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Clarification of the systematic position of two calcareous dinoflagellate taxa belonging to the genus Calciodinellum (Dinophyceae, Peridiniales)

¹ Uppsala University, Department of Geosciences, Palaeobiology, Villavägen 16, 75236 Uppsala, Sweden, email: michael.streng@geo.uu.se
² University of Oslo, Department of Geosciences, P. O. Box 1047 Blindern, 0316 Oslo, Norway
³ The Natural History Museum, Palaeontology Department, Cromwell Road, London SW7 5BD, England
⁴ Natural Resources Canada, Geological Survey of Canada (Atlantic), P. O. Box 1006, Dartmouth, Nova Scotia, Canada, B2Y 4A2

The first 20% of the full text of this article appears below.

	INTRODUCTION

 
In an attempt to tidy up some previously published nomenclatural inconsistencies in their index of fossil dinoflagellates, Fensome and Williams (2004) inadvertently proposed transfers to two taxa that are not consistent with the current understanding of calcareous dinoflagellates. They proposed the transfers of Sphaerodinella? tuberosa forma elongata Hildebrand-Habel, Willems and Versteegh 1999 to Pernambugia as Pernambugia tuberosa forma elongata, and Sphaerodinella? tuberosa forma variospinosa Hildebrand-Habel, Willems and Versteegh 1999 to Pernambugia as Pernambugia tuberosa forma variospinosa. In order to clarify the systematics of these taxa and bring the taxonomy into line with current concepts, we herein propose the new combinations Calciodinellum elongatum and Calciodinellum levantinum forma variospinosum.

The classification of calcareous dinoflagellates is currently in the early stages of re-assessment using molecular data; the eventual goal is to unify cyst-based (= paleontological) and motile-based (= neontological) taxonomy (see Gottschling et al. 2005 for details). Initial results from molecular studies support the taxonomic concept developed by Streng et al. (2002), who used a combination of ultrastructural and archeopyle details of cysts to distinguish genera. Thus, species within each genus should have a consistent ultrastructure and archeopyle type as well as an equivalent motile stage.

The genus Pernambugia Janofske and Karwath in Karwath 2000 is characterized by an epitractal archeopyle (pl. 1, fig. 8) and oblique ultrastructure (Janofske and Karwath in Karwath 2000; Streng et al. 2004a), whereas Calciodinellum has a mesoepicystal archeopyle (sensu Streng et al. 2004a. . . [Full Text of this Article]