Bijdragen tot de Dierkunde, 54 (1): 25-50 — 1984 Amsterdam Expeditions to the West Indian Islands, Report 38. The distribution and zoogeography of freshwater Ostracoda (Crustacea) in the West Indies, with emphasis on species inhabiting wells by Nico W. Broodbakker Institute of Taxonomie Zoology, University of Amsterdam, P.O. Box 20125, 1000 HC Amsterdam, The Netherlands Summary Résumé The distribution of Ostracoda in islands of discute freshwater the On la distribution des Ostracodes dulcicoles sur les the West Indies and part of the Venezuelan mainland is îles des Indes Occidentales et dans certaines zones de discussed. The ostracod fauna of wells and epigean Venezuela. La faune d’Ostracodes des puits et des habitats habitats Some Certaines des is compared. species, e.g. Cypretta spp. are épigés est comparée. espèces (par exemple found often in others significantly more wells, are only espèces de Cypretta) sont trouvées nettement plus souvent found in and dans des d’autres epigean habitats, e.g. Hemicypris spp. Cypris puits, (par exemples Hemicypris spp. et subglobosa. Some species are found significantly more often Cypris subglobosa) sont rencontrées seulement dans des in others to habitats il epigean habitats, e.g. Stenocypris major, seem épigés. Ensuite, y a des espèces nettement plus have and trouvées dans les habitats no preference, e.g. Physocypria affinis Cypridopsis souvent épigés (Stenocypris major tandis spp. par exemple), que d’autres (exemples: Physocypria occurrence of Ostracoda and other faunal semblent avoir de Joint groups affinis et Cypridopsis spp.) ne pas préfé- in wells is studied, especially for hadziid amphipods, which rence. are to on small crustaceans. There On examine la dans les à supposed predate may présence puits, conjointement be some influence ofthe ofhadziid on celle des d’autres presence amphipods Ostracodes, groupes d’animaux, surtout the distribution of some of but this des dont species Ostracoda, Amphipodes Hadziides, on suppose que ce sont could not be tested for most islands and des de Crustacés. statistically prédateurs au dépens petits Il est possi- ble ait certaine de la de species. qu’il y une influence présence ces Some models are discussed. Most biogeographical Amphipodes sur la distribution de certaines espèces ostracods have arrived the islands la des îles seem to at by dispersal. d’Ostracodes, mais, pour plupart et des espèces, No ostracods were found evidence for the ceci n’a être mis évidence bases statisti- representing pas pu en sur des modelof distribution and regression speciation. Practically ques. all seem to be stable and did not evolve species genetically Des modèles biogéographiques différents sont discutés. into true hypogean species. Only in the presumably older La plupart des Ostracodes semblent avoir abordé les îles islands and are Des Hispaniola Cuba, true hypogean species par dispersion. Ostracodes représentant des preuves which seem to have evolved from relict freshwater le “modèle de des found, pour régression” ne sont pas connus ancestors. Caraïbes. Pratiquement toutes les espèces semblent être The results the that Cuba and stables évolué donner de strengthen hypothesis génétiquement et n’ont pas pour been which vraies formes Des Hispaniola have part of a proto-Antillean arc, hypogées. espèces effectivement hypo- has been connected with Yucatan. The fact that no n’ont îles gées été découvertes que sur Hispaniola et Cuba, were found in the Lesser Antilles hypogean species supposées plus anciennes; ces espèces semblent avoir évo- strengthens the hypothesis that these islands have emerged lué à partir d’ancêtres dulcicoles relictes. above the sea level independentlyof the Proto-Antilles and Les résultats obtenus viennent à l’appui de l’hypothèse much later in time. Cuba fait d’un que Hispaniola et ont partie arc proto- Antillais été relié Yucatan. Le fait les Petites ayant au que Antilles n’ont fourni pas des espèces hypogées, est un de de argument en faveur l’hypothèse que l’émergence ces îles été a indépendente et de beaucoup postérieure à celle * Report 37 is published in the same issue of this journal. des Proto-Antilles. Downloaded from Brill.com10/10/2021 01:41:22AM via free access 26 N. W. BROODBAKKER - WEST INDIAN OSTRACODA INTRODUCTION vironment and. adapt to real subterranean conditions. the As In period 1973-1982 the Amsterdam Expe- (2) a place where typical groundwater in the surround- ditions have made groundwater explorations organisms can emerge from and of the and 43 West Indian islands part ing groundwater system, perhaps even Venezuelan mainland. Most of the stations survive. since these form the of To like the in- sampled were wells, way (3) study ecological processes, the subterranean in fluence of restricted access to fauna, especially space, water volume, A number karstified sediments. great of light conditions and other environmental hypogean animals were encountered, but also factors, on the animals, and on the com- animals. The between them. many epigean predominant petition and four As observations what groups were Oligochaeta, Gastropoda (4) a place allowing on when in crustacean taxa: Ostracoda, cyclopoid happens epigean species come con- Copepoda, Amphipoda, and Thermosbaenacea tact with groundwater species. (Stock, 1983a). The ostracods were considered Wells are like islands which can be colonized, to be important because of their abundance and often by epigean, cosmopolitan species. The in whether colonization is constancy hypogean habitats, being present questions are common, in more than halfof the stations sampled, often whether many species succeed, which species in large numbers. They can also be part of the are better colonizers, and whether it is possible food for for the hypogean chain, being a possible prey some species to adapt to groundwater larger hypogean amphipods (Stock, 1983a). environment. Furthermore, the differences in Furthermore, the ostracods were thought to be composition and diversity of populations can be usable for biogeographic modelling, since their studied. distribution It became clear was thought to be influenced that only in the islands and predominantly by dispersal, though some Hispaniola Cuba some species (belonging and Strandesia species could have originated by regression of to the genera Neocypridopsis i) are marine in ancestors or vicariant events. The dif- present, which are possibly some way models and their ferent biogeographic use- adapted to live in groundwater environments, fulness discussed for ostracods in this arti- of their small reduced are on account very size, or cle. The islands harbour other eye pigment. same this it became clear that of all the Caribe- During study most species, belonging to new genus the ostracods encountered belong to epigean candona of the subfamily Candoninae, which is caused the fact in In groups. This by that are stygobiont (Broodbakker, 1983c). a well encountered in in of karstified sediments, as tropical the mainland Venezuela another hypo- and wells with to the new subtropical regions, a large gean species was found, belonging diameter habitat from the Danielocandona represent a differing genus (Broodbakker, 1983c). subterranean surrounding area (Danielopol, Therefore it became inevitable to study most- These wells and 1981). play an important role for ly the aspects (3) (4). Since most species because of the it aquatic life; dry seasons or dry were supposed to be epigean, was necessary climats in these regions, and the lack of other to obtain samples from epigean habitats for aquatic habitats, they provide some ecological comparison. Dr. P. Wagenaar Hummelinck shallow wells about 600 ostracod stability. Only open dry out kindly provided samples of the like during part year, most shallow pools from mostly epigean habitats, sampled and ponds. predominantly in the Lesser Antilles, between A well be in several 1930 and He stations can regarded ways: 1973. sampled many As a where faunal times in different months (1) place some epigean ele- several or even years, ments can survive and the islands perhaps even pene- especially on Curaçao, Bonaire, in the and trate deeper true groundwater en- Aruba St. Martin. Downloaded from Brill.com10/10/2021 01:41:22AM via free access 54 - 1984 27 BIJDRAGEN TOT DE DIERKUNDE, (1) I received Dr. D. L. of the Strandesia Furthermore, through genus (Broodbakker, 1983d, Danielopol 37 ostracod samples from Cuba, 1984a), of the subfamily Candoninae (Brood- from but also few from for the mostly caves, a pools bakker, 1983c), and species Tanycypris and the underflow of running waters, sampled meridana (Furtos, 1936) (Broodbakker, 1984b). Drs. L. Botosaneanu, St. and T. Other like and by Negrea genera, Cypretta Cypridopsis, Orghidan, members of the Cubano-Romanian could not be studied because of the lack of good Biospeleological Expeditions to Cuba, in 1969, descriptions and of time. 1970 and 1973. In the the distribution of all present paper few have been freshwater all islands Only papers published con- ostracods, on sampled, is cerning the freshwater ostracods of the West In- recorded and discussed. The ostracod fauna of dies. Brady (1902) described Cypretta sarsi from wells is discussed and compared with that of St. Thomas, Sharpe (1910) described Chlamydo- epigean habitats. This is done since most of the barbadensis and Brehm wells theca from Barbados, habitats sampled were either or stagnant (1949) described some species, viz. Cypretta epigean habitats. Roughly 50% of the samples taken in both margalefi, Cytheridella ilosvayi Von Daday, 1905 types of habitat, being 360 wells, and Stenocypris major (Baird, 1859), from Cuba. and 182 stagnant epigean habitats, yielded Most other have been described Klie Ostracoda. 37 of which 24 in species by Only caves, Cuba, stations (1933) and Triebel (1961, 1962) from yielded Ostracoda, while only few caves have sampled by Dr. P. Wagenaar Hummelinck. been sampled in the other islands. described some from the effect of the of Margalef (1961) species Furthermore, presence the Venezuelan island of Margarita, which hypogean amphipods, in particular Metani- proved to be already described by Klie (1933) phargus, is studied.