Chromosomal inversion polymorphism was investigated in samples of Anopheles gambiae sensu lato collected from different localities of Tanzania. An. merus was found monomorphic, while two widespread inversion polymorphisms were recorded in both An. gambiae sensu stricto (2Rb/+ and 2La/+) and An. arabiensis (2Rb/+ and 3Ra/+). Two additional polymorphic inversions (2 Rbr and 2Rq), generally associated, were observed in An. arabiensis from the Rift Valley. Observed karyotype frequencies were in agreement with those expected according to the Hardy-Weinberg equilibrium suggesting conditions of panmixia in both An. gambiae s.s. and An. arabiensis in the studied areas.
