Comparative studies on Culex pipiens group of Japan : 2. Morphological variations in the adults of Culex pipiens group collected from various parts of Japan

Abstract

Comparative morphological studies were made in the colonies of Culex pipiens complex collected from localities covering from northern to southern Japan which represented the forms known by the subspecies names of pallens, fatigans and molestus. The colonies examined were the anautogenous forms from Sapporo (Hokkaido, the northmost island), Sendai (northern Honshu), Tokyo (east Honshu), Nagoya (middle Honshu), Kyoto (west Honshu), Sakito (west Kyushu), Kagoshima (south Kyushu) and Koniya (Amami, southmost island), and the autogenous form from Kawasaki near Tokyo. The biometrical values of 100×D/V of male genitalia defined by us as well as of stem-cell index of wing vein were found to become the smaller as the locality of collection moved from northeast towards southwest, and the ratio of occurrence as well as the size of the dark patches on abdominal sternites became the larger from northeast towards southwest. The shape of white basal bands on abdominal tergites also differed in each colonies, and their margins were almost linear in specimens from northern region while those in southern colonies were arched and expanded medially. The ranges of variation of the above biometrical values were always overlapping between the two neighbouring localities, and no clearcut differenciation could be made between pallens and fatigans forms being recognized as different species or subspecies by some previous authors. The autogenous colony from Kawasaki was the only exception from the above rules in that 100×D/V values were larger than those of the northmost colony from Sapporo. Its character of dark patches on abdominal sternites varied from "absent" to "small" as corresponding with some colonies from southwest Honshu, but the shape of the margin of white bands on abdominal tergites was roughly linear like the colonies from north Japan.