Geographical location of Altamira Caves (Cantabria, Spain). A location and ground plan of the Altamira Caves and its museum B location of the Pseudosinella altamirensis sp. nov. sampling sites along Altamira Cave (August 2000): (1) areas where soil contained mouldy rat or bat faeces; (2) areas where soil contained a rat cadaver (Rattus rattus); (3) areas where soil contained a bat cadaver (Rhinolophus hipossideros); (4) areas where walls had insect cadavers with visible fungal; (5) areas where water drips or flows towards the cave (hygropetric habitats); (6) areas where water had flooded the surface with small rim stone dams or gours; (7) areas with high clay soil content in the water; (8) areas of continuous monitoring of radon. Plan of the caves with its location courtesy of the National Museum and Research Centre of Altamira.