Caiza Roewer, 1925, is considered a junior subjective synonym of Pectenobunus Roewer, 1910, and its type species Caiza colliculosa Roewer, 1925 is newly combined as Pectenobunus colliculosus. The genus Pectenobunus should now include three species distributed in the Southern Cone of South America and Bolivia. Emended diagnoses are given for Pectenobunus and its three species. The diagnostic combination of characters of the genus is discussed, and compared with species with similar morphology found in the southern South American cone. A key for identification of the species included in Pectenobunus is provided. Characters most valuable to systematics penis, abdominal scute, and color pattern are illustrated and described for Pectenobunus colliculosus for the first time.