The holotype of Cecoditha parva Mello-Leitão 1939, from Chubut Province, Argentina, is redescribed and shown to be a typical member of the genus Austrochthonius Chamberlin 1929. The monotypic genus Cecoditha Mello-Leitão 1939 is therefore a junior subjective synonym of Austrochthonius, while the subfamily Cecodithinae Chamberlin & Chamberlin 1945 (Tridenchthoniidae) is a junior subjective synonym of Chthoniinae Daday 1888 (Chthoniidae).