[The karyotype of Omisus caledonicus (Edwards) (Diptera, Chironomidae)]

Karyotype of Omisus caledonicus with 2n = 14 is described, all chromosomes are acrocentric, heterochromatin centromere is vacuolized. The following sequence discovered: A1, A2, B1, B2, C1, C2, D1, D2, E1, F1, G1 and G2. Simple inversions are found in chromosomes A-C and G, a complex reconstruction with 3 break points are observed in chromosome D. All reconstructions are large (from 66 to 99% of bands). According to phylogenetic reconstructions for morphological characters (Saether, 1979) and data on karyotypes it may be considered that O. caledonicus is one of much more primitive species in the tribe Chironomini.