The Pupation Chamber of Dung Beetles (Coleoptera: Scarabaeidae: Scarabaeinae)

Abstract

Third instars of the Scarabaeinae species Sulcophanaeus menelas (Laporte), Sulcophanaeus imperator (Chevrolat), Sulcophanaeus batesi (Harold) (all Phanaeini), Ontherus sulcator (F.) (Dichotomiini), and Malagoniella argentina (Gillet) (Canthonini) construct pupation chambers inside brood balls. Similar chambers are constructed by larvae of Anomiopsoides biloba (Burmeister) (Eucraniini) inside nests. The wall of these pupation chambers is a helicoid composed of whorls showing transverse rows of imbricate pellets. When this character is optimized on a simplified cladogram of Scarabaeinae, the helicoidal wall seems to be a synapomorphic character for the clade that includes Phanaeini, Eucraniini, Neotropical Canthonini, and some species of Dichotomiini. It may be predicted that species of other tribes belonging to this clade (Scarabaeini, Gymnopleurini, Eurysternini, and some Coprini) would construct similar pupation chamber walls. In addition, the presence of two other types of pellet arrangements in the pupation chamber wall in species of Liatongus Reitter (Oniticellini) and Heliocopris Hope (Dichotomiini), which are grouped in the other main clade of the subfamily, suggests that the behavior of arranging pellets in rows in the pupation chamber wall appeared in the node that defines Scarabaeinae.