A study of the monophyly and phylogenetic relationships among the Gigantodax species-groups was conducted using all Gigantodax species and six outgroups. This analysis was conducted using 71 characters, 58 of them morphological characters derived from 66 species, and 13 of them cytological characters from 11 species. We conducted two analyses under linear parsimony and implied weights. To define the best concavity value we used the frequency index. The value that recovered the most of the groups was linear parsimony search. We obtained 2037 equally parsimonious trees of 277 steps (CI=0.37 RI=0.65). The second value to recover most of the groups was implied weight search with the concavity value of one. Only the igniculus and minor groups were recovered by both analyses (linear parsimony and implied weights K=1). Under linear parsimony the phylogenetic analysis recovered two species groups (igniculus and cormonsi). The remaining four groups (“brophyi”, “cilicinus”, “minor”, and “wrighti”) are non-monophyletic. Based on the cladogram we suggest the following species groups: igniculus (igniculus group), cormonsi (cormonsi group), minor (containing “minor” + “multifilis”), brophyi (G. antarcticus, G. brophyi, G. femineus, G. rufidulus, and G. trifidus), shannoni (containing G. bettyae, G. incomitatus, G. mariobordai, G. pennipunctus, G. septenarius, and G. shannoni), and rufescens (containing G. aquamarensis, G. arrarteorum, G. basinflatus, G. cervicornis, G. cilicinus, G. clandestinus, G. corniculatus, G. cypellus, G. dryadicaudicis, G. herreri, G. horcotiani, G. impossibilis, G. incapucara, G. nasutus, G. rufescens, and G. wrighti). Some species, previously assigned to “cilicinus”, “wrighti”, and “brophyi” groups are kept as inquerandae.