Leimonis
| Leimonis | |
|---|---|
| |
| Leimonis erratica | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Pilocarpaceae |
| Genus: | Leimonis R.C.Harris (2009) |
| Type species | |
| Leimonis erratica (Körb.) R.C.Harris & Lendemer (2009)
| |
| Species | |
Leimonis is a small genus of lichen-forming fungi in the family Pilocarpaceae. It comprises two species.[1] These lichens form pale to dark grey crusts on rocks and weathered wood, producing numerous tiny black fruiting bodies dotted across the surface. Both species act as pioneer colonisers of bare surfaces and are found throughout temperate regions worldwide.
Taxonomy
[edit]The genus was circumscribed by lichenologist Richard C. Harris in 2009. The generic name Leimonis comes from the Greek word leimōn ('field') and alludes to the fact that the type species, L. erratica, is often found in open habitats, especially on long-abandoned fields that are still in the early phases of ecological succession.[2] A second species, L. lynceola, was added to the genus in 2017; it was originally described as a species of Lecidea.[3]
Description
[edit]The thallus of Leimonis forms a pale- to dark-grey crust on non-calcareous rock, occasionally appearing on old, weathered timber. Under favourable conditions it develops as a more or less continuous skin that cracks into small angular patches (rimose–areolate); in windswept or nutrient-poor sites it may be reduced to tiny scattered areoles and the black, tree-like (dendritic) prothallus that borders them. The partnership's algal component is a single-celled green alga of the chlorococcoid type, and no lichen secondary metabolites have been detected in chemical spot tests. Numerous minute, black apothecia—disc-shaped fruiting bodies that sit directly on the thallus—dot the surface. They are 0.2–0.5 mm across, slightly pinched at the base and usually flat with a low rim of the same colour, though the rim can disappear as the disc becomes swollen with age.[2]
Microscopic sections show the apothecial rim (exciple) is green externally and pale inside, its tissue built from radiating, branched hyphae locked together. Beneath the spore layer (hymenium) lies a brown hypothecium that sends faint pigment strands into the rim, while the uppermost layer epihymenium) is green and turns red in nitric acid (N+ red). The hymenium itself is nearly colourless, traversed by slender, sparsely branched paraphyses and containing asci of the Pilocarpaceae type—elongate sacs that each release eight ascospores. These spores are simple (lacking septa), narrowly ellipsoid and small, measuring 6–9 × 2.5–3.5 μm. Asexual reproduction occurs in embedded, black pycnidia about 0.1 mm wide whose green walls consist of roughly spherical cells; they produce colourless, oblong conidia 4–6 × 1.5–2 μm.[2]
Habitat and distribution
[edit]Leimonis comprises two species that behave as pioneer colonizers on bare rock and decaying wood and are widespread throughout the temperate regions of the globe.[4]
Species
[edit]Species Fungorum accepts two species in Leimonis:[5]
- Leimonis erratica (Körb.) R.C.Harris & Lendemer (2009)[2]
- Leimonis lynceola (Th.Fr.) Aptroot (2017)[3]
References
[edit]- ^ Hyde, K.D.; Noorabadi, M.T.; Thiyagaraja, V.; He, M.Q.; Johnston, P.R.; Wijesinghe, S.N.; et al. (2024). "The 2024 Outline of Fungi and fungus-like taxa". Mycosphere. 15 (1): 5146–6239 [5253]. doi:10.5943/mycosphere/15/1/25.
- ^ a b c d Harris, R.C. (2009). "Four novel lichen taxa in the lichen biota of eastern North America". Opuscula Philolichenum. 6: 149–156.
- ^ a b Aptroot, A. (2017). "Nomenclatural novelties" (PDF). Index Fungorum. 331: 1.
- ^ Kantvilas, G. (2024). Salas, M.F. de (ed.). "Leimonis, version 2024:1". Flora of Tasmania Online. Hobart: Tasmanian Herbarium, Tasmanian Museum and Art Gallery. Retrieved 29 June 2025.
- ^ "Leimonis". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 29 June 2025.