First report of vespicochory in Aristolochia shimadae Hayata (Aristolochiaceae) in Japan

To assess vespicochory in Aristolochia (Aristolochiaceae), we conducted preliminary observations of Aristolochia shimadae under cultivation and in its natural habitat. Two paper wasp species (Polistes spp.) were observed visiting freshly dehisced capsules of cultivated plants of A. shimadae. After removing the seed from the capsule and licking the juicy and sticky substance surrounding it, paper wasps bit off and carried away only a part of the raphe. This behavior suggests that the capsule, including the substance surrounding the seeds, is attractive to them, and the raphe is equivalent to an elaiosome. In our field observations of A. shimadae in a natural habitat, a wasp (Vespula shidai) carried away a seed after licking the juicy and sticky substance surrounding it. This observation of vespicochory is the first report on A. shimadae and the first on angiosperms in Japan.