Madagascar’s millipede assassin bugs (Hemiptera: Reduviidae: Ectrichodiinae): taxonomy, phylogenetics, and sexual dimorphism

Madagascar is one of the major biodiversity hotspots that is characterized by high species richness coupled with an extreme loss of primary habitat. To assess the impact of habitat loss and invasive species, and to improve the inadequate knowledge of species diversity, taxonomic surveys of the Malagasy biota, in particular, of the understudied arthropod groups are of critical importance. Millipede assassin bugs in the subfamily Ectrichodiinae (Hemiptera: Reduviidae) are a diverse group (>600 species) of specialized millipede predators, with only 9 species documented from Madagascar. Ectrichodiinae are unusual among Reduviidae in that species frequently display strong sexual dimorphism, rendering association of males and females difficult. Material from an arthropod survey conducted by the California Academy of Sciences (CAS) provided a unique opportunity to examine >1,400 specimens of Malagasy ectrichodiines and explore delimitation of new taxa based on male specimens. The results of this study indicate that the Malagasy ectrichodiine fauna comprises more than 40 species. 90 morphological characters were coded for 55 taxa, and phylogenetic analyses were performed to establish generic limits for these taxa. To associate females with males, ~430 bp of DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene were analyzed. Results show that phylogenetics is an important tool to inform decision-making in taxonomy and that a small amount of sequence data can impact our ability to match dimorphic sexes in Reduviidae.