Arcticacysta: A new organic-walled dinoflagellate cyst genus from the early Miocene? of the central Arctic Ocean

Abstract

The Cenozoic sedimentary record of the central Arctic Ocean recovered during the Arctic Coring Expedition (ACEX) Integrated Ocean Drilling Program (IODP) Expedition 302 contains a new dinoflagellate cyst genus, Arcticacysta, assignable to the Peridiniales. Two different species are here formally described, Arcticacysta backmanii and A. moraniae gen. et sp. nov. Both species have a combination archeopyle, formed by the loss of several plates. In A. backmanii the archeopyle involves three apical (2’-4’) and three intercalary (1a-3a) plates. In A. moraniae the archeopyle is formed by the loss of four apical (1’-4’) and three intercalary (1a-3a) plates. The species differ in size and in the wall structure. A. backmanii has a microreticulate wall and is relatively large, whereas A. moraniae is smaller and with spinose wall. Their lowest occurrence in the ACEX core lies at the base of subunit 1/5 (core M0002A 46X, 113-114 cm, 198.70 meters composite depth, mcd). Morphologically closely related taxa, potentially re/presenting other species of Arcticacysta, have been previously recovered from the late Oligocene and early Miocene sediments of the Norwegian-Greenland Seas.