Note: The current volume of the "Flora of the Pacific Northwest" has these all lumped together as Amelanchier alnifolia, with no varieties. I've just kept them separate for the time being.
Western Serviceberry: Amelanchier alnifolia var. alnifolia - Currently found in the vicinity of Glenwood, WA. Also expected to be found in Hellroaring Canyon and along the Island Springs Trail.
Western Serviceberry: Amelanchier alnifolia var. semiintegrifolia -
Cusick's Serviceberry: Amelanchier cusickii (Synonyms: Amelanchier alnifolia var. cusickii, Amelanchier basalticola, Amelanchier florida var. cusickii, Amelanchier florida) - Currently found in the Klickitat River Canyon and forests north and east of the canyon as far as the Yakama Reservation.