Abstract
The subcostal pale spot (Sc p) and fringe pale spot (F p) which are the distinguishing features between Anopheles sinensis and A. lesteri have been found to have a wide variability. The F p (+) of A. sinensis was lacking in 0.3% to 20.5% of individuals examined while the Sc p (+) was a comparatively more stable character, lacking in 0.8% to 6.4%. In A. lesteri, the F p (+) occurred in 1.6% and Sc p (+) 24.9% of the mosquitoes studied. The F p (-) is considered to be stable in A. lesteri. A new kind of wing spot (H p : humeral pale spot) that had never been reported in A. sinensis was found in the Tomakomai and Engaru strains; the rates of appearance of the spots were 23.3% and 23.7% respectively. The frequency of clasper movements in the males of the Tomakomai and Engaru strains during induced copulation was 14.3 and 14.6 respectively, whereas it was about 8 in the males of the other three strains of A. sinensis; this difference was significant at the 1% level. Moreover, these two strains showed a significant difference in the frequency against all the other 5 species or strains tested. From these results it is suggested that there have occurred genetic divergence in the Tomakomai and Engaru strains from the ancestral A. sinensis.
