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 referred to 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 loosely but orderly arranged in small clusters, likely comprising six individuals. This singular grouping and its architecture preclude attribution to the calcareous dinocysts. A new genus and a new species are introduced to define these clusters of leiospheres, which are here reascribed to the acritarchs.