A new species Megabruchidius sophorae (Coleoptera, Bruchidae), feeding on seeds of Styphnolobium (Fabaceae) new to Bruchidae

Abstract

A new species Megabruchidiussophorae (Insecta, Coleoptera) is described from Japan (Honshu). The larval host of this bruchid is the seeds of the tree legume 'enju', or chinese scholar tree, Styphnolobium japonicum (a senior synonym of Sophora japonica), which is a new host genus to Bruchidae. Styphnolobium is positioned basally in molecular phylogeny of the leguminous subfamily Papilionoideae. Other members of Megabruchidius are known to feed on Gleditsia, the tree legumes that belong to the most ancestral subfamily Caesalpinioideae. Therefore, Megabruchidius utilizes ancestral groups of legumes as its host plants. Megabruchidius has been inferred to be ancestral, based on its behavior. The character state of the host for this third Megabruchidius species supports that the genus is ancestral, at least in the subfamily Bruchinae. We also reviewed the genera closely related to Megabruchidius, i.e., Bruchidius and Sulcobruchus in Bruchidini, and wrote a key to the species in the genus Megabruchidius.