This species was described over a century ago and has been treated taxonomically in multiple detailed treatments (e.g., Ekman 1996, Lendemer et al. 2016). It is a highly distinctive crustose lichen that can easily be recognized in the field and laboratory.
Why suggested for a Global Red List Assessment?
Endemic to eastern North America, this species is widely distributed from southern Canada to central Florida in the United States (Brodo et al. 2001, Ekman 1996, Lendemer et al. 2016).
Population and Trends
Comprehensive detailed population data are unavailable for this taxon. The status of the population is suspected to be stable given that it is common and widespread in many habitats and there is no indication the species is restricted to a narrow range of habitats or substrates (Ekman 1996, Lendemer et al. 2016).
ASSESSMENT: Least Concern
Given the large number sites where it is extant, large geographic range, large population size, and absence of documented or suspected declines, the species does not meet the thresholds for any threat criteria.
Population Trend: Stable
Habitat and Ecology
Bacidia schweinitzii primarily occurs on the bases and boles of trees, especially in humid habitats. It is most often found on the bark of hardwood trees, but frequently also occurs on the bark of certain conifers such as cypress (Taxodium). It is widely distributed in temperate and subtropical areas of eastern North America.
Threats to this species are primarily habitat loss, air pollution and urbanization as it does not typically occur in urban areas, highly polluted sites, or areas that have been recently strongly disturbed.
Many sites where this species occurs are located on public lands and in protected areas where it is incidentally protected. It would benefit from broader awareness and training as to the impacts of broad scale disturbance, urbanization and air pollution on lichens.