Common Freckle Pelt Lichen

<em>Peltigera aphthosa</em> is a foliose lichen in the family Peltigeraceae, order Peltigerales, commonly known as common freckle pelt or speckled felt lichen. This species holds the conservation status of Extinct on the IUCN Red List, representing a serious loss of biodiversity. <em>Peltigera aphthosa</em> has been recorded in Denmark, Norway, Sweden, and the United States. Historically, this lichen grew in cool, humid environments including boreal and montane forests, typically on mossy ground, rocks, and tree bases in old-growth habitats. Like other members of the genus Peltigera, <em>Peltigera aphthosa</em> is a tripartite lichen containing a cyanobacterial photobiont (providing nitrogen fixation) in addition to the primary green algal photobiont and fungal mycobiont, making it an ecologically significant contributor to nutrient cycling. Its large, lobed thallus was characterized by distinctive dark cephalodia — wart-like structures housing the nitrogen-fixing cyanobacteria. The extinction of this species underscores the vulnerability of lichens to habitat degradation, air pollution, and climate change. Biological traits of this species remain poorly documented in the scientific literature.