The subgenus Platyderides was erected to include those species of Aphodius in which the side pronotal margins are explanate. The group is better known as Horn's series I-a. The genus Aphodius does not lend itself well to subdivision, consequently Platyderides is not sharply defined. The only character of key value in defining the group is the explanate pronotal side margin, but this character is lacking in insolitus and feebly developed in several others. The species are usually strongly shining and medium sized or large for the genus.