Larval salivary gland chromosomes of the blackfly, Simulium (Gomphostilbia) yaeyamaense (Diptera : Simuliidae) from Ryukyu Islands, Japan

Larval salivary gland chromosomes of the blackfly, Simulium (Gomphostilbia) yaeyamaense Takaoka, 1991,from the Yaeyama Island group of the Ryukyu archipelago, were observed and mapped. This species had three pairs of polytene chromosomes. The longest pair, chromosome I, is metacentric and the two shorter pairs, chromosomes II and III, in descending order of length, are submetacentric. The centromeric region of all chromosomes was not expanded and barely recognized by the existence of a heavy band. The nucleolar organizer was situated in section 18 of chromosome I. The Balbiani ring, double bubble and the Parabalbiani ring were situated in sections 47,46 and 61 of chromosome II, respectively. From three populations examined, one inversion (IIIL-1) was always heterozygous in females, and four other inversions (IIIL-2,IIIL-3,IIIL-4 and IIIL-5), were polymorphic and found as heterozygote in both sexes. This study is the first to map the larval salivary gland chromosomes of the subgenus Gomphostilbia, and to record the heterozygous inversion related to the female sex among the Oriental Simuliidae.