Speyeria hesperis and Speyeria atlantis are distinct species

Abstract

S. hesperis and S. atlantis are distinct species; past reports of "intergradation" between them actually represent polymorphism of silvering within S. hesperis. S. atlantis is always silvered, and has a darker (chocolate-brown to blackish-brown) unh disc; it occurs in eastern North America as S. a. atlantis, then ranges as S. a. hollandi over the boreal forest/aspen parklands from Man. To Alta., where it is widely sympatric with S. hesperis helena; S. a. hollandi also occurs in the Rocky Mts. in Alta.-B.C.-NE Wash.-N Ida., where it is sympatric with S. hesperis beani and S. hesperis brico (B.C., new subspecies). In the Black Hills, S. atlantis pahasapa (new subspecies) is sympatric with S. hesperis lurana. In S Wyo.-Colo.-N New Mex., S. atlantis sorocko (new subspecies) is sympatric with mostly-un silvered S. h. hesperis and mostly-silvered S. h. electa (=cornelia=nikias). S. hesperis has a redder unh disc, and ranges from Manitoba and the Black Hills westward to Alaska and the Pacific and south to New Mex.-Calif.; a majority (11 of 19) of its subspecies are usually-silvered, but only the subspecies in the extreme N and NE and S parts of its range are always silvered, and all subspecies across the middle of its range are predominantly unsilvered; silvered/unsilvered intergradation occurs within S. hesperis throughout the middle of the range, including the northern Sangre de Cristo Mts. of Colo. where unsilvered S. hesperis hesperis intergrades completely with silvered S. h. electa. Except in the extreme northern and southern ends of its range, older larvae of S. hesperis are blacker than larvae of S. atlantis.