The Paussus (Carabidae: Paussinae) of Madagascar: An explosive radiation of myrmecophilous beetles

Members of the carabid subfamily Paussinae (flanged bombardier beetles) are famous for their explosive defensive chemistry and symbiotic life histories with ants. Among paussines, the genus Paussus is most diverse, with ~340 described species distributed in the tropical regions of the Old World. The species diversity within this charismatic genus is reflected in an astounding breadth of morphological diversity.

Phylogenetic relationships within Paussus have been obscured by extreme anatomical adaptations and convergences resulting from myrmecophilous life styles. Contrary to historical concepts of relatedness, molecular data demonstrate that all of the species of Paussus endemic to Madagascar form a monophyletic group that appears to be a product of an explosive radiation that began only 2-5 mya (Moore, in prep.). Furthermore, recent large-scale collecting efforts within Madagascar by the California Academy of Sciences reveal a striking amount of undescribed Paussus species diversity.

We investigate the evolutionary history and species diversity of the Malagasy Paussus clade using molecular phylogenetics coupled with standard morphological techniques. In light of our phylogenetic results, we additionally comment on the potential use of the Malagasy Paussus clade as model system to explore patterns of adaptive radiation.