Porsild's bryum (Haplodontium macrocarpum) COSEWIC assessment and status report: chapter 1

Assessment Summary – November 2003

Common name : Porsild’s bryum

Scientific name : Mielichhoferia macrocarpa

Status : Threatened

Reason for designation : A rare moss with a severely fragmented distribution of 10 confirmed locations in Canada restricted to five general areas. The species grows in mainly mountainous areas on wet calcareous cliffs, in the presence of constant seepage and winter desiccation. Direct threats to populations include natural and human-caused events that destabilize the rock cliff habitat. There has been a recent decline in habitat quality at the two most abundant locations and substantial loss of mature individual plants at one of these. Only one locality is protected. There is uncertainty about the status of northern Canadian populations.

Occurrence : Alberta, British Columbia, Newfoundland-Labrador, Nunavut

Status history : Designated Threatened in November 2003. Assessment based on a new status report.