Morphological and Genetic Reappraisal of theOriusFauna of the Western United States (Hemiptera: Heteroptera: Anthocoridae)

Abstract

Examination of minute pirate bugs, Orius spp. (Hemiptera: Heteroptera: Anthocoridae), from a broad geographic range in the western United States prompted a reappraisal of the taxonomic composition of the fauna native to the western United States and Canada. Current syntheses and catalogs list three species of Orius native to this region. In a previous study, we showed how geographic variation in external traits of one of these species, Orius diespeter Herring, 1966, had led to mistakes in identification of species within this complex. More extensive collecting efforts have now led to the discovery of specimens having traits not fully consistent with descriptions of any described species. We provisionally categorized these unresolved specimens into one of eight phenotypic groups based upon combinations of body size, visual appearance of genitalia, association with specific plant taxa, and geographic source. Genitalia from 382 specimens were then measured to determine whether phenotypic groupings were confirmed by statistical analysis of genitalic morphology. Principal components analysis showed that size and shape of the male’s paramere differed among phenotypes. The paramere of unresolved specimens often diverged from the paramere of described species. Length of the female’s copulatory tube differed between several of the unresolved phenotypes and described species. Analysis of DNA sequences showed that five of the eight phenotypes diverged genetically from other phenotypes and from described species. DNA sequence data did not separate two described species ( Orius tristicolor (White, 1879) and Orius harpocrates Herring, 1966), suggesting that these two species are a single species. The combined morphological and genetic evidence indicates that the Orius fauna of the western United States is composed of a mix of two described species and possibly five undescribed cryptic species. We summarize the known distributions of described and cryptic undescribed species, and discuss the implications of our work for the biological control community.