Flies of Rhagoletis (Diptera: Tephritidae) are economically important fruit pests (infesting specialty fruit crops including apples, blueberries and cherries), which also serve as models for studying modes of speciation and coevolutionary relationships with their hymenopteran parasitoids. There are new species within the genus which have not been previously formally described. One of these species is within the tabellaria species group. I describe the morphology of Rhagoletis bushi Hulbert & Smith, its geographic distribution, host association, phylogenetic relationships, and identify an associated species of parasitoid wasp. The new species infests the fruit of buffaloberry (Shepherdia argentea) in the Northern Great Plains of North America. There is a suite of morphological characters, and a unique host plant association, that are diagnostic of R. bushi. Further evidence for the validity of R. bushi and its placement within the tabellaria species group comes from DNA sequence data from multiple genetic loci. The phylogenetic relationships among Rhagoletis species groups remain unresolved despite analyses based on morphology, allozymes, and mitochondrial DNA. Most Nearctic Rhagoletis belong to one of five species groups (pomonella, tabellaria, cingulata, suavis , and ribicola groups), with two unplaced species (R. fausta and R. juniperina), all of which appear to be part of a larger monophyletic group that also includes some Palearctic taxa. Regarding the overall phylogeny of the genus, my goals were to 1) resolve phylogenetic relationships using mitochondrial (COI) and nuclear (28S, CAD, period, AATS) DNA sequences, and 2) to identify the monophyletic group containing these Nearctic species. Using Bayesian analysis of a combined dataset with 4399 aligned nucleotides, I inferred a well-supported monophyletic group containing the five Nearctic Rhagoletis species groups, plus R. fausta, R. juniperina, and two Palearctic species: R. batava and R. flavigenualis. Within this larger monophyletic assemblage, the five Nearctic species groups together are monophyletic as are four of the five individual species groups (not ribicola). Palearctic and Neotropical Rhagoletis were resolved into well-supported clades of taxa often sharing closely related host plants. A well-resolved phylogeny of Rhagoletis is a valuable tool for future work addressing questions pertaining to how history, geography and ecology have shaped the phylogenetic patterns we observe in the genus. It is often claimed that systematic biology is fundamental to all other areas of biology. I critically evaluate the acceptance of this claim by entomologists critically as it relates to the field of entomology. I also critically describe the justification and valuations for systematic biology using the framework of Boltanski and Thevenot's realms of worth and the philosophical framework for justification using virtues, desserts and outcomes. In order to accomplish these purposes, I critically analyze and review relevant entomological literature and interview practitioners of entomology and insect systematic biology. I find justification for systematic biology overwhelming takes the form of appeals to utilitarianism (both internally and externally focused) and are most relevant in the Industrial World. Additionally, some justifications given also pertain to the Civic World and to virtue. Evaluation of justification in systematic biology is important, especially as our globe becomes increasingly ecologically and politically unstable.
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