Vespicochory, seed dispersal by vespid wasps, is known to be rare in angiosperms. In the summer of 2023, we documented seed dispersal by Vespula shidai in Aristolochia shimadae, representing the first report from Japan. To explore the potential for vespicochory in closely related species, we conducted field observations in the summer of 2024, focusing on insect visits to freshly dehisced capsules of Aristolochia kaempferi on Awaji Island and the Shikoku Karst in western Japan. Results revealed that seed dispersal of A. kaempferi was facilitated by vespid wasps (Polistes japonicus and V. shidai) and a large ant (Formica). Notably, vespicochory in A. kaempferi was observed for the first time in Polistes and Vespula wasps. Although vespicochory depends on the proximity of vespid wasp nests, V. shidai appears to be the primary seed disperser of A. kaempferi. Furthermore, myrmecochory by a Formica ant was observed for the first time in A. kaempferi.
