Xanthoparmelia subverrucigera
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| Xanthoparmelia subverrucigera | |
|---|---|
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Parmeliaceae |
| Genus: | Xanthoparmelia |
| Species: | X. subverrucigera |
| Binomial name | |
| Xanthoparmelia subverrucigera | |
 | |
Xanthoparmelia subverrucigera is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae.[1] It was formally described in 2005 from specimens collected in Embid de la Ribera, Spain. The lichen forms yellowish-green, flat growths measuring 3–5 centimetres across with irregular lobes that adhere closely to the rock surface. Its distinctive features include a wrinkled surface with black-edged margins, small finger-like projections (isidia) that may branch in a coral-like manner, and a brown underside with simple root-like structures. The species has a disjunct distribution, occurring in both southern Europe and southern Africa, and can be distinguished from similar species primarily by its brown lower surface and specific chemical composition.
The lichen was formally described as a new species in 2005 by lichenologists Oscar Blanco, Ana Crespo, and John Elix. The type specimen was collected by the authors in Embid de la Ribera (Zaragoza Province) at an altitude of 510 m (1,670 ft); here, the lichen was found growing on siliceous rocks. It has also been collected from Rhodes Matopos National Park in Zimbabwe. The specific epithet subverrucigera alludes to its resemblance with X. verrucigera.[2]
Description
Xanthoparmelia subverrucigera forms moderately-sized growths measuring 3–5 cm across, which adhere closely to the rock substrate. The thallus consists of lobes that are arranged either side by side or slightly overlapping one another. These lobes are somewhat irregular in shape, branch in an irregular pattern, and measure 1–3 mm in width. The edges of the lobes lack tiny hair-like structures (cilia) and have slightly rounded tips.[2]
The upper surface of the lichen displays a yellow-green colouration and is generally flat without spots (emaculate). While the tips of the lobes appear shiny, the central portions are duller and have a wrinkled texture (rugulose). The lobe margins are characteristically black, particularly at the tips. This lichen does not produce powdery reproductive structures (soredia) but instead develops small, finger-like outgrowths called isidia. These isidia are moderately dense across the thallus, beginning as globular structures before developing into cylindrical projections that occasionally branch in a coral-like manner. The tips of these isidia are covered by a continuous cortical layer (syncorticate) and are typically blackened.[2]
The internal layer (medulla) of the lichen is white. The underside of the thallus ranges from medium to dark brown in colour, becoming black at the tips. Sparse to moderate numbers of simple root-like structures (rhizines) emerge from the lower surface and match its colouration. Sexual reproductive structures (apothecia) and asexual spore-producing structures (pycnidia) have not been observed in this species.[2]
When subjected to chemical spot tests, the cortex is K−, C−, and KC+ (pale yellow). The medulla K+ (yellow to orange), C−, KC+ (red), and P+ (orange). The lichen contains several secondary metabolites, with usnic acid in minor amounts, stictic acid as the major component, and various other substances including constictic, verrucigeric, lusitanic, cryptostictic, connorstictic, and methyl stictic acids in varying concentrations.[2]