Chromosomal identification of eight species of the subgenus Edwardsellum near and including Simulium (Edwardsellum) damnosum Theobald (Deptera: Simuliidae)

Abstract

Examinations of the banding pattern of polytene chromsomes from larval salivary glands of the population in west Africa once thought to be a single species, Simulium (Edwardsellum) damnosum, revealed eight species all within the Nile subgroup of the complex. The following names were proposed: S. (E.) squamosum Enderlein, S. (E.) yahense n.sp., S. (E.) soubrense n.sp., S. (E.) sanctipauli n.sp., S. (E.) dieguerense n.sp., S. (E.) damnosum Theobald, S. (E.) sirbanum n.sp. and S. (E.) sudanense n.sp. Micromorphological characters by which there species are distinguished include interspecific inversions, different sets of intraspecific inversions, different sets of sex chromosomes and a few micromorphological features other than the banding pattern. By following the logical sequential development of interspecific inversions both a key to the species and a phylogenetic chart have been drawn up. Analysis of the proportions of alternate sequences for random distribution or not with ther Hardy-Weinberg equation have confirmed the existance of distinct populations, uncovered an example of incipient speciation and showed the existance of a genetic variant of S. damnosum which could possible colonize below dams.