Round brown spiny dinoflagellate cysts from high latitudes of the Northern Hemisphere have been examined in order to define criteria for their determination during routine counts. The round brown spiny cysts belong to several taxa including the paleontological genera Echinidinium and Islandinium and the biological genera Oblea, Polykrikos, and Protoperidinium. Here, we present a synthesis of descriptions with remarks on the morphology, taxonomy, nomenclature and ecology of cysts from the observations of samples collected in high latitude environments. These observations have led us to establish a practical identification key based on the most distinct morphological features that characterize all specimens. These features exclude the archeopyle, which is rarely observed. Two new cyst types are described from Holocene and Pleistocene sediments of the North Pacific and North Atlantic oceans, respectively. The identification key permits the following to be distinguished: ". Echinidinium aculeatum", Echinidinium delicatum, Echinidinium granulatum, Echinidinium karaense, Echinidinium sleipnerensis, Echinidinium ". transparantum". /zonneveldiae, Islandinium brevispinosum, Islandinium? cezare, and Islandinium minutum, the cysts of Oblea acanthocysta and Polykrikos hartmannii (al. Pheopolykrikos hartmannii), and the new cyst types Echinidinium? sp. A and Echinidinium? sp. B.
Bibliographical noteFunding Information:
We thank the Integrated Ocean Drilling Program (IODP), the international Innovative North Pacific Experiment project (INOPEX), and the MALINA project for providing us with sedimentary samples. NV is grateful to J. Matthiessen (AWI) for help in identifying the cyst Echnidinium sp. A. Financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and from the Fonds de la Recherche sur la Nature et les technologies of Quebec (FQRNT) is acknowledged. We are most grateful to K. Matsuoka for supplying photographs of Polykrikos hartmannii, and to the reviewers for their constructive criticism.
- Determination key
- Round brown spiny cysts