Lower Cretaceous diatoms from ODP Leg 113 Site 693 (Weddell Sea). Part 1: vegetative cells

Abstract

Exceptionally well preserved, nearshore, shallow water diatom assemblages of late Aptian to early Albian age (115-110Ma) are described for Ocean Drilling Program (ODP) Site 693, Dronning Maud Land, Weddell Sea, Antarctica. These assemblages allow insights into phylogenetic relationships during the early evolution of diatoms and the status of diatom evolution by the Early Cretaceous. This contribution focuses on the diatom vegetative cells. A total of 12 new genera, 22 new species, 4 new varieties, and 1 new forma are described, and 5 new combinations are proposed. The genus Gladius Forti and Schulz (1932), including the species G. antiquus, is redescribed and taxa belonging to its later homonym Gladius Schulz (1935) are transferred to the new genus Gladiopsis. The valve characteristics of the taxa are described. One prominent characteristic of the observed late Early Cretaceous diatoms is their chain forming ability. -Authors