Chemical defense of a primitive Australian bombardier beetle (Carabidae):Mystropomus regularis

The Australian bombardier beetle, Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principally n-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C). Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued that Mystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).