Acyrthosiphon or Aulacorthum species

Two species of Acyrthosiphon and two of Aulacorthum are occasionally found on lettuce in Australia.

Winged adults (alatae) key out elsewhere in this key but wingless adults (apterae) are more difficult to distinguish, except for Aulacorthum circumflexum which bears a distinctive U-shaped dark patch on the abdomen (shown at right). The species are differentiated by Eastop (1966) by a series of measurements of various parts of the body. In addition, A. solani has the face and anterior part of the head spinulose while these areas are smooth in Acyrthosiphon species. This feature can really only be seen well in slide mounted specimens examined under a good quality microscope.