Octahedronoides tethysianus n.gen., n.sp., enigmatic clusters of microspheres at the Jurassic-Cretaceous transition

Abstract

In the literature, numerous accounts exist of microspheres scattered in the pelagic environments of the Tethys realm at the Jurassic-Cretaceous transition. These microspheres are commonly associated with genera such as Cadosina, Colomisphaera, or Stomiosphaera, and attributed to calcareous dinocysts. On the other hand, there are few records of the microsphere, initially described as Cadosina minuta BORZA, 1980, which are arranged in small clusters, likely comprising six cells. This distinctive grouping and its architecture preclude attribution to the calcareous dinocysts. A new genus and a new species (as Octahedronoides tethysianus n.gen., n.sp.) are introduced to define these clusters of leiospheres, which are here reascribed to the acritarchs.