Cresponea
Cresponea is a genus of lichens in the family Opegraphaceae. The genus, circumscribed in 1993, contains species that were formerly classified in Lecanactis. Cresponea is widely distributed, but most species are found in tropical and subtropical regions. The genus is named in honor of the Spanish lichenologist Ana Crespo.
Description
Cresponea spreads as a thin, paint-like crust that merges with the surface of bark or, less often, rock. The thallus can be smooth or cracked into an irregular mosaic, and on rare occasions it breaks into tiny, discrete. Colours range from chalk-white through pale grey to a muted green; some specimens show a narrow, dark brown margin where the fungal threads alone grow out beyond the. Because there is no separate, the fungal tissue lies directly over the, usually the filamentous green alga genus Trentepohlia, which gives a faint orange tint when the surface is scratched. The lichen never produces isidia or soralia, so it relies on its sexual and asexual fruit bodies for dispersal.The sexual structures are small, button-like apothecia that sit on the thallus with a pinched base. They lack a rim of thallus tissue, instead showing a glossy, often crenulated rim that is conspicuously dark brown to black and remains free of the powdery bloom that coats many related genera. The starts flat, may become gently domed, and is dusted with a fine white or bluish, especially in young apothecia. Inside, the clear hymenium stains blue or reddish in iodine and houses slender filaments whose club-shaped tips carry a dark brown cap; together these caps form a granular that turns yellow in potassium hydroxide solution. Each ascus releases eight long, spindle-shaped ascospores divided by three to nineteen cross-walls ; the walls are thick, and the spores stay colourless. Asexual reproduction occurs in tiny pycnidia embedded in the crust; these produce short, rod-shaped conidia. Most species show no detectable lichen products in chemical tests.
Ecology
Generally epiphytic, Cresponea lichen prefer mature, humid woodlands and are sometimes used as an indicator of old-growth conditions, though a few species tolerate rock surfaces in sheltered sites.Species
, Species Fungorum accepts 23 species of Cresponea.- Cresponea ancistrosporelloides
- Cresponea apiculata
- Cresponea chloroconia
- Cresponea endosulphurea – Brazil
- Cresponea flava
- Cresponea flavescens
- Cresponea flavosorediata – Brazil
- Cresponea follmannii
- Cresponea graemeannae
- Cresponea japonica
- Cresponea leprieurii
- Cresponea leprieuroides
- Cresponea lichenicola – Brazil
- Cresponea macrocarpoides
- Cresponea melanocheiloides
- Cresponea pallidosorediata – Brazil
- Cresponea plurilocularis
- Cresponea premnea
- Cresponea proximata
- Cresponea quinqueseptata – Brazil
- Cresponea sorediata
- Cresponea subpremnea