A new species of Bathynomus A. Milne-Edwards, 1879 (Malacostraca: Peracarida: Isopoda: Cirolanidae) from the upper Miocene of the Guadalquivir Basin (Spain)

Abstract

Today representatives of the giant cirolanid isopods of the genus Bathynomus inhabit tropical to warm-temperate waters of the West Atlantic and the Indo-West Pacific. In not so distant geological past, however, the genus was present also in the Mediterranean, as documented by numerous fossils from the Plio–Pleistocene of Italy. Herein, a somewhat older occurrence of the genus is reported, from the North-East Atlantic. Based on a single posterior moult from the upper Miocene (Tortonian) of southwestern Spain, a new species is described. Bathynomus civisi sp. nov. differs from its congeners by both uropod rami having the obtuse distolateral corner produced as a distinct tip and a wider gap between the second and third side distal spines than between others. The new species is so far known only from the type locality in close vicinity of Arroyo Trujillo, in the municipality of Cantillana (Seville, Spain), where the marls of the Écija Formation are exposed. At the time of deposition of these marls, the area represented a part of the Norbetic Strait, a corridor connecting the North-East Atlantic with the Mediterranean. The new occurrence reported herein further supports the environmental preferences of the genus throughout its geological past for deep-marine settings.