Lilljeborg's Peaclam (Pisidium lilljeborgi) is a small (shell length up to 4.5 mm) freshwater peaclam that is distributed from Canada south to locally high elevations of northern California, Utah and New Mexico and in Michigan and New England. In New Mexico it is only known from Nambe Lake in Santa Fe County. During reproduction four eggs develop in brood pouches in the gills, the young are born after 2.5-3.5 months in late July and August.