Psilolechia

The genus Psilolechia was established by Abramo Bartolommeo Massalongo in 1860.[1] Formerly classified in the family Pilocarpaceae,[2] molecular phylogenetic analysis showed that Psilolechia represented a distinct lineage that deserved placement at the familial level, the Psilolechiaceae, which was formally circumscribed in 2014.[3] This arrangement was accepted in later large-scale updates of fungal classification.[4][5][6] Psilolechiaceae is in the order Lecanorales, in the suborder Sphaerophorineae, which also includes the families Pilocarpaceae, Psoraceae, and Ramalinaceae.[3]

Psilolechiaceae is a monogeneric family of crustose lichens with effuse, ecorticate (lacking a cortex), leprose thalli formed by goniocysts (aggregations of photobiont cells surrounded by short-celled hyphae) containing Trebouxia or stichococcoid algae. The apothecia lack a distinct margin, and the asci are 8-spored and have a cylindrical to clavate shape. They feature a central, elongated tube-like structure, and a non-amyloid ascus wall surrounded by a thin outer layer. Both the tube-like structure and the thin outer layer stain dark blue in K/I. Ascospores are oblong-ovoid to tear-shaped, simple (rarely 1-septate in P. leprosa), and hyaline.[3]

Psilolechia contains four species:[7]

• Psilolechia clavulifera (Nyl.) Coppins (1983)[8] – widespread
• Psilolechia leprosa Coppins & Purvis (1987)[9] – north-west Europe; Greenland
• Psilolechia lucida (Ach.) M.Choisy (1949) – widespread
• Psilolechia purpurascens Coppins & Purvis (1987)[9] – Tasmania

Psilolechia species grow in locations that are humid and shaded.[3] P. leprosa tends to grow on mineral-enriched rocks and siliceous rocks,[10] and is often recorded around old mines.[11]