Evolution of contrasting defensive strategies within the North American Asidini (Coleoptera: Tenebrionidae)

The tribe Asidini, unlike many darkling beetle groups, lacks defensive glands. Instead morphological and behavioral adaptations have arisen within the tribe, presumably to limit predation. The majority of asidine species worldwide are somewhat cryptic in coloration and sculpturing, but two distinct adaptive strategies have evolved within the North American Asidini that are unique or uncommon within the tribe. One is extreme crypsis, including the production of adhesive chemicals to coat themselves with soil or debris and thanatosis or “playing dead”. The other is Batesian mimicry, specifically of the widespread chemically defended tenebrionid genus Eleodes. A preliminary phylogeny indicates that extreme crypsis evolved once within the North American asidines while mimetic morphology and behavior have evolved at least twice.