The genetic diversity, morphology and biogeography of Ammonia specimens was investigated across the Northeast (NE) Atlantic margins, to enhance the regional (palaeo)ecological studies based on this genus. Living specimens were collected from 22 sampling locations ranging from Shetland to Portugal to determine the distribution of Ammonia genetic types across the NE Atlantic shelf biomes. We successfully imaged (via scanning electron microscopy, SEM) and genotyped 378 Ammonia specimens, based on the small subunit (SSU) rRNA gene, linking morphology to genetic type. Phylogenetic analyses enabled identification of seven genetic types and subtypes inhabiting the NE Atlantic margins. Where possible, we linked SSU genetic types to the established ...