Amsterdam Expeditions to the West Indian Islands, Report 39. Arubolana parvioculata n. sp. (Isopoda, Cirolanidae) from the interstitial of an intermittent river in Jamaica, with notes on A. imula Botosaneanu & Stock and A. Aruboides (Bowman & Iliffe)

Arubolana parvioculata, a new stygobiont species of cirolanid isopod crustaceans, is described from an interstitial habitat near the mouth of an intermittent river, the Rio Secco, Discovery Bay, Jamaica. This is the first subterranean cirolanid from Jamaica. Alltogether, 6 genera of stygobiont cirolanids, with 9 species, are known from 7 islands in the West Indies. The new species has a small and elongate body, which is typical of inhabitants of interstitia. It is also euryhaline. An additional description is given of Arubolana imula Botosaneanu & Stock, 1979, type-species of the genus, based on new specimens from the type-locality. Bermudalana aruboides Bowman & Iliffe, 1983, from caves on the oceanic island Bermuda, is referred to the genus Arubolana. The morphological and ecological differences between the three Arubolana species are pointed out. Some of these differences are usually considered characteristic of distinction on generic level; therefore the three species possibly have to be recognized as members of different subgenera, but on account of our limited knowledge this decision has not been made. It is presumed that the Arubolana species originated from a Metacirolana type of marine ancestor. A general evolutionary scenario for Arubolana is difficult to construct. A. imula is considered a regression element, but A. aruboides and A. parvioculata can be either regression and/or dispersal elements.