Pseudevernia consocians
Pseudevernia consocians is a species of lichen in the family Parmeliaceae. It is found in both North America and Central America. Some characteristic features of Pseudevernia consocians are its well-developed, numerous isidia, relatively narrow, and the presence of the lichen product lecanoric acid.
Taxonomy
The lichen was originally described as new to science in 1926 by Finnish lichenologist Edvard August Vainio. The type specimen was collected by Danish botanist Frederik Liebmann between Cerro León and La Hoya, Mexico. Mason Hale and William Louis Culberson transferred the taxon to the genus Pseudevernia in a 1966 publication.Description
Pseudevernia consocians has a thallus form that can range from leafy to somewhat bushy. It usually measures between in diameter, and it has a smooth texture with a grayish hue. The lobes that compose the thallus are linear and dichotomously branched, overlapping each other with truncated tips, and they are typically 0.3–1.5 mm wide. Cylindrical isidia are abundant on the thallus surface, presenting tips that are darker than the rest of the thallus. The medulla is loosely packed and has a white coloration. The lower thallus surface is attached through basal holdfasts, with a color ranging from tan to black, sometimes with occasional white mottling. The pycnidia are positioned in either a or arrangement, and they can present as immersed, emergent, or sessile.Other superficially similar species are Pseudevernia cladonia and Evernastrum catawbiense. The former can be distinguished from Pseudevernia consocians by the lack of isidia, while the latter produces soralia rather than isidia.
The expected results for standard chemical spot tests are as follows: upper K+, and medulla K−, C+, KC+, and P−. The cortex contains atranorin and chloroatranorin as major and minor lichen products, respectively, while the medulla contains lecanoric acid as the major substance.
The photobiont partner of Pseudevernia consocians is the green algal species Trebouxia jamesii.