Observations on the fossil resting spore morphogenus Peripteropsis gen. nov of the marine diatom genus Chaetoceros (Bacillariophyceae) in the Norwegian Sea

The morphology and taxonomy of the fossil diatom resting spore morphogenus Peripteropsis gen. nov. from the lower Oligocene through middle Miocene sediments of Deep Sea Drilling Project Site 338 in the Norwegian Sea were examined. The new genus Peripteropsis is characterized by elongated processes on the shoulder or centre of its valves and contains four species including one new species and three new combinations: P. tetracladia sp. nov., P. trinodis comb. nov., P. norwegica comb. nov. and P. tetracornusa comb. nov. Peripteropsis tetracladia, the oldest species of the genus, arose in the early Oligocene in the stratigraphic records of the Norwegian Sea, and all Peripteropsis species including the last species, P. tetracornusa, became extinct by the earliest late Miocene. Some species are biostratigraphically useful in the Norwegian Sea and the North Pacific. Moreover, two similar species which may belong to Peripteropsis, 'Periptera' schraderi and 'Periptera' petiolata, are also described.