Ecology and taxonomy of the genus Eurydice (Isopoda: Cirolanidae) from sand beaches on the Iberian Peninsula

Quantitative sampling for the genus Eurydice (Isopoda: Cirolanidae) was conducted on 25 sand beach sites along the Atlantic coast of the Iberian Peninsula. Five species were recorded intertidally: Eurydice affinis, E. pulchra, E. naylori sp. nov., E. lusitaniensis sp. nov. and E. spinigera. Physical data collected were used to construct an index of exposure to rank each site. The distribution of intertidal Eurydice sp. is described in relation to exposure to wave action and to tidal level. Peak abundance of E. affinis, E. pulchra and E. naylori occurred most frequently between mean high water neap (MHWN) and mean tide level (MTL). Whilst E. affinis occurred over a wide range of exposure, E. naylori exhibited a marked preference for exposed sites and E. pulchra was only recorded from sheltered and semi-exposed sites. Surf plankton collections revealed the presence of E. lusitaniensis, but as only two specimens were collected, its ecology remains unknown. The zoogeographical distribution of the genus on North Atlantic and Mediterranean coasts is briefly reviewed.