Revisionary studies of Nearctic Dixidae: the Dixa rudis and D. fusca species groups
Moulton, J. K.  2017.  Annual Meeting of the Entomological Society of America. November 5–8, Denver, CO..

INTRODUCTION: The Dixa rudis and D. fusca species groups, the former having a classic Pacific “ring of fire” distribution and the latter entirely restricted to the Nearctic Region, are defined and revised. This revision treats all Nearctic dixid species with adults having a solid brown or indistinctly striped scutum, setose katepisternum, males with prominent distal subepandrial sclerite lobe, and larvae possessing two abdominal prolegs. Males among and between these groups can be distinguished from one another and from those of Meringodixa by subtle differences in several features of the terminalia. METHODS: Adults were obtained by aspiration, sweeping, light and Malaise trapping, rearing, and via loans from colleagues and institutions. Specimens were preserved into 95% ethanol to facilitate DNA fingerprinting used to confirm identification and association of females, or rarely larvae. Terminalia were cleared in hot lactic acid and kept in glycerin to facilitate microscopic examination. RESULTS/CONCLUSIONS: The D. rudis group includes 11 Nearctic members: D. distincta, D. johannseni, D. rudis, plus 8 new to science. Included within the D. fusca group are 16 species: D. appalachiensis, D. blax, D. calciphala, D. elkmontensis, D. fluvica, D. fusca, D. garretti, D. inextricata, D. pullogruma, D. repanda, D. rhathyme, D. ubiquita, D. vockerothi, plus 3 new to science. New synonymies are proposed for D. adleri (= D. fluvica) and D. brevis (= D. blax), and D. garretti is resurrected from synonymy with D. rhathyme. Adults of all 27 species are re-described or described, distributional and ecological data are summarized, and a dichotomous key to males is presented.