Nests and brood balls of two South American species of Sulcophanaeus Olsoufieff, 1924 (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini)

Abstract

Nests of Sulcophanaeus menelas (Laporte) and Sulcophanaeus imperator (Chevrolat) are composed of single or branched, vertical to horizontal tunnels, empty or partially filled with dung, and at most one nesting chamber bearing a brood ball. Horizontal, branched nests were found made only by S. imperator, whereas branched nests of S. menelas were vertical. Brood balls of S. menelas are drop-shaped with a conical upper pole and a plug of dung fibers. The egg chamber, inside the provisions, is lined with organic matter, probably adult feces. Brood balls of S. imperator are pearshaped, showing a protuberance composed of soil material, which contains the upper half of the egg chamber. The lower half is located in the provisions. The egg chamber has an upper pore and its wall, relatively thick, is made of soil material and dung fibers, like the external wall. These observations are analyzed considering previous reports, behavioral plasticity, adaptations to different environmental conditions, and phylogeny. Brood balls of S. imperator are similar to the ichnofossil Coprinisphaera kheprii Laza from the Cenozoic of Argentina.