Pseudopeltula myriocarpa
Pseudopeltula myriocarpa is a species of rock-dwelling squamulose lichen in the family Lichinaceae. It forms small, olive-colored, shield-shaped scales on limestone and dolomite. The species is the type of its genus and is distinguished by its fruiting bodies, which become aggregated into dark, spot-like stromatic patches up to about 2 mm across. It occurs in Mexico and the Caribbean.
Taxonomy
Pseudopeltula myriocarpa was described as a new species in 1995 by the lichenologist Aino Henssen. In that paper, Henssen designated P. myriocarpa as the type species of Pseudopeltula, a genus of small, olive cyanolichens with an thallus and unusually complex, mature apothecia.The species epithet myriocarpa refers to the many small apothecia that ultimately become packed together in a partly stromatic tissue. In Henssen's key to Gloeoheppiaceae, P. myriocarpa is identified by its fruiting bodies being aggregated into stromata that appear as circular to rosette-shaped spots up to about 2 mm across. Henssen also emphasized that, unlike Pseudopeltula heppioides, P. myriocarpa develops true stromatic fruiting bodies.
A 2024 phylogenetic reclassification of the Lichinomycetes did not support recognizing a separate family for Gloeoheppia, and instead treated the genus within Lichinaceae.
Description
The thallus is olive-colored and made up of squamulose to units, with margins that curve downward and a lower surface that is. Individual squamules may be single or clustered, often convex to somewhat spherical, and can reach about 7 mm in length. They attach to the substrate by rhizoidal strands that may merge into an. In cross-section, the thallus is typically about 380–480 μm thick and includes a well-developed tomentum layer.Fruiting bodies are produced in dark brown to blackish stromata that form spot-like patches up to about 2 mm wide. The spore-bearing layer is about 110–115 μm tall and becomes subdivided by sterile hyphal strands. In iodine it stains deep blue and then turns brown-red, while the stains bluish. The cylindrical asci usually contain 6–8 spores, and the ascospores are mainly, ellipsoid, and colorless, although two-celled spores were occasionally observed. Pycnidia are immersed and can be large, producing small rod-shaped conidia. Henssen described the development of the stromata as a cumulative process: small apothecia form densely, the hymenium becomes partitioned, and additional apothecia arise within or beneath older tissue, producing a single, horizontally spreading stromatic patch with uneven ridges or wart-like projections.