Hippolyte longiallex n. sp. is described after specimens from Principe and São Tomé islands (West Africa). This species, which is the smallest of the genus Hippolyte Leach, 1814, is very similar to the West Indian species H. nicholsoni Chace, 1972. In H. longiallex n. sp., the third to fifth pereiopods have longer dactyli with longer spines on the flexor border than in H. nicholsoni. Both H. longiallex n. sp. and H. nicholsoni are gorgonian associates. Hippolyte catagrapha n. sp. is described after specimens from South Africa (False Bay). It is very similar to the European species Hippolyte leptometrae Ledoyer, 1969, both species being crinoid associates. Hippolyte leptometrae has two dorsal teeth: one median and one subdistal. Hippolyte catagrapha n. sp. has only one median dorsal tooth. Hippolyte leptometrae is recorded for the second time in the Bay of Biscay and illustrations of an Atlantic specimen are given for the first time. A putative new species close to H. varians Leach, 1814 and H. kraussiana (Stimpson, 1860) is recorded from Principe and São Tomé islands but it is not named because the available material is insufficient. Its rostrum has three dorsal teeth and the sixth segment of its pleon is very slender. Hippolyte varians is recorded for the first time in the area of Tromsø, northern Norway. An identification key is provided for all Hippolyte species from the Atlantic Ocean, the Mediterranean Sea and neighbouring areas.
Crustacea, Decapoda, Caridea, Hippolyte, identification key, Atlantic, commensal, gorgonian, crinoid, new species.