A new interstitial species of Gammarella (Amphipoda, Gammaridea) from the western Mediterranean Sea

A new species of Gammarella Bate, 1857 is described from shallow water, inhabiting the interstitial system in soft bottoms of the Chafarinas Archipelago (western Mediterranean, N. Africa). The relationships of Gammarella with the genera Nuuanu and Cottesloe are briefly discussed. Numerical taxonomie methods are utilized to differentiate between the morphologically related species and the intermediate species. In a table the principal differentiating characters of Gammarella species are presented. Gammarella garciai n. sp. is characterized by its intermediate position between Gammarella, Nuuanu and Cottesloe, showing an intergradation of characters. Gammarella garciai n. sp. and G. merringannee show ecologically intermediate characters between the larger species, probably nestling, with preference for lightless environments, and the smaller species. The group of smaller species, with eyes poorly developed or absent, show interstitial preferences. A map of the world distribution and a key to the 11 known Gammarella species are presented.