Aon Neumoegen. The systematic placement of the genus Aon has had a very checkered past. First described as a species of Cossidae, then moved to the Lymantriidae and subsequently to the Euteliinae, it was again moved to the Catocalinae by Kitching and Rawlins  to render the Euteliidae monophyletic. Fibiger and Lafontaine (2005) then placed it in Dilobinae (= Raphiinae), decisively excluding it from the Lymantriinae based on lack of synapomorphies, which instead variably associated Aon with Pantheinae, Raphiinae, Acronictinae (all Noctuidae) or Erebidae (excluding Lymantriinae). Characters of Aon more typical of Noctuidae as opposed to Erebidae as cited by Fibiger and Lafontaine (2005) include a nodular tympanal sclerite (linear in most Erebidae), tympanal bullae fused (separated in most Erebidae), scaphium membranous (sclerotized in most Erebidae). Re-examination of Aon noctuiformis shows however that the scaphium has a narrow dorsal sclerotization, and the beak-like palpi, forewing pattern and the fine, dense terminal tufts of the female abdomen are unlike any acronictoid (Dilobinae-Acronictinae-Pantheinae) genera. Also, the female ductus seminalis arises directly opposite (dorsal to) the ostium, such that the apparent ductus bursae is actually the basal section of the corpus bursae; in all examined acronictoid genera, the ductus bursae is well-defined with the ductus seminalis arising at the base of the corpus bursae roughly halfway between the ostium and tip of the corpus bursae. The stout, curving flange at the apex of the aedeagus also does not occur in acronictoid genera. The above mentioned characters of Aon (tufted female abdominal terminus, origin of ductus seminalis, flanged aedeagus, beaked palpi) are shared by several genera currently placed in the Hypocalinae (Psammathodoxa, Goniapteryx); furthermore, the COI barcode data clusters A. noctuiformis within Psammathodoxa and Hypsoropha (and never near the acronictoid groups); both DNA data and morphology suggests a close relationship to Psammathodoxa, so we transfer Aon to the Hypocalinae.