Re-study of some dinoflagellate cysts from the Oligocene and Miocene of Germany

William A S Sarjeant

doi:10.1144/jm.3.2.73

Abstract

Abstract. The type material of six dinoflagellate cyst species from the Late Oligocene to Middle Miocene of northwest Germany, described originally by Gerlach (1961), is reillustrated and redescribed. It is shown to include representatives of nine species. Areosphaeridium (ex: Baltisphaeridium) pectiniforme is found to be a senior synonym of Areosphaeridium multicornutum Eaton. Systematophora placacantha is considered to be a senior synonym of Cleistosphaeridium (ex: Baltisphaeridium) panniforme (Gerlach). The new combination Rhynchodiniopsis tenuitabulata (Gerlarch) is proposed. Revised diagnoses for these three species and for Leptodinium membranigerum (Gerlach), Achomosphaera triangulata (Gerlach) and Lejeunecysta hyalina (Gerlach) are proposed. The morphology of a form described here for the first time, and tentatively attributed to Phthanoperidinium, is considered perhaps to imply a separate origin for the Phthanoperidiniaceae: for that reason familial, rather than tribal, rank is preferred for that group. The stratigraphical ranges of the nine species here recognised and of two others of Gerlach’s species redescribed in earlier papers are detailed; elimination of misattributed forms means that these ranges are shorter than the published literature suggests.

Highlights

The history of early studiesof Oligocene and Miocene dinoflagellate cysts has been summarised in an earlier paper (Sarjeant, 1983)
A misunderstanding concerning the morphology of her fourth genus, Emsfundiu, caused it to be formally abandoned for a while; recently it has been likewise reinstated under a revised definition (Benedek & Sarjeant, 1981)
Even when Eaton first proposed his species Areosphaeridium multicornutum, he was aware that it might prove to be a junior synonym of Gerlach’s Baltisphaeridium pectiniforme, for he commented: “B. pectiniforme has been recorded by two writers, GERLACH (1961) from the Middle Oliogocene of Germany, and BROSIUS (1963) from the Upper Oligocene of Germany

Summary

Introduction

The history of early studiesof Oligocene and Miocene dinoflagellate cysts has been summarised in an earlier paper (Sarjeant, 1983). The holotype was not found; the slide supposed to contain it included a specimen sufficiently similar to it in general form, to have been probably considered referable to this species by Gerlach. The Belgian Eocene specimen illustrated by De Coninck (1968) has an indistinct paratabulation, an ambitus and apical horn of dissimilar character and a much larger archaeopyle; it cannot be referable to this species.

Results

Conclusion