Cladonia didyma
{{Short description|Species of lichen}}
{{Speciesbox
|image = Cladonia didyma (Fée) Vainio 80437.jpg
|genus = Cladonia
|species = didyma
|authority = (Fée) Vain (1887){{cite web |title=Taxonomy browser (Cladonia didyma) |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=174056 |website=www.ncbi.nlm.nih.gov |access-date=7 May 2024}}
}}
Cladonia didyma is a fruticose lichen, commonly known as southern soldiers, belonging to the family Cladoniaceae, which include fungal symbionts under the Ascomycota phylum with characteristic red ascocarps containing sexually reproductive asci.{{Cite journal |last1=Steinová |first1=Jana |last2=Škaloud |first2=Pavel |last3=Yahr |first3=Rebecca |last4=Bestová |first4=Helena |last5=Muggia |first5=Lucia |date=2019-05-01 |title=Reproductive and dispersal strategies shape the diversity of mycobiont-photobiont association in Cladonia lichens |url=https://www.sciencedirect.com/science/article/pii/S1055790317307170 |journal=Molecular Phylogenetics and Evolution |volume=134 |pages=226–237 |doi=10.1016/j.ympev.2019.02.014 |pmid=30797939 |hdl=11368/2951192 |issn=1055-7903|hdl-access=free }}
Initially named Scyphophorus didymus (Fée 1824), it was later reclassified into Cladonia didyma in 1887.{{Cite book |last1=Societas pro Fauna et Flora Fennica |url=https://www.biodiversitylibrary.org/item/28290 |title=Acta Societatis pro Fauna et Flora Fennica |last2=Fennica |first2=Societas pro Fauna et Flora |date=1887 |publisher=Societas |volume=v. 4 (1887) |location=Helsinki}} Its namesake is described as deriving from the ancient Greek κλᾰ́δος (kládos) meaning 'branching' and Δίδυμος (didymus) describing 'bunched', 'clustered' or 'paired'{{Cite web |last=Charters |first=Michael L. |title=Latin and Greek Meanings and Derivations. An Annotated Dictionary of Botanical and Biographical Etymology |url=https://www.calflora.net/botanicalnames/pageD.html |access-date=2024-04-26 |website=California Plant Names}} indicative of the branched like structures characteristic of the Cladonia genus and the often observed clusters of C. didyma found among various other Cladonia spp. or other C. didyma variants.{{Cite journal |last1=Gumboski |first1=Emerson Luiz |last2=Eliasaro |first2=Sionara |date=2012 |title=Espécies de Cladonia P. Browne (Cladoniaceae, Ascomycota) dos Supergrupos Cocciferae, Crustaceae e Perviae em restingas e costões rochosos dos estados do Paraná e de Santa Catarina, Brasil |url=https://www.scielo.br/j/abb/a/cgsFTFfRVSJPStBVXK8T7nG/?lang=pt |journal=Acta Botanica Brasilica |volume=26 |issue=3 |pages=619–631 |doi=10.1590/S0102-33062012000300011 |issn=0102-3306|doi-access=free }}{{Cite journal |last1=Fraga |first1=Carlos Augusto Vidigal |last2=Gumboski |first2=Emerson Luiz |date=2017 |title=The genus Cladonia (Lichenized Ascomycota) from Restinga vegetation of Espírito Santo state, Brazil: Supergroups Cladonia and Cocciferae |url=https://www.scielo.br/j/rod/a/hxfyqtBvnp3QcpWjhd3Mywm/?lang=en |journal=Rodriguésia |language=en |volume=68 |issue=5 |pages=1951–1962 |doi=10.1590/2175-7860201768526 |issn=0370-6583}}
Physiology
Species in the Cladonia genus have distinct, easily identifiable characteristics.{{Cite web |title=University of Florida Natural Area Teaching Laboratory |url=https://natl.ifas.ufl.edu/biota/lichens.php |access-date=2024-05-06 |website=natl.ifas.ufl.edu}} However, species identification generally requires assessment of their chemical and metabolic properties due to high morphological similarity among species, and wide occurrence of environmentally contextual within species variations.{{Cite journal |last1=Stenroos |first1=Soili |last2=Pino-Bodas |first2=Raquel |date=2019 |title=Phylogeny of the family Cladoniaceae (Lecanoromycetes, Ascomycota) based on sequences of multiple loci |url=https://onlinelibrary.wiley.com/doi/10.1111/cla.12363 |journal=Cladistics |language=en |volume=35 |issue=4 |pages=351–384 |doi=10.1111/cla.12363 |pmid=34633698 |hdl=10261/247495 |issn=0748-3007|hdl-access=free }}{{Cite journal |last=Stenroos |first=Soili |date=1986 |title=The family Cladoniaceae in Melanesia. 2. Cladonia section Cocciferae |url=https://www.jstor.org/stable/23726187 |journal=Annales Botanici Fennici |volume=23 |issue=3 |pages=239–250 |jstor=23726187 |issn=0003-3847}}
The upper surface of the primary thallus has a smooth, green to gray cortex with a slight sheen. The structure includes concealed squamules 0.7–2.0 mm long and 0.5–1.5 mm wide which can be either lobed or laciniate and lack soredia. Conversely the bottom surface lacks a cortex and is white and flat.
