Cytogenetic evidence for three sibling species in Anopheles fluviatilis (Diptera: Culicidae)

Three arrangements of chromosome arm 2 occur as homozygotes, without observable heterozygotes, in populations of Anopheles fluviatilis James. This indicates positive asortative mating between populations having different arm 2 arrangements and is taken as evidence for three sibling species within A. fluviatilis. This finding confirms an earlier hypothesis that the taxon is a mixture of biological forms, which was indicated by heterogeneity between populations in their malaria transmission potential on the Indian subcontinent. Rearrangement of arm 2 involves two paracentric inversions, 2q super(1) and 2r super(1), giving three types of arm 2:2 + q super(1) + r super(1), 2q super(1) + r super(1), and 2 + q super(1)r super(1). Photomaps of the ovarian polytene chromosomes are presented.