Biology:Diplotomma venustum

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Short description: Species of lichen

Diplotomma venustum
Scientific classification edit
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Caliciales
Family: Caliciaceae
Genus: Diplotomma
Species:
D. venustum
Binomial name
Diplotomma venustum
Körb. (1860)
Synonyms[1]

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

The lichen was first formally described as a new species by German lichenologist Gustav Wilhelm Körber in 1860. Körber's Latin [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] 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 [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]. 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

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 ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]). The margin may become weakly [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]. A thin black border (the [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) 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 [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] that commonly dusts the fruiting [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]. 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

Wikidata ☰ {{{from}}} entry