Distribution and ecology of Vertigo nylanderi Sterki, 1909 in the western Great Lakes region

The land snail Vertigo nylanderi, previously reported from only six modern global sites, was located at 22 stations in north-central Minnesota, northern Michigan, and eastern Wisconsin. Its populations are limited to nutrient-rich, forested wetlands (typically dominated by Tamarack or Black Ash) that are underlain by calcareous substrates. Most sites are within 40 km of the Lake Michigan and Lake Huron shorelines. This species was found to be morphologically distinct from other conchologically similar taxa such as V. arthuri (von Martens, 1884), V. hubrichti (Pilsbry, 1934), and V. paradoxa Sterki, 1900. Although 54 other terrestrial gastropod taxa have been observed to coexist with V. nylanderi, only 12 of these occur in at least 50% of sites. The cool, wet, calcareous habitats that support V. nylanderi appear to be similar to late Pleistocene environments, and it is possible that this species represents a relict from that period.