Abstract
Comparative morphological studies were made with the adults of three laboratory bred colonies of Culex pipiens s.l. which were originally collecte d from Tokyo (DE) in eastern Japan and from Amami (KO) and south Ryukyu (TA) in the south. The latter two represent the so-called fatigans-form, while the first is of pallens-form. Conspicuous patches composed of dark scales were detected on abdominal sternites III to VII of the latter two colonies, which were found to lack almost completely in the first. The patches, when present, were more conspicuous in the males than in the females. Differences were also seen in the transverse white bands on abdominal tergites of females, which were nearly linear in the former and were arched posteriorly in the latter two. Differences between the above two forms were also seen in the cell-stem index of the wings, which were seen more obviously in the males with the critical value of about 2.40 between the groups. The measurements of the male genitalia were made with the values of 100×D/V in the place of DV/D of the previous authors. The two groups could be differentiated at D/V value of 50 where those for DE were larger and for TA and KO were smaller than this value. All of the biometrical values of the hybrid colonies of the two groups discussed here were roughly intermediate. Although the above two groups were found to differ in the experimental populations, overlappings of the individual values between the groups were always seen for these values.
