Revista Española de Micropaleontología, 37(3), 2005, pp. 431-450 © Instituto Geológico y Minero de España ISSN: 0556-655X 431 RECENT LACUSTRINE OSTRACODS FROM PATAGONIA, ARGENTINA G. C. CUSMINSKY 1 , P. A. PÉREZ 1 , A. SCHWALB 2 AND R. WHATLEY 3 1 CONICET Centro Regional Universitario Bariloche UNC Quintral 1250 S. C. Bariloche 8400, Argentina. gcusmins@crub.uncoma.edu.ar 2 Institut für Umweltgeologie, Technische Universität Braunschweig, Pockelsstrasse 3, D-38106 Braunschweig, Germany. 3 Department of Geology, University of Wales, Aberystwyth, Cardiganshire SY23-3DB U. K. Abstract Fifteen ostracods species from recent lacustrine environments such as springs, seeps, streams, ponds and lakes in Patagonia are described and illustrated. Ten species have been previously descri- bed. One species, Candona sp. cf. C. neglecta Sars, is compared to a previously described taxon while two species, Eucypris cecryphalium sp. nov. and Kapcypridopsis megapodus sp. nov. are described as new species. Limnocythere sp. and Darwinula sp., are left in open nomenclature because of scar- city of material. The fauna, demonstrates clearly the characteristic relationship existing between the physico/chemical and isotopic parameters of the host waters and the ostracod assemblages. Key words: Lacustrine Ostracoda, Recent, Patagonia, Systematics. Resumen Se describen e ilustran quince especies de ostrácodos provenientes de ambientes lacustres recien- tes, tales como vertientes, ojos de agua, corrientes, lagunas y lagos de Patagonia. Diez especies fue- ron descriptas previamente. Una especie, Candona sp. cf. C. neglecta Sars, es comparada con un taxón previamente descripto; mientras que dos especies, Eucypris cecryphalium sp. nov. y Kapcypridopsis megapodus sp. nov., son descriptas como nuevas. Limnocythere sp. y Darwinula sp. han sido dejadas en nomenclatura aperta debido a la escasez del material. La fauna demuestra clara- mente la relación existente entre los parámetros físico-químicos e isotópicos del ambiente con la fauna de ostrácodos presentes. Palabras clave: Ostrácodos lacustres, Reciente, Patagonia, Sistemática. INTRODUCTION Ostracods are microscopic crustaceans with a cal- careous shell and are commonly found in fresh-water and saline aquatic environments. Physico-chemical parameters such as water temperature, pH, salinity, dissolved oxygen and trophicnutrient level (Williams et al., 1993) control their abundance. Therefore, ostra- cods are very useful as palaeoenvironmental indica- tors, especially for the reconstruction of Quaternary non-marine environments (Whatley, 1983, 1988; Forester, 1987; De Decker and Forester, 1988; Lister, 1988; Schwalb, 2003; Schwalb et al., 1994, 1995). This paper presents the ostracod fauna found in 17 sites including springs, seeps, streams, ponds and lakes in Patagonia in the Lago Cardiel area at 48º-49º S and 70º-71º W, and in the Laguna Cari-Laufquen area at 41º-41º30’ S and 68º-69º W (Fig. 1). This study is part of the Patagonian Lake Drilling Project (PATO), a multi-disciplinary, international collaborative effort to recover, for the first time, long palaeoenvironmental and palaeoclimate records from two closed lake basins in Argentina (Schwalb et al., 2002). In 1998 and 1999 pilot studies were carried out with the following objectives: 1) to survey and sample the modern lakes and surrounding environments for