Evolution and classification of Bibionidae (Diptera: Bibionomorpha)

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Abstract:

The family Bibionidae has a worldwide distribution and includes approximately 700 species in eight extant genera. Recent studies have not produced compelling evidence supporting Bibionidae as a monophyletic group or identified the sister group to bibionids. Therefore, the purpose of this study is to examine the classification and evolution of the family Bibionidae in a cladistic framework. The study has four primary objectives: 1) test the monophyly of the family, 2) determine the sister group of Bibionidae, 3) examine generic and subfamilial relationships within the family, and 4) provide a taxonomic revision of the extant and fossil genera of Bibionidae. Cladistic methodology was employed, and 212 morphological characters were developed from all life stages (adult, pupa, larva, and egg). Characters were coded as binary or multistate and considered equally weighted and unordered. A heuristic search with a multiple random taxon addition sequence was used, and Bremer support values are provided to show relative branch support. A strict consensus of 43 equal-length trees of 1,106 steps indicates that the family Bibionidae is monophyletic and is sister group to Pachyneuridae. All bibionid genera are supported as monophyletic except for Bibio and Bibiodes (monophyly of the latter genus was not examined because only one exemplar was included). Results indicate that the subfamilies Hesperininae and Bibioninae are monophyletic and Pleciinae is paraphyletic. The cladistic structure of the family is Hesperinus + (Penthetria + [Plecia + (Dilophus + Bibionini)]), and relationships between the four genera of tribe Bibionini are unresolved. Eleven genera of Bibionidae are recognized in the generic revision: eight extant genera and three fossil genera. The three fossil genera, Fushunoplecia Hong, Clothonopsis Hong & Wang, and Megeana Meunier, were not available for study, and thus the status of these taxa and their placement within Bibionidae is unresolved. The extant genera are Hesperinus Walker, Penthetria Meigen, Plecia Wiedemann, Bibio Geoffroy, Bibiodes Coquillett, Bibionellus Edwards, Enicoscolus Hardy, and Dilophus Meigen. A diagnosis and descriptions of all available life stages are provided for each of these genera. Additionally, several new generic synonyms are proposed. The fossil genus Bibiopsis Heer is treated as junior synonym of Penthetria. The fossil genus Epiplecia Giard and the extant subgenera Heteroplecia Hardy and Pleciodes Hardy are treated as junior synonyms of Plecia. The fossil genus Lithosomyia Carpenter is a junior synonym of Bibio, and the fossil genus Bibiodites Cockerell is a junior synonym of Bibiodes. Two genera previously included in the family Bibionidae are removed from the family. The fossil genus Mesopleciella Rohdendorf belongs in the extinct family Protopleciidae, and the family placement of the fossil genus Longicornia could not be determined, but is not a bibionid.

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ELECTRONIC FILE - Zoology: Invertebrates