Genetic observations on the taxon Anopheles (Cellia) pharoensis Theobald (Diptera: Culicidae).

A photomap of the ovarian polytene chromosomes from Anopheles pharoensis is presented. The arrangement shown is that found in populations from Zululand, South Africa, and represents the arbitrary standard for the taxon. Two X-chromosome arrangements exist in samples from allopatric natural populations. Crosses between females homozygous for the inverted arrangement, Xa, and males carrying the standard arrangement, X+a, give F1 males that are sterile. Females from this cross, and both males and females from the reciprocal cross, are fertile. The simplest hypothesis is that the two X-chromosome arrangements mark two species within the taxon An. pharoensis Theobald. The practical implications are briefly discussed.