Hypercompe extrema. This taxon was listed by Franclemont (1983), but the specimens represent an undescribed species, known from southeastern Arizona and the Davis Mountains, Texas. Because it is an undescribed species it was not included in the Ferguson and Opler (2006) and Schmidt and Opler (2008) check lists.
- Franclemont JG (1983) Arctiidae. pp. 114-119. In: Hodges et al. (1983).
- Ferguson DC, Opler PA (2006) Check list of the Arctiidae (Lepidoptera: Insecta) of the continental United States and Canada. Zootaxa 1299: 1-33.
- Schmidt BC, Opler PA (2008) Revised check list of the tiger moths of the continental United States and Canada. Zootaxa 1677: 1-23.