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. 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.

See notes on alate Aulacorthum solani here.
See notes on Aulacorthum circumflexum here.
See notes on alate Acyrthosiphon spp here.