A NEW INTERSTITIAL SPECIES OF GAMMARELLA (AMPHIPODA, GAMMARIDEA) FROMTHE 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 taxonomic methods are utilized to differentiate between the morphologically related species and the intermediate species. In a ta ble the principal differentiating characters of Gammarella species are presented. Gammarella garciai n. sp. is characterized by its intermed iate position between Gammarella, Nuuanu and Cottesloe, showing an int ergradation of characters. Gammarella garciai n. sp. and G. merringann ee show ecologically intermediate characters between the larger specie s, probably nestling, with preference for lightless environments, and the smaller species. The group of smaller species, with eyes poorly de veloped or absent, show interstitial preferences. A map of the world d istribution and a key to the 11 known Gammarella species are presented .