The JapanSociety ofMedical Entomology and Zoology {Med. Abstract: Larval polytene chromosorne banding patterns of Simulium (Simulium) eximium de Meijere, 1913 collected from West Java and Sumatra in Indenesia were observed and a standard map was presented. This species had three chromosome pairs which were numbered I-III in decreasing order of size. Each centrornere of all chromosomes was distinguished by an expanded region with heterochromatin. A haplotype involving two distinctive

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... tic bands in the centromere (2IA) and section 20B of the chromosome I was heterozygous in most of the males from the population of Puncak (West Java) and appeared to be sex-linked. The differences in chromosomal polyrnorphism, coupled with those in sex-related banding, suggest that two sibling species exi$t in the S. (S.) eximium morphospecies, one in Puncak (West Java) and the other in Danau Ranau (South Surnatra).