Abstract
This paper describes Pseudosinella altamirensis sp. nov. from the Altamira Caves, municipal district of Santillana del Mar (Cantabria, Spain), and five other caves near the coast of Cantabria (northern Spain). Its taxonomic position is discussed and differences and similarities among morphologically and geographically close species are highlighted. The new species can be identified by its five eyes, the basal and small inner paired teeth on the claw, and the length of the uncrenulated part of the distal dens.