Overcoming Darwinian and Eltonian shortfalls of biodiversity knowledge in the tropical termite assassins

A thorough understanding of biodiversity depends on much more than just taxonomy. Beyond the description of all Earth’s species, complete knowledge of other aspects of biodiversity such as evolutionary relationships (Darwinian) or biotic interactions (Eltonian) may be even less achievable. We tackled these challenges for a group of assassin bugs, the pantropical Salyavatinae (Hemiptera: Reduviidae; 17 genera, 107 species) which contains members with enigmatic morphology and specialized predatory behaviors. All Salyavatinae are suspected specialist termite predators; however, preexisting observations are limited to seven species and relationships among taxa are unknown. Prior analyses indicate that Salyavatinae may be paraphyletic with respect to another subfamily, Sphaeridopinae, also hypothesized to feed on termites. A molecular phylogeny (7 loci) of these putative termite assassins (28 species, 9 genera) is constructed and used in a dating analysis to shed light on the origin of this clade. DNA extracted from gut contents of 50 individuals was assayed using PCR with taxon-specific primers. Molecular assays, along with recent photographs and observations, provide substantial evidence that this clade feeds specifically upon termites, documenting 28 new individual associations. Our phylogeny supports a sister group relationship of the Neotropical genus Salyavata with Sphaeridopinae. Termite association data mapped upon our phylogeny provide evidence of previously unknown prey conservatism among this group, potentially one of the most diverse monophyletic groups of specialist termite predators, and demonstrates the explanatory power of combining these two elusive facets of biodiversity.