Evolutionary geographic relationships among orthocladine chironomid midges from maritime Antarctic and sub-Antarctic islands

Two species of chironomid midges are currently described in the genus Belgica Jacobs, 1900. Belgica antarctica , 1900 is endemic to parts of the maritime Antarctic, and Belgica albipes (Séguy, 1965) is endemic to Îles , a sub-Antarctic archipelago in the southern Indian Ocean. The relationships between these species, and closest known relative (Eretmoptera murphyi Schaeffer, 1914, endemic to sub-Antarctic South Georgia), were by sequencing DNA fragments for domains 1 and 3–5 of 28S ribosomal DNA and the mitochondrial gene c oxidase 1 (cox1). The resulting molecular relationships between the three species were unclear, their position within the subfamily Orthocladiinae of the Chironomidae, as generated by classical , was confirmed. Our data reinforce earlier doubts, based on classical morphological approaches, that the placement of E. murphyi may be incorrect. Further analyses may indeed confirm that the species a third member of the genus Belgica. Genetic distance analysis, limited to the barcode region of cox1, high differentiation between the two populations of B. albipes sampled (one obtained from the type ), suggesting the likely presence of cryptic species within this taxon, and that the taxonomic status of this should be revised. Analysis of cox1 sequences in B. antarctica highlighted a strong genetic structure populations obtained from 12 locations along the Antarctic Peninsula and the South Shetland Islands , with a number of distinctive mtDNA lineages inhabiting geographically distinct areas. In particular, found four different haplogroups constituting geographically close but genetically distinct populations, a pattern likely to have been encouraged by the brachyptery of the members of this genus. We suggest that the different patterns shown by each haplogroup have probably been determined by historical dispersal and colonization during the Pleistocene, and are consistent with their survival in refuges in situ during successive glacial over this period.