Analysis of relevant structures showed that there are three evolutional lineages in Andogyrus. Two have remained in southernmost South America, near the ancestral area of the genus (probably the Antarctic). One lineage has spread northwards and radiated in the Andes. There is a parallel anagenetic evolution of groups of structures which can be related to adaptation to fast-running water. Cladistic analysis according to Hennig (basic splitting) and Camin & Sokal (specific derivation) led to the division of the genus in seven species groups. A key to species is given and six new species group taxa described: A. viscus, A. bos, A. produetus, A. clypealis, A. buculus and A. colombicus subsp. australis.