Porsild's bryum (Haplodontium macrocarpum) COSEWIC assessment and status report: chapter 4

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Distribution

Global range

Mielichhoferia macrocarpa is known from North America, southern Siberia, the southern Ural Mountains in Kazakhstan, and the Sayan Mountains of central Asia. Its distribution may be described as holarctic disjunct (Figure 4).

North American range

Brassard and Hedderson (1983) produced the most recent published distribution map for Mielichhoferia macrocarpa when the species was still thought to be endemic to North America. A notable addition to their distribution map discovered in the preparation of this report includes a specimen from Pictured Rocks National Seashore on the south shore of Lake Superior in Michigan collected by A. Jonathan Shaw (1990, see collections examined) (Figure 5). There are currently 27 known locations in North America.

Canadian range

Ten localities occurring in five areas of Canada were verified for this report. Total area of occupation was estimated by measuring colony sizes and density at each site (see Appendix 1). Localities are defined as areas with predictable occurrence of the species and populations were delimited by spatial separation. The localities for M. macrocarpa include one in British Columbia (northface of Mt. Socrates, total area occupied <1m²), three in Alberta (Cadomin, Whitehorse Creek [six populations, total area occupied 20m²], Mountain Park [one population, total area occupied 10m²], and Kananaskis Country [one population, total area occupied ~7m²],) six in Newfoundland in the area of the Great Northern Peninsula (total area occupied 18m², see Appendix 1), and one in Nunavut Territory on Northern Ellesmere Island (one population, area unknown) (Figure 5). There may still be undiscovered populations in northern Canada.