi-Labin, 2008; Georgescu and Abramovich, 2008a, 2008b; Georgescu et al., 2009). Extensive use of the Scanning Electron Microscope (SEM) showed that test ornamentation, ultrastructure and porosity are pivotal characters that can be used to successfully recognize phylogenetic relationships between species. Furthermore, the ancestor–descendant relationships between species can be used to define phylogenetic units at generic and even suprageneric level (Georgescu, 2009a). The refined taxonomic criteria had as prime consequence the increase in the number of genera, which nearly doubled in less than three years, and the process is far from being ended. Development of a new taxonomic framework for Cretaceous (upper Albian–Maastrichtian) heterohelicids is extremely Geobios 42 (2009) 687–698 § Corresponding editor: Frédéric Quillévéré. * Corresponding author. E-mail address: dgeorge@ucalgary.ca (M.D. Georgescu). 0016-6995/$ – see front matter # 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.geobios.2009.06.001