Abstract
Occurrences of fossil marine diatom resting spore genus Liradiscus Greville are described from the middle Eocene to middle Miocene samples of Deep Sea Drilling Project Leg 38 Site 338 in the Norwegian Sea. The genus Liradiscus is characterized by a thick frustule sculptured by numerous veins. In this paper, five new taxa (L. cucurbitus, L. castaneus, L. castaneus var. reticulatus, L. caepus and L. nimbus) are described, and their stratigraphical ranges are presented. These species are short-ranging and may be poten- tially useful biostratigraphic markers to improve resolution of diatom biostratigraphy of the Norwegian Sea. Liradiscus castaneus var. castaneus may be evolved from var. reticulatus in the middle part of the Zone NPD 2A (18.4-20.3 Ma). The geologic ranges of L. reticulatus and L. petasus in the Norwegian Sea ( L. reticulatus: early Miocene,L. petasus : late early Oligocene to middle early Miocene) are differentiated from those in the North Pacific (L. reticulatus: middle late Miocene, L. petasus:early late Miocene), suggesting possi- ble the regional environmental differences.
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