Figs 57, 58, 168, 224. Map 13

Anarta lagganata Barnes & Benjamin, 1924: 118.

Lasiestra lagganata; McDunnough 1938: 72.

Lasionycta lagganata; Lafontaine et al. 1986: 263. Type material. Holotype ♀ [USNM, examined]. Type locality: Laggan [Lake Louise], Alberta.

Diagnosis. Lasionycta lagganata has a slate-gray forewing with nearly obsolete dark lines and a white hindwing with a large discal spot and dark marginal band. The forewing is often quadrate with a blunt apex. Males have a long digitus shaped like an acute triangle and a large triangular cucullus with a corona comprised of four irregular rows of setae. Th e male antenna is weakly biserrate, about 1.6× as wide as the shaft.

Lasionycta lagganata has a limited range in the Canadian Rocky Mountains where it is only likely to be confused with L. quadrilunata yukona. Specimens of L. lagganata have a nearly straight antemedial line whereas that of L. q. yukona is sinuous. Males can be distinguished by the shape of the digitus, long in L. lagganata and short and broad in L. quadrilunata. Th e corpus bursae of L. lagganata is larger than that of L. quadrilunata. Lasionycta lagganata is also similar to L. carolynae that occurs in Yukon. Differences between these species are described under L. carolynae.

Distribution and biology. Lasionycta lagganata is only known from three localities in southwestern Canada: Banff and Waterton National Parks in Alberta and the Purcell Mountains in southeastern British Columbia. It is diurnal and flies on fine shale scree slopes with sparse vegetation. Adults have been collected from mid-July to mid-August. Lasionycta lagganata is very rare in collections.