Simuliidae are morphologically very conservative in comparison with many other groups of Diptera (Crosskey,
1990) with consequent problems in defining all taxonomic ranks including subgenera, species groups and species.
At the species level sibling species are the norm (Adler et al. 2010), and polytene chromosome analysis currently
provides the most reliable method for assessing species status and defining species boundaries, because diagnostic
chromosomal inversions provide a direct test of reproductive isolation.