Floral Visitors of Critically Endangered Arisaema cucullatum (Araceae) Endemic to Kinki Region of Japan

摘要

Arisaema (Araceae) is one of the most species-rich plant groups in Japan, while 20 out of 64 Arisaema taxa are categorized as endangered species (CR or EN) in the Red List of Japan. Although we need to comprehend their reproductive biology to conserve these species, the knowledge regarding their pollination systems is still limited. In this study, we examined the potential pollinators of A. cucullatum, a critically endangered species endemic to Kinki Region of Japan. To this end, we collected the insects trapped inside the spathes of A. cucullatum as well as the two sympatric Arisaema species in the two native populations, and identified by both morphology and DNA barcoding based on mitochondrial cytochrome oxidase subunit I (COI). Sciaridae were the most abundant family in the trapped insects of A. cucullatum, and one sciarid species accounted for 78.9% of the collected insects. Meanwhile, the insect assemblages trapped inside the spathes of A. kishidae and A. yamatense that grow sympatrically with A. cucullatum were distinct from those of A. cucullatum. Accordingly, the difference in the pollinator assemblages may be important for reproductive isolation among them, although further observation in different populations is needed.