Population cytogenetics of Austrosimulium bancrofti (Diptera: Simuliidae) in eastern Australia

Abstract

Larvae of Austrosimulium bancrofti (Taylor) from four sites in eastern Australia were cytologically examined. Evidence for eight cytoforms is presented. These are A. bancrofti Ipswich A and B, A. bancrofti Willawarin, A. bancrofti Canberra, and A. bancrofti Eidsvold A, B, C, and D. Austrosimulium bancrofti Ipswich A, A. bancrofti Willawarin, and A. bancrofti Canberra were not collected in sympatry, but they showed fixed chromosomal inversion differences, unique sex-determining systems, and floating inversions. Larvae of A. bancrofti Ipswich A were collected in sympatry with A. bancrofti Ipswich B and A. bancrofti Eidsvold A, B, C, and D. However, low numbers of A. bancrofti Ipswich B and A. bancrofti Eidsvold A, B, C, and D were sampled. In sympatry these cytoforms are either positively assortatively mating or randomly mating. The data suggest that A. bancrofti is a complex of at least eight sibling species. Further sampling at sites intermediate to those reported here is necessary to confirm this hypothesis.Key words: Simuliidae, Austrosimulium, sibling species.