木曽谷のギフチョウとヒメギフチョウ

抄録

Luehdorfia japonica and L. puziloi are phylogenetically primitive, oriental Papilionid butterflies. Their Japanese distribution is well investigated: the former ranges over central to western Honshu, while the latter over the central to northeast of Honshu and Hokkaido. Thus there exists a quite distinct "habitat segregation" among the two, and the "Luehdorfia-line" is advocated as a biogeographical boundary-line. The Kiso Valley is just located on the "Luehdorfia-line", where two Luehdorfia species are localized in a few separate habitats and less common than the adjacent regions: L. puziloi is restricted to the northern part and L. japonica is found only from the southern part of the Valley. Neither has been recorded from the middle part. Such characteristic may be explained by the following facts: The Valley is situated between the steep Kiso Mountains and Mt. Kiso-Ontake, of which volcanic activity was in Quaternary. Moreover, the greater part of this district is covered with well-developed evergreen coniferous forest inhibiting the spontaneity of both food-plants and adult feeding-plants. The food-plants of Luehdorfia are also phylogenetically primitive Aristolochiaceae: Heterotropa in L. japonica and Asiasarum in L. puziloi. They had reached us from the Asian Continent during or prior to the Tertiary, extended their areas of distribution and have produced many geographical races. L. japonica chooses Sect, Bicornes in preference to the remainders of genus Heterotropa as the ovipositing plants and food-plants. In this paper, it is postulated that the geographical or ecological distribution of L. japonica has an intimate connection with the spontaneity of its main food-plant, Sect. Bicornes.