The benthic foraminifer Altamirella biscayana n. gen., n. sp. from the lower Cenomanian of Cantabria, N-Spain: A post-Palaeozoic fusulinan?

The small benthic foraminifera Altamirella biscayana n. gen., n. sp. is described from the lower Cenomanian of the Bielba and Altamira formations (North Cantabrian Basin, Spain). Its trochospirally coiled test combines calcitic dark microgranular and fibro-hyaline layers, an arrangement reminiscent of that observed in Palaeozoic Tetrataxidae Galloway. As in Tetrataxis, these layers are built in successive phases and never form a double-layer sensu stricto. The significance of this distinctive wall structure for taxonomy, phylogeny, dispersal, survival and ecology is discussed. A similar wall organization is also observed in some trochospirally coiled Mesozoic forms such as Mohlerina Bucur, Senowbari-Daryan and Abate and might be inherent to epibenthic taxa developing elevated microhabitats.