Sagedia
From Wikipedia, the free encyclopedia
| Sagedia | |
|---|---|
 | |
| Sagedia simoensis | |
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Pertusariales |
| Family: | Megasporaceae |
| Genus: | Sagedia Ach. (1809) |
| Type species | |
| Sagedia zonata Ach. (1809) | |
Sagedia is a genus of lichen-forming fungi in the family Megasporaceae. Sagedia species are crustose lichens with immersed, wart-like fruiting bodies that show a depressed disc and a distinct, often raised margin. The genus was established in 1809 by the Swedish lichenologist Erik Acharius and contains 15 recognised species. These lichens grow on rocks or bark and are characterized by a tightly adherent crust that ranges from grey to pale brown, often with faint concentric bands. The genus belongs to a group of related lichens sometimes called the aspicilioid crusts, and its exact boundaries remain debated.
The genus Sagedia was introduced by the Swedish lichenologist Erik Acharius in 1809, with a brief Latin diagnosis that emphasised a tightly adherent crust (a crustose thallus) and wart-like apothecia that arise from, and are partly sunk into, the thallus. He described the apothecial top as a coloured membrane bearing a disc-shaped depression, covering an internal, thallus-like "nucleus"; he summarised the thallus itself as "crustaceous, uniform".[1]
Acharius's protologue included two species. Sagedia laevata (now Aspicilia laevata) was characterised by a contiguous, smooth crust of dirty grey-green colour and by blackish-brown warty apothecia whose discs are impressed and concave with a slightly raised, somewhat reddish rim; he recorded it "on rocks near Carlberg" in Södermanland (Sweden).[1] The type species, Sagedia zonata, was said to have a very thin, finely cracked ash-grey to glaucous crust marked by several irregular whitish lines that give a zoned appearance at the margin; its apothecia are black, with the disc impressed into the thallus and a gently elevated, nearly entire rim. Acharius noted it "on stones at Särna, near the mountains" in Dalarna.[1]
In modern treatments, Sagedia is placed within the Megasporaceae among the "aspicilioid" crusts—lichens with a trebouxioid green alga and lecanorine apothecia (with discs rimmed by thallus tissue) that are usually immersed in the thallus. Molecular work on Aspicilia (in the loose sense) has split that complex into segregate genera and reintroduced Sagedia (alongside Circinaria), with other lineages assigned to Lobothallia, Megaspora, and later the resurrected or newly described Aspiciliella and Teuvoa. That said, only a fraction of European material has been sequenced, and the boundary between Aspicilia sensu stricto and Sagedia remains disputed: some authors sink Sagedia (with Circinaria, Megaspora and Aspiciliella) to subgeneric rank under a broad Aspicilia, retaining Lobothallia as the only separate genus. Nimis adopts a pragmatic approach—sympathetic to the broad concept but, pending wider sampling, provisionally using the narrower segregates and leaving unresolved species in Aspicilia. [2]