Diplotomma venustum
| Diplotomma venustum | |
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Scientific classification 
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| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Caliciales |
| Family: | Caliciaceae |
| Genus: | Diplotomma |
| Species: | D. venustum
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| Binomial name | |
| Diplotomma venustum Körb. (1860)
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| Synonyms[1] | |
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List
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Diplotomma venustum is a species of saxicolous (rock-dwelling) crustose lichen in the family Caliciaceae.[2] It is widely distributed, having been recorded from all continents, where it grows on calcareous rocks.[3]
Taxonomy
[edit]The lichen was first formally described as a new species by German lichenologist Gustav Wilhelm Körber in 1860. Körber's Latin diagnosis emphasised the firmly attached, granular-powdery thallus with very fine wrinkling, and the mostly solitary apothecia that are immersed in the thallus when young but become convex with a black disc. He characterised the colourless ascospores as ellipsoidal to spindle-shaped with 4 cross-walls (4-septate) and noted they turn sooty-brown with age. The species was described from limestone and dolomite rocks in mountainous regions of central Europe, including collections from Germany, Austria, and the Carpathian Mountains.[4]
Description
[edit]Diplotomma venustum forms a crust-like thallus that is tightly attached to the substrate (crustose) and often broken up by numerous irregular cracks and fissures (rimose). The margin may become weakly lobed. A thin black border (the prothallus) is sometimes visible around the thallus. The upper surface is chalky white, grey, or ochre-tinged and lacks powdery vegetative propagules. The interior (medulla) is white and contains abundant needle-shaped crystals of calcium oxalate; these crystals also generate the fine white pruina that commonly dusts the fruiting discs. Under ultraviolet light the thallus does not fluoresce (UV-), and standard spot tests on the thallus and medulla are negative in North American material (K-, P-, C-); outside North America, some collections react K+ (yellow turning red) and P+ (yellow-orange), reflecting the presence of norstictic and connorstictic acids in the medulla.[5]
References
[edit]- ^ "GSD Species Synonymy. Current Name: Diplotomma venustum Körb., Parerga lichenol. (Breslau) 2: 179 (1860)". Species Fungorum. Retrieved 16 October 2025.
- ^ "Diplotomma venustum Körb". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 16 October 2025.
- ^ Kantvilas, Gintaras. "Diplotomma". Flora of Tasmania Online. Hobart: Tasmanian Herbarium, Tasmanian Museum and Art Gallery. Retrieved 16 October 2025.
- ^ Körber, Gustav Wilhelm (1865). Parerga lichenologica. Ergänzungen zum Systema lichenum Germaniae (in German). Vol. 2. Breslau: E. Trewendt. p. 179. doi:10.5962/bhl.title.87905.
- ^ Nash III, Thomas H.; Gries, Corinna; Bungartz, Frank, eds. (2007). "Romjularia". Lichen Flora of the Greater Sonoran Desert Region. Vol. 3. Tempe: Lichens Unlimited, Arizona State University.