During the Amsterdam Expedition to the Dominican Republic five samples containing three species of anthurid isopods, two of them new to science, were collected, viz. Cyathura (Stygocyathura) salpiscinalis Botosarieanu & Stock, 1982; C. (S.) broodbakkeri n. sp.; and C. (C.) tridentata n. sp. The latter is the first hypogean representative of Cyathura s. str. from the Caribbean. All the known Hispaniolan species, C. (S.) motasi Botosaneanu & Stock, 1982, excepted, are found in a limited area that during the Tertiary was covered by an inland sea. Here a rapid speciation occurred in two isolated lakes that were cut off from the sea, and from each other, as a result of uplift in this valley.