Cladonia cariosa is a species of fruticose lichen in the family Cladoniaceae. The species is characterised by its thick, tongue-shaped basal scales and upright grey-green stalks that lack the cup-like structures found in many related lichens, instead being topped with large chocolate-brown fruiting bodies. It has a cosmopolitan distribution and commonly grows on soil in both calcium-rich and calcium-poor sites across northern North America. The lichen is also known by the common names split-peg lichen and split-peg soldiers.
The lichen was originally described by Swedish lichenologist Erik Acharius in 1799 as Lichen cariosus. Acharius described the species as having cartilaginous thalli with small, somewhat rounded lobes that were crenulate (finely scalloped) along the margins. The upper surface was whitish-green with scattered, wartlike protuberances, whilst the lower surface was divided and bore purple apothecia (fruiting bodies). The species was noted to have a distinctive habitat preference, being found on sterile ground in camps.
In his original description, Acharius provided the habitat note Ob scyphos nullos vel faltem omnino imperfectos inter Scyphophoros locum obtinere non potest nec debet ('Because it has no cups or at least completely imperfect ones, it cannot and should not obtain a place among the Scyphophoros'), indicating his taxonomic reasoning for not placing it within the cup lichen group. He observed simple structures with a single terminal tubercle. The species epithetcariosus refers to the decayed or carious appearance of the lichen, reflecting the wartlike texture of its upper surface that Acharius noted in his original description.[2]Kurt Sprengel transferred the taxon to the genus Cladonia in 1827. In his treatment, Sprengel provided additional details about the podetia , describing them as whitish with a carious-cancellate (decayed and lattice-like) surface texture, and noted that the apothecia were dilated and divided at the apex.[3]
Common names given to this species include the "split-peg lichen" and "split-peg soldiers".[4]
Description
The primary squamules of Cladonia cariosa are thick and typically tongue-shaped, measuring 1–3 by 0.5–2mm across, and sometimes develop teeth or slight lobes . The upright stalks (podetia) are grey to grey-green in colour, with a torn and fissured surface that may branch once or twice but lacks the cup-like structures found in many other Cladonia species. These podetia can reach up to 30mm in height and have a broken, areolate surface texture without powdery soredia. The stalks are topped with large, chocolate-brown apothecia.[4]
Two distinct chemical forms are commonly found in North America: one contains both fumarprotocetraric acid and atranorin (giving a red reaction with PD solution and yellow with K solution on the white lower surface of the squamules), whilst the other contains only atranorin (showing no reaction or pale yellow with PD, and yellow with K).[4]
Cladonia peziziformis is somewhat similar in appearance, but can be distinguished by its lack of atroanorin (resulting in a C− spot test), the lighter brown colours of its apothecia, and its greener podetia.
Habitat and distribution
Cladonia cariosa is a widespread lichen with a cosmopolitan distribution.[5] It grows directly on soil in calcium-rich and calcium poor-sites,[4] and also in sun-exposed sandy soil.[5] It is widely distributed in northern North America.[4][5]
1 2 3 4 5 Brodo, Irwin M.; Sharnoff, Sylvia Duran; Sharnoff, Stephen (2001). Lichens of North America. Yale University Press. pp.242–243. ISBN978-0300082494.
1 2 3 McMullin, R. Troy (2023). Lichens. The Macrolichens of Ontario and the Great Lakes Region of the United States. Firefly Books. p.134. ISBN978-0-228-10369-1.
↑ Černajová, Ivana; Škaloud, Pavel (2019). "The first survey of Cystobasidiomycete yeasts in the lichen genus Cladonia; with the description of Lichenozyma pisutiana gen. nov., sp. nov". Fungal Biology. 123 (9): 625–637. doi:10.1016/j.funbio.2019.05.006.
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