A cladistic analysis of <i>Simulium (Trichodagmia) sensu</i> Crosskey and Howard, using 34 morphological characters of larvae (6 characters), pupa (5) and adults (23), yields nine most parsimonious trees under equal weights (length 101 steps CI 0.49 RI 0.73). Successive weighting based on the maximal rescaled consistency index preferred one of the nine (31.37 steps CI 0.62 RI 0.87 total fit<SUB>con3</SUB> = 235.8), which was also one of two trees found under implicit weights with concavity values of 3-6. The cladogram justifies the recognition of two subgenera. <i>Simulium (Trichodagmia) sensu stricto</i> (containing <i>S. muiscorum, sumapazense, S. wygodzinskyorum, S. nigrimanum, S. chalcocoma, S. huairayacu</i> and <i>S. lahillei</i>) is supported by the branchial tip sclerotization and the presence of cibarial teeth, larval body tegument covered with lanceolate hairs, female with simple claw, and gonapophysis size. <i>Simulium (Thyrsopelma)</i> (containing <i>S. scutistriatum, S. hirtipupa, S. orbitale, S. guianense, S. perplexum</i> and <i>S. itaunense</i>) is supported by the hypostomial teeth.Facultad de Ciencias Naturales y Museo