The Paleogene dinoflagellate cyst genera Enneadocysta: new observations from offshore eastern Canada and the Southern Hemisphere.

FENSOME, R.A., GUERSTEIN, G.R. AND WILLIAMS, G.L.

Bahía Blanca, Universidad Nacional del Sur

Simposio; XIII Simposio Argentino de Paleobotánica y Palinología; 2006

Enneadocysta is a biostratigraphically important Paleogene dinoflagellate cyst genus.  Its original interpretation as a partiform type (and thus belonging to the suborder Cladopyxiineae) was based on the presence of two antapical processes.  Another Paleogene genus, Areosphaeridium, is similar, at least superficially, to Enneadocysta, but has a single antapical process, placing it in the sexiform suborder Gonyaulacineae.  The morphology of a new species of Enneadocysta from offshore eastern Canada shows that the two antapical processes of the genus are penitabular, not mesotabular, and indicates that the genus is a gonyaulacinean, not a cladopyxiinean.  This new interpretation, as well as new material from southern Argentina and the Tasman Sea confirms the generic assignment and interpretation of one important Southern Hemisphere species of Enneadocysta.  A new genus and species from offshore eastern Canada is intermediate in morphology between Enneadocysta and Cleistosphaeridium and strongly suggests an assignment for these genera to the gonyaulacinean family Areoligeraceae.