Lithogyalideopsis
Genus of lichens
From Wikipedia, the free encyclopedia
Lithogyalideopsis is a genus of lichen-forming fungi in the family Gomphillaceae.[2] It comprises four rock-dwelling, crust-forming lichens that adhere tightly to siliceous rock in temperate to montane habitats. The genus was established in 2005 when these rock-dwelling species were separated from a related group based on their distinctive reproductive structures. These lichens are characterized by jet-black fruiting discs and unique bristle-like structures that release thread bundles for reproduction, resembling tiny chimney brushes.
| Lithogyalideopsis | |
|---|---|
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Graphidales |
| Family: | Gomphillaceae |
| Genus: | Lithogyalideopsis Lücking, Sérus. & Vězda (2005)[1] |
| Type species | |
| Lithogyalideopsis poeltii (Vězda) Lücking, Sérus. & Vězda (2005) | |
| Species | |
|
L. aterrima | |
Taxonomy
Lithogyalideopsis was circumscribed in 2005 by the lichenologists Robert Lücking, Emmanuël Sérusiaux and Antonín Vězda as part of their major revision of the family Gomphillaceae. They segregated four rock-dwelling (saxicolous) members of the Gyalideopsis aterrima species complex into a separate genus because those lichens share a distinctive Aulaxina-type hyphophore—a minute bristle that releases bundles of propagules (diahyphae). In Lithogyalideopsis the hyphophore is black, needle-like and finishes in a small, hand-shaped (palmate) spray of threads; this architecture differs from the flabellate or simpler setae seen in Gyalideopsis (in the strict sense). Lithogyalideopsis is further characterised by dark, rim-less (lecideine) apothecia and relatively small, transversely-septate spores, features that together mark it out from its parent lineage.[1]
The type species is Lithogyalideopsis poeltii (originally described as Gyalideopsis poeltii). All species are confined to mineral substrates, often damp siliceous rock, and share the almost coal-black fruiting bodies that inspired the generic name (litho- = 'stone').[1]
Description
The thallus of Lithogyalideopsis species is thin, inconspicuous and grey-green to blackish, lacking any erect sterile hairs (setae) that occur in some relatives. Because these species live on bare rock (they are saxicolous rather than leaf-dwelling) the surface is usually matt and finely cracked, without the crystalline sheen common in many foliicolous members of the family. Cells of the green algal photobiont are dispersed through a largely undifferentiated fungal layer, so the thallus has no real cortex.[1]
Sexual structures (apothecia) are minute, circular to slightly irregular discs that sit directly on the thallus. They appear jet-black even when wet and have a true fungal margin (true exciple) but no rim derived from thallus tissue (thalline margin); this margin type is termed lecideine. The proper exciple extends only a short distance below the disc, and the hymenium produces eight very small, colourless ascospores divided by a few transverse walls (septa).[1]
A distinctive diagnostic character is the genus' asexual propagules, or hyphophores. These are stiff, bristle-like black stalks (up to about 1 mm high) whose tip flares into a tiny palmate fan; from that fan radiate 3–5 repeatedly branched threads called diahyphae. The whole apparatus resembles a miniature chimney-brush and releases bundles of hyphae that can start new lichens when they land on suitable rock. This Aulaxina-type hyphophore, together with the black lecideine apothecia and small spores, sets Lithogyalideopsis apart from its parent genus Gyalideopsis.[1]
Habitat and distribution
Lithogyalideopsis is confined to bare rock: every species in the genus is saxicolous, growing as a thin, crustose film on hard, usually siliceous surfaces and producing blackish, lecideine apothecia directly from the stone. Unlike the predominantly leaf-inhabiting members of the family Gomphillaceae, Lithogyalideopsis belongs to a small, non-foliicolous contingent that favours cool, moist rock faces in temperate or tropical-montane belts, with collections extending upward into upper-montane and occasionally subalpine zones where constant humidity prevails.[1]
Species
Species Fungorum accepts four species of Lithogyalideopsis:[3]
- Lithogyalideopsis aterrima (Vězda & Poelt) Lücking, Sérus. & Vězda (2005)
- Lithogyalideopsis poeltii (Vězda) Lücking, Sérus. & Vězda (2005)
- Lithogyalideopsis vivantii (Sérus.) Lücking, Sérus. & Vězda (2005)
- Lithogyalideopsis zelandica (Vězda & Malcolm) Lücking, Sérus. & Vězda (2005)