Ectemnorrhininae (Coleoptera, Curculionidae) represent a specific subfamily of weevils, which are found only on volcanic islands in the Southern Indian ocean. The islands, which are largely isolated from each other, constitute a distinctly individualized biogeographical province. On this archipelago, Ectemnorrhininae form the most important group of insects, originating from a primitive stock, the origin of which although still unknown, is probably antarctic. This group includes some 30 recorded species, which appear to be differentially distributed among the islands, some of these islands having been only recently inhabited owing to the recent period of their emergence. Until now, classification of Ectemnorrhininae was essentially established on the sole basis of adult and larval morphological criteria. More recently, alimentary habits have been taken into account. The present study is part of a more comprehensive approach, aimed at understanding the Curculionidae phylogeny, using cytogenetic analysis, which has not been done before. Karyotypes of 2 closely related species pertaining to the Canonopsini tribe, Christensenia antarctica and Neocanonopsis dreuxi, were established, utilizing a computerized analysis which allows the grouping of objects (here chromosomes) in accordance with similarities (here length and centromeric index) detected between them. Both species are characterized by the same general chromosomal formula, 10 AA + Xy(p), this type of formula being shared by many species of Curculionidae. Centromere location is more variable in chromosomes of N dreuxi than in those of C antarctica. These observations am compared with the findings of a previous study which determined the karyotype of 3 different species of Ectemnorrhinini. Further analytical studies using a wider range of genera and species are required for establishing complete phylogenetic relationships.
