Clarification of the systematic position of two calcareous dinoflagellate taxa belonging to the genus Calciodinellum (Dinophyceae, Peridiniales). Micropaleontology, 52(2): 189-192.
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 concepts 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 (Fig. 1.8) and oblique ultrastructure (Janofske and Karwath in Karwath 2000; Streng et al. 2004a), whereas Calciodinellum has a mesoepicystal archeopyle (sensu Streng et al., 2004a) and tangential ultrastructure. The two taxa transferred by Fensome and Williams (2004) accord with the morphology of Calciodinellum rather than Pernambugia: hence the new combinations below.
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