A new species of the subterranean amphipod genus \u3cem\u3eAllocrangonyx\u3c/em\u3e (Gammaridae), with a redescription of the genus and remarks on its zoogeography

The systematics of the North American, subterranean amphipod genus Allocrangonyx are revised and two species are recognized - A. pellucidus (Mackin) and A. hubrichti, new species. Allocrangonyx is critically compared with the European genus Niphargus and several endemic North American genera of the Crangonyx group. Because of its unique morphological position, Allocrangonyx is removed from the Crangonyx group and placed in the newly designated AlIocrangonyx group. Some factors believed to have influenced speciation within the genus are discussed in some detail