<Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Pamphilioidea </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Unicalcarida </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Cephoidea (stem sawflies) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Siricoidea (horntails or wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Xiphydrioidea (wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> parasitism </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Orussoidea (parasitic wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> "wasp waist" 200mya </Td> <Td> <P> APOCRITA (ants, bees, wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> <P> Pamphilioidea </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Unicalcarida </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Cephoidea (stem sawflies) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Siricoidea (horntails or wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Xiphydrioidea (wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> parasitism </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Orussoidea (parasitic wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> "wasp waist" 200mya </Td> <Td> <P> APOCRITA (ants, bees, wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> <P> Pamphilioidea </P> </Td> </Tr> <Tr> <Td> Unicalcarida </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Cephoidea (stem sawflies) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Siricoidea (horntails or wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Xiphydrioidea (wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> parasitism </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Orussoidea (parasitic wood wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> "wasp waist" 200mya </Td> <Td> <P> APOCRITA (ants, bees, wasps) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr>

What is the defining structure of the aculeate hymenoptera