Lasionycta uniformis (Smith)

Crabo, Lars & Lafontaine, Donald, 2009, A Revision of Lasionycta Aurivillius (Lepidoptera: Noctuidae) for North America and notes on Eurasian species, with descriptions of 17 new species, 6 new subspecies, a new genus, and two new species of Tricholita Grote, ZooKeys 30 (30), pp. 1-156 : 68-69

Lasionycta uniformis (Smith)

Figs 70–81, 227–229, 171–173. Map 16

Scotogramma uniformis Smith, 1893b: 101 . Again described as new in Smith 1894: 58. Lasiestra uniformis ; McDunnough 1938: 72.

Lasionycta uniformis ; Lafontaine et al. 1986: 265.

Type material. Listed under subspecies accounts.

Diagnosis. Ironically L. uniformis is arguably the most variable species in the genus. It is widespread, occurring mostly near timberline in the mountains of western North America. Most populations can be identified by a combination of dorsal forewing and ventral hindwing characters. Th e dorsal forewing ground color is medium to dark gray, usually with discernible lines and less prominent spots, with variable amounts of other colors. The ventral hindwing ground color is pale whitish gray and almost all specimens have a dark thick arrowhead- or chevron-shaped discal spot. The postmedial line is usually more prominent than the marginal band; however, the opposite is true in the nominate subspecies from the Canadian Rocky Mountains. A few populations from the central Rocky Mountains are brown gray, but this is atypical for the species as a whole. In general, the darkness of the ventral hindwing markings correlates with the darkness of the dorsal forewing. Distinguishing features of each subspecies are given in greater detail below.

The male valve has a straight costal margin. Th e corona is comprised of a single row of setae except for a partial double row at the apex. Th e vesica has 0–3 basal cornuti. Th e female genitalia and male antenna are typical for the species sub-group.

The CO1 sequence of L. uniformis is variable with twelve haplotypes separated by up to 1.5 %. They are intermixed with those of L. phoca , L. brunnea , and L. discolor ( Fig. 248 ).

Distribution and biology. Lasionycta uniformis is widely distributed in the mountains of western North America. It occurs from southern Yukon to northern California and Colorado, with an isolated population in eastern Quebec. It flies over alpine tundra and is most common on rocky slopes near treeline. It is predominantly nocturnal and is attracted to light, although it can be found feeding at moss campion, Silene acaulis . Adults have been collected from early July to late August.

Remarks. The variability of this species is a challenging problem in the genus Lasionycta . Variation exists within populations such as that in the Coast Range of southwestern British Columbia and between populations across greater distances. Examples of the latter include different ventral hindwing patterns in the nominate subspecies in the Canadian Rockies and most other populations, the presence of dark populations in south-central British Columbia east of lighter brightly-colored ones in the Coast Range, consistent habitus differences between populations in different central Rocky Mountain ranges, and distinctive disjunct populations on Mt. Shasta in California and Mt. Albert in Quebec. Th e CO1 variation in this species is similar to that found in the habitus. At first glance, variation in the habitus and DNA in Pacific Northwest populations suggests multiple species. However, intermediates between extreme forms are readily found when large series are available and no significant differences between DNA haplotypes exist demonstrating that there is only one taxon, here assigned to L. u. multicolor. In regard to the interpopulation variability, slight overlap in habitus between populations, absence of structural differences, overall similarity of the DNA in light of evidence that DNA variation is common in several populations, absence of sympatry of distinct morphs, suggestion of a cline between subspecies uniformis and multicolor (discussed under subspecies uniformis ), and similar habitat preference across the entire range argue that all populations are best considered a single species, L. uniformis .

Geographical variation. The populations of L. uniformis are arranged in five subspecies.

Figures

Figure 248. Neighbor-joining CO1 tree of the North American Lasionycta leucocycla species-group. Symbols and codes are the same as in Fig. 247. No data is available for Lasionycta carolynae, L. illima, L. leucocycla hampa, L. macleani, L. mono, or L. uniformis handfieldi. The illustrated specimens demonstrate the variation in appearance of the species-group and are scaled to the same size.