How environmental change affects a species' phenotype is crucial for taxonomy and biodiversity assessments and for their application as paleoecological indicators. Morphometric data of a Neotropical ostracod species, as well as several climatic and hydrochemical variables, were used to investigate the link between morphology and environmental conditions. Temperature seasonality, annual precipitation, and chloride and sulphate concentrations were identified as drivers for ostracod ecophenotypy.