Polymorphism in a Group of Mimetic Butterflies of the Ethiopian Nymphaline Genus Pseudacræa

A LITTLE more than two years ago Dr. Karl Jordan informed me that he had been studying the male genital armature of the Pseudacræas, and that he could not find any difference between the "species" of a large group made up of Linné's eurytus and its numerous allies on the west coast, of Neave's hobleyi, terra, and obscura in Uganda, of Trimen's rogersi of the Mombasa district and his imitator of Natal. All these forms possess patterns mimetic of species of the ine genus Planema. The conclusion was a very startling one. If each mimetic Pseudacr a had been confined to a single area and had interbred on its margin with the Pseudacrææ of surrounding areas with different mimetic patterns, we should have been confronted with a more remarkable and complex example than any as yet known (except perhaps Papilio dardanus), but one that raised no special difficulty. Dr. Jordan's discovery, however, involved far more than this: it led to the remarkable conclusion that the sexually dimorphic P. hobleyi, mimicking the sexuaily dimorphic Planema macarista in the Entebbe district, was the same species as the two monomorphic Pseudacr as flying in the same forests with it, viz. P. terra and P. obscura, mimicking respectively the sexually monomorphic Planema tellus and P. paragea.