Pan-American Chironomus calligraphus Goeldi, 1905 (Diptera,Chironomidae): Species or Complex? Evidence from External Morphology, Karyologyand DNA Sequencing.

Chironomus (Chironomus) calligraphus Goeldi, 1905, previouslyknown from the Neotropics, is newly identified as a member of midge communitiesacross the southern U.S.A.. The karyotype is described for the first time,as is that of the related Chironomus spec. WOC, known only as larvaefrom the southeastern United States. Morphological descriptions for the adultmale, pupa, and larva of C. calligraphus are emended, including charactersdistinguishing the species in the southern Nearctic. Intraspecific variationdiminishes the diagnostic value of certain standard morphometrics. The firstgene sequences for C. calligraphus are offered based on a fragmentof mitochondrial cytochrome c oxidase subunit II. Patterns of variation arenot congruent among data sets. Morphology and karyology show minor and clinalregional differences, whereas mtDNA sequences suggest the sympatric coexistenceof two haplotype groups. However, taxonomic distinctions are considered unwarrantedpending further evidence. C. calligraphus thrives in a range of conditionsand habitats, including small and temporary waters. This ability is presumedto have facilitated the species' wide Pan-American distribution, butalso its high potential as a nuisance to humans. [ABSTRACT FROM AUTHOR]