Anopheles flavirostris (Ludlow) from Lombok Island, Indonesia, was crossed withAn. minimus species A (CM strain) from Thailand and species E (ISG strain), a new sibling species, from Japan, to determine genetic compatibility. We also compare the scanning micrographs of female cibarial armature of these three species. BothAn. minimus CM and ISG females crossed withAn. flavirostris males produced eggs without embryos. OneAn. flavirostris female crossed with anAn. minimus CM male deposited unhatchable eggs with an 18% embryonation rate. The scanning micrographs of the cibarial armature clearly show significant differences amongAn. flavirostris and the two sibling species of theAn. minimus complex. These results support the specific status ofAn. flavirostris. Previous records ofAn. minimus Theobald in this country are also discussed.