Abstract
An oriental swallowtail butterfly, Papilio memnon, is highly polymorphic and divided into many subspecies, races and forms. It ranges over the Kyushu Main Island (subsp. thunbergii), the Amami Is. and the Okinawa Is. (subsp. pryeri) in Japan, and is also widely distributed in Formosa (subsp. heronus). In these habitats it is known as one of the commonest species. On the contrary, only three male specimens have been recorded from the Sakishima Is., located between the Okinawa Is. and Formosa, where no females have been hitherto found. One of these three males is similar to subsp. heronus. In 1964, one male and two females were captured from Iriomote Is., the Sakishima Is,. The male specimen is not similar to subsp. heronus but nearly the same as subsp. pryeri. The females are extraordinarily albinized in comparison with any known races from Japan, Formosa or their neighborhoods. Accordingly, the precise taxonomic name for P. memnon from the Sakishima Is. should remain innominate at present. A major reason why P. memnon is rare in the Sakishima Is. may lie in the scantiness of the cultivated Citrus, its main food-plant.
