Myochroidea
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| Myochroidea | |
|---|---|
 | |
| Myochroidea rufofusca | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Genus: | Myochroidea Printzen, T.Sprib. & Tønsberg (2008) |
| Type species | |
| Myochroidea rufofusca (Anzi) Printzen, T.Sprib. & Tønsberg (2008) | |
| Species | |
Myochroidea is a genus of lichen-forming fungi of uncertain familial placement in the order Lecanorales.[1] It has four species of grey or brown-grey crustose lichens.[2]
The genus was proposed in 2008 by the lichenologists Christian Printzen, Toby Spribille, and Tor Tønsberg, with Myochroidea rufofusca assigned as the type species.[3] This lichen was first described as Biatora rufo-fusca by Martino Anzi in 1860.[4] The name Myochroidea is derived from the Greek word myochrous, which translates to "mouse-coloured." This naming is inspired by the characteristic grey or brown-grey colour of the lichen's body (thallus), reminiscent of the hues found in a mouse's fur.[3]
Description
The thallus of Myochroidea is crust-like and not clearly defined at its edges. It has a texture that can range from wart-like clusters to small, granule-like structures, especially noted in the species M. minutula. These granules are similar in appearance to tiny, angular cysts. The clusters (areoles) can vary in shape from slightly to prominently rounded, sometimes even resembling coral in their complexity. The surface of these lichens is non-glossy, with hues from mouse grey to greyish brown or olive brown, and harbours a trebouxioid (green algal) photobiont.[3]
The reproductive structures (apothecia) of Myochroidea are reddish to blackish brown, and occasionally ochre, in colour. These structures are seated directly on the thallus and may range from flat to significantly rounded, maintaining a matte or slightly shiny appearance. These parts are either not covered in a powdery coating (pruina) or have such a coating so fine that it's only noticeable when moist. The edges of the apothecia are typically slightly raised compared to the central disc, though in older structures, the edges may not be as distinct. The supporting tissue (exciple) surrounding the reproductive discs is either colourless or a pale orange-brown, with the outermost layers blending in colour with the layer above the reproductive cells (epihymenium), composed of strongly gel-like, interweaving and branching fungal filaments. These filaments may be interspersed with small, colourless to pale yellow granules. The underlying tissue layers (hypothecium, subhymenium, and hymenium) are colourless, while the epihymenium may be a pale ochre to brown shade. The filaments (paraphyses) are branched and fuse together, with their tips often brown and slightly enlarged. The spore-producing structures (asci) contain eight spores each and react to iodine by turning dark blue. The spores themselves are simple in form, colourless, and range from spindle-shaped to broadly elliptical.[3]
The structures typically responsible for asexual reproduction (pycnidia) have not been observed in this genus. Chemically, Myochroidea lichens may contain fatty acids, lobaric acid, and xanthones, though some species do not produce any detectable secondary metabolites.[3]