Cytological studies were made on larvae of Gigantodax marginalis, G. chilensis, G. fulvescens and Cnesia dissimilis from four creeks in Lanin National Park, Neuquen province, Argentina. Chromosome maps and idiograms of these species are presented. The following inversions were observed: G. marginalis: IL-1 (X-linked inversion), IL-2 (Y-linked inversion), IIS-1.2, IIL-1, IIIL-4,5; G. chilensis: IL-4 (X-linked inversion), IIS-1.2, IIIL-4,5; G. fulvescens:IL-1 (X-linked inversion), IL-3 (Y-linked inversion), IIS-1.2, IIL-1, IIIL-4,5; C. dissimilis: IL-1, IL-5, IIIL-1. Karyological information was used to construct a cladogram and Cnesia sp. Was found to show close resemblance to the three Gigantodax spp.