Eyes of the Deep-sea Floor: The Integrative Taxonomy of the Foraminiferal Genus Vanhoeffenella

Vanhoeffenella is a common deep-sea monothalamous foraminifer, some species of which have a unique eye-like test morphology. Owing to its world-wide distribution, it has been recorded numerous times since the “heroic age” of the deep-sea exploration in the early 20th century. So far, only 4 species have been described, and no attempts have been made to estimate the real diversity of this peculiar genus. Over the last fifteen years, we have collected specimens of Vanhoeffenella from various deep-sea areas, providing the basis for an integrative taxonomy and biogeography of this genus. Here, we clarify the phylogenetic position of Vanhoeffenella and give an account of its diversity in the Atlantic, Arctic and Southern Oceans (the Weddell Sea) as revealed by genetic marker (SSU rDNA) and morphology. Our study shows that Vanhoeffenella branches within Clade F of monothalamids and incorporates at least 10 putative species. Some could be distinguished by either morphological or molecular features, but only the integrative taxonomic approach provides a robust way to assess their diversity. We examine the new material of the type species (V. gaussi Rhumbler), redescribe the poorly-known V. oculus Earland and describe formally a fifth species, V. dilatata sp. nov.