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Taxonomic key

Lucidcentral.org an interactive key to Chrionomidae


Taxa

Dixidae

Figure 6. Dixid larva.

The Dixidae, commonly known as meniscus midges for their characteristic larval behavior, are short-lived, mosquito-like flies, although adults do not feed and are short-lived. Dixid larvae (Figure 6) are important ecologically as filter-gatherers of organic matter and prey items for predatory insects and fish. Adults are nondescript midges that are rarely encountered unless specifically sought.

The Nearctic fauna is comprised of 45 currently recognized species belonging to three genera: Meringodixa, Dixa, and Dixella (Peters & Cook 1966; Peters & Barbosa 1970; Peters 1981, 1987). Meringodixa is a relict clade consisting of only M. chalonensis Nowell, whereas the other two genera are equally diverse. Larvae of Meringodixa and Dixella occur in calm waters, whereas those of Dixa are found in flowing waters. Dixid larvae are encountered frequently during benthic macroinvertebrate surveys. If more knowledge of the immature stages, particularly larvae, of the Dixidae were available, they could be included in assessments of stream quality. Moulton has assumed taxonomic responsibility for the Nearctic Dixidae and recent fieldwork in the USA, revealing numerous undescribed species in cryptic species complexes.

Univerisy of Tennessee (PI Moulton)

Dr. Moulton, Univerisity of Tennessee

Moultonís ongoing molecular fingerprinting studies within the family Dixidae have revealed cryptic species within several Nearctic morphospecies, including Dixa brevis, Dixa modesta, Dixa inextricata, and Dixella indiana. Revisionary studies are underway to characterize these species and determine to which entities formal names actually apply. Solid morphospecies of Meringodixa, Dixa, and Dixella have also been detected from samples taken across western North America.