NESTING BEHAVIOR IN TRICHILLUM HAROLD, 1868 AND RELATED GENERA (COLEOPTERA: SCARABAEIDAE: SCARABAEINAE: ATEUCHINI: SCATIMINA): A PRIMITIVE PROCESS OR A LOSS OF NIDIFICATION?

All available information, both published and unpublished, on the nesting behavior of Trichillum Harold and other Scatimina with fused abdominal sternites, including laboratory breeding results for Trichillum, is presented. These genera exhibit none of the behavioral traits that are characteristic of the Scarabacinae. In fact, their resource utilization is the simplest known to date for this subfamily, and is similar to that of the majority of the Aphodiini (Scarabaeidae: Aphodiinae). We discuss whether these genera exhibit ail ancestral nesting behavior, or have lost nesting behavior. The phylogenetic relationships of these taxa should be the clue to understanding if the behavior analyzed here is a primitive or a derived one, and all evidence points to a loss of the original nesting behavior.