Figs 101–105, 183, 184, 238, 239. Map 21
Anarta impingens Walker, 1857: 700.
Lasiestra impingens; McDunnough 1938: 72.
Lasionycta impingens; Lafontaine et al. 1986: 264.
Mamestra curta Morrison, 1875a: 96.
Anarta curta; Dyar 1903: 160.
Lasiestra impingens curta; McDunnough 1938: 72.
Orthosia perpura Morrison, 1875b: 66.
Anarta perpura; Dyar 1903:160.
Lasiestra perpura; McDunnough 1938: 72.
Anarta nivaria Grote, 1876: 107.
Lasiestra nivaria; McDunnough 1938: 72.
Type material. Anarta impingens: syntype ♁. [ BMNH, examined]. Type locality: [ Canada, Alberta] Rocky Mountains. Mamestra curta: syntypes 1 ♁, 1 ♀. [ MSU, examined]. Type locality: Colorado. Wilterding (1997) states that there is a holotype, but both specimens are labeled “Type.” Orthosia perpura: holotype ♀. [ MSU, examined]. Type locality: Colorado, not New York as stated in Poole (1989). Anarta nivaria: holotype ♁. [ BMNH, examined]. Type locality: Colorado Territory.
Diagnosis. Lasionycta impingens is a small to medium-sized species (expanse 25– 32 mm) with a gray forewing with orange scales in the medial area and a light yellowbrown hindwing. Th e dorsal hindwing has equally dark discal spot and wide marginal band whereas the marginal band is suffused with the ground color and is more faint than the discal spot on the ventral side. Lasionycta impingens occurs from Yukon to Colorado. It can usually be identified without dissection. Male and female genitalia characters are given in the L. impingens sub-group section.
Distribution and biology. Lasionycta impingens occurs from southern Yukon to Colorado. It is diurnal and nocturnal and comes to light. Adults are common in alpine tundra and are often collected by butterfly enthusiasts. It feeds on nectar of a Penstemon species ( Scrophulariaceae) on the Beartooth Plateau, Montana, as well as on Mertensia paniculata (Ait.) G. Don ( Boraginaceae), and a Senecio, likely S. lugens Richardson ( Asteraceae) at Pink Mountain, British Columbia (BC. Schmidt, pers. comm.). Th e moth is found in July and August.
Geographical variation. Populations of L. impingens are arranged in two subspecies. Th ere is only slight overlap in the appearance of the subspecies and we considered treating them as species despite absence of structural differences. However, occasional specimens from the range of each taxon are very similar indicating that use of subspecies is appropriate (compare Fig. 102 with Fig. 105 and Fig. 104 with Figs 101 and 103).
The CO1 sequences of subspecies L. i. impingens and L. i. curta (Morrison) differ by 0.16 %.