Chromosomal characteristics and evolutionary relationships of the Palearctic black fly Simulium carthusiense (Diptera: Simuliidae)

Abstract

The giant, polytene chromosomes of Simulium carthusiense Grenier & Dorier, 1959 were mapped, and all rearrangements were resolved relative to the standard banding sequence for the S. vernum group. The species is chromosomally cohesive from Austria to Spain, and is characterized by a chromocenter, two unique fixed inversions, 10 unique autosomal polymorphisms, and undifferentiated sex chromosomes. Rare individuals (3%) have two types of supernumerary chromosomes, representing the third example of a simuliid species that carries two different supernumeraries in the same individuals. Band-sequence comparisons with chromosomal outgroups indicate that S. carthusiense is the sister species of a clade that includes S. beltukovae (Rubtsov, 1956), the S. cryophilum complex, and S. urbanum Davies, 1966.