A new <i>Automeris</i> from Arizona, including its life history and notes on the <i>Automeris colenon</i> complex (Lepidoptera: Saturniidae: Hemileucinae).
Automeris patagoniensisnew sp. is described from the Patagonia Mountains, Santa Cruz County, Arizona (elev. 1350-1550m), USA. The new species belongs to the Automeris io (Fabricius) group, and is most closely allied with Automeris colenon Dyar (= thyreon Dyar, new syn.), a widely distributed grass-feeding Mexican species. Male and female genitalia are figured, species variation, distribution and natural history are compared and the respective larval and imaginal characters of A. patagoniensis, A. colenon, and A. io draudtiana are discussed and illustrated.