Abstract

CUSMINSKY, Gabriela; GARCIA, Adriana  and  HERBST, Rafael. Ostracods (Crustacea, Ostracoda) and charophytes (Chlorophyta, Charales) from the Desencuentro formation (Upper Miocene), La Rioja province, Argentina. Ameghiniana [online]. 2006, vol.43, n.2, pp.327-338. ISSN 1851-8044.

Ostracods and charophytes from the Desencuentro Formation (La Rioja Province, Argentina) are described and illustrated. The association has low diversity with six ostracod taxa: Eucypris sp., Darwinula sp., Cyamocytheridea sp., Cyprideis salebrosa hartmanni Ramírez, Limnocythere aff. L. reticulata Sharpe, Limnocythere sp. and two charophytes: Chara zeylanica s. l. Klein ex Willdenow and Chara musacchioi García sp. nov. The availability of twenty well preserved gyrogonites of Chara musacchioi sp. nov. allowed to observe the intra-populational morphological variability, to relate the new species with the extant Chara hornemannii Wallman, and to conclude that it is a new species. The assemblage indicates a calm aquatic environment with oligohaline to mesohaline water, with a possible input of fresher water, in a tropical to subtropical area, with mean temperature of about 15-20°C.

Keywords : Ostracoda; Charales; Palaeolimnology; Upper Miocene; Argentina.