Pseudopeltula dicyanophora
Pseudopeltula dicyanophora is a species of cyanolichen in the family Lichinaceae. It forms small, olive-green, shield-shaped scales on calcareous rock. The species is unusual in having two different cyanobacterial partners: a primary single-celled cyanobacterium throughout the thallus, and a secondary filamentous cyanobacterium housed in internal structures called cephalodia. It is known from the Caribbean and the Seychelles.
Taxonomy
Pseudopeltula dicyanophora was described as a new species in 1995 by the lichenologist Aino Henssen, in the same paper that established the genus Pseudopeltula in the family Gloeoheppiaceae. In Henssen's concept, Pseudopeltula includes small, olive-colored, squamulose to cyanolichens with immersed apothecia whose mature structure is more complex than in related genera. The species epithet dicyanophora refers to the thallus having two different cyanobacterial partners: a primary, single-celled cyanobiont and a second, filamentous cyanobiont housed in internal cephalodia.In her remarks, Henssen distinguished P. dicyanophora from the similar P. myriocarpa by its non-stromatic fruiting bodies, the lack of amyloid reactions, its cushionlike thalli with large cavities and an irregular internal hyphal arrangement, and the presence of internal cephalodia. She also noted that its clustered, immersed apothecia are confined to depressions in the thallus and that sterile strands subdivide the hymenium, features she interpreted as steps toward a more stromatic fruiting structure within the group.
Description
The thallus is olive-green and squamulose-peltate, with individual squamules about 1–6 mm across, attached to the substrate by an. The upper surface is smooth and slightly shiny, while the lower surface is. The squamules are usually with incised margins. In cross-section, the thallus is much thicker in the center than at the margin and contains conspicuous internal cavities and cephalodia.Microscopically, the fungal hyphae form an irregular network around colonies of the primary cyanobiont, with longer hyphal segments spanning the cavity spaces. The cephalodia develop within the cavities and contain a filamentous cyanobiont, with trichomes about 7–12 μm thick; as they mature, the filaments become enveloped by fungal hyphae and may become strongly distorted. The apothecia are immersed and aggregated in depressions, with reddish-brown up to about 0.3 mm wide. The hymenium and are non-amyloid and are divided by sterile strands, and the asci are cylindrical with 8 spores. Immature ascospores were reported as ellipsoid and about 9.5–12 × 6–7 μm, and immersed pycnidia produce small rod-shaped conidia.