Mt. McKinley Alpine (Erebia mackinleyensis) (Gunder, 1932)
Diagnosis: The wing colour above and below is dull black, but both sexes have a reddish patch on both sides of the forewing, larger in the female. Almost all specimens have a paler medial band on the hindwing underside. Wingspan: 41 to 53 mm.
Range: The range of mackinleyensis extends from eastern Siberia through Alaska and Yukon, just reaching into the Northwest Territories in the Richardson Mountains and into British Columbia at Stone Mountain Provincial Park. An unconfirmed report of this species in the Mackenzie Mountains could possibly be the Magdalena Alpine (E. magdalena).
Early Stages: Larvae are indistinguishable from those of the Magdalena Alpine (E. magdalena). The foodplants are grasses,possibly also sedges and rushes (Juncaceae).
Abundance: Although very local it can be common.
Flight Season: Flies in late June and July, possibly biennial at some locations.
Habitats: The habitat of mackinleyensis is identical to that of the Magdalena Alpine (E. magdalena), in high-elevation boulder fields and scree slopes. Adults most commonly rest on large rocks, but can also be found nectaring on Moss Campion (Silene acaulis).
Remarks: We treat this as a distinct species following Hilchie (1990) with some reluctance. All other arctic butterflies with disjunct populations in the Rocky Mountains are considered to be a single species (e.g., Boloria improba, Boloria astarte, Boloria napaea, Erebia pawslowskii, Oeneis bore, and Colias nastes). These species, however, show clinal variation down the Rockies. Since populations of the Magdalena Alpine (E. magdalena) show no tendency in variation towards mackinleyensis, even in northern British Columbia where the ranges of the two species approach each other, we accept Hilchie's conclusions.
© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.
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