New cave-dwelling amphipods (Lysianassidae, Hadziidae) from the Dominican Republic (Hispaniola)

Two new stygobiont amphipods are described from anchialine caves located in the Jaragua region (Pedernales Prov., Dominican Republic, Hispaniola). Ottenwalderia kymbalion gen. et sp. nov. is the first lysianassoid known to have penetrated into completely fresh waters, and the fourth colonizing hypogean habitats. Bahadzia jaraguensis sp. nov. is the second representative of this West Indian thalasso-stygobiont genus to be reported from fresh waters; it exhibits the most troglomorphic aspect (i.e. elongation of first antennae and sixth pereiopods) recorded for the genus. Its diagnosis is complemented with a key to the species of the genus Bahadzia. The in situ swimming behaviour of both taxa is briefly described. It is postulated that both amphipods share a rather recent, Plio-Pleistocene marine origin, having invaded passively the continental waters in the way described by the so-called Regression model.