A total of 6 species of the Pyretophorus (4 species) and Neomyzomyia (2 species) series of the subgenus Cellia of Anopheles were used for metaphase karyotype analysis. Anopheles subpictus and An. vagus exhibit 4 and 2 forms of mitotic karyotypes, respectively, which are attributable to different types of Y chromosomes. Such distinctive mitotic chromosomes may reflect interspecies differences within each of these 2 taxa. Two distinct species, An. indefinitus and An. sundaicus, show similar metaphase karyotypes, particularly with regard to the size and shape of the sex chromosomes. Likewise, An. tessellatus and An. kochi, which are distinct species of the Neomyzomyia Series, also have metaphase karyotypes that resemble each other. They exhibit a typical feature of telocentric sex chromosomes resembling those of the An. dirus complex and the other species of the Leucosphyrus Group. Like the other cases of the Oriental Anopheles, heterochromatin has played a significant role in chromosome evolution of the 6 species.