Expansion of the Distribution Range and Pollinators of Canavalia rosea (Fabaceae) in the Ryukyu Archipelago, Japan

Abstract

New localities of Canavalia rosea were found on Okinawa and in the Amami Islands of the Ryukyu Archipelago. The locality on Amami-Oshima marks the northern-most limit of the species in Asia and extends its range approximately 490 km northeastward. At its newly discovered locations, C. rosea is pollinated by female leaf cutter bees and bears fruit. We suspect that the presence of three closely related species of Canavalia with flowers morphologically similar to those of C. rosea is probably one of the main reasons for the visitation by leaf cutter bees to C. rosea in the Ryukyu Archipelago. The female bees exhibited two patterns of behavior during flower visitations and effectively pollinated the flowers of C. rosea only when collecting both pollen and nectar. Pollinators of C. rosea have been reported as being anthopholid bees elsewhere, but are leaf cutter bees in the Ryukyu Archipelago.