The podetia (secondary thallus) is branched, and ranges from white to gray, 0.5 –2.4 cm tall, outer diameter of 0.5–1.5 mm. Its surface is granulose with squamulose features around the base and lacks soredia. Variation of micro physiological features include presence or absence of a medulla or cortex, and surface textures that can be grooved, smooth, or velvety. When a medulla is present, its sterome is 100–142 μm thick and is brown or gray in color.
The apex of the podetia contains either a single or clustered grouping of convex, margin-less apothecia ranging from 2.5 - 0.3 mm wide. The color ranges from orange to scarlet red and changes to blue in response to iodine. Ascospores can be either fusiform or oblong.
Secondary metabolites
Barbatic, thamnolic, and didymic acids are among the most common metabolites produced by C. didyma. Other known compounds that have been observed include condidymic, subdidymic, and decarboxythamnolic acids, while others have yet to be characterized. Among the many phenotypes of C. didyma, two major chemotypes have been defined by the presence of either didymic or thamnolic acid and are observed within different habitat types.
Analysis of C. didyma metabolites has found antioxidant compounds as well as others within chemical families associated with defense responses related to oxidative stress and UV exposure.{{Cite journal |last1=Núñez-Arango |first1=Lissy M. |last2=Rojas |first2=José L. |last3=Valencia-Islas |first3=Norma A. |last4=Cerbón |first4=Marco |last5=González-Sánchez |first5=Ignacio |date=2023-11-06 |title=Metabolites from the Andean paramo lichen Cladonia cf. didyma and their effect as photoprotective and antioxidant agents |url=https://www.tandfonline.com/doi/full/10.1080/14786419.2023.2272028 |journal=Natural Product Research |language=en |pages=1–9 |doi=10.1080/14786419.2023.2272028 |pmid=37932254 |issn=1478-6419|doi-access=free }} Experimental tests on these compounds revealed their potential uses in sun protection and regulation of free radicals.
Habitat and distribution
Cladonia didyma has a wide distribution and can be found on nearly every continent and oceanic region{{Cite journal |last=Vain |first=Fée |date=2023 |title=Cladonia didyma |url=https://doi.org/10.15468/39omei |access-date=2024-04-26 |website=GBIF Backbone Taxonomy |publisher=GBIF Secretariat|doi=10.15468/39omei }} under various environmental conditions, at sea level and altitudes as high as 3400 meters, and habitats ranging from mesic to xeric forests. Often found growing on dying or decaying trees among other mosses and lichens, but has also been observed to persist within sandy soils or growing on rocks, and has been found in mycorrhizal sequencing analysis of epiphytic orchids.{{Cite journal |last1=Herrera |first1=Paulo |last2=Suárez |first2=Juan Pablo |last3=Sánchez-Rodríguez |first3=Aminael |last4=Molina |first4=M. Carmen |last5=Prieto |first5=María |last6=Méndez |first6=Marcos |date=2019-06-01 |title=Many broadly-shared mycobionts characterize mycorrhizal interactions of two coexisting epiphytic orchids in a high elevation tropical forest |url=https://www.sciencedirect.com/science/article/pii/S1754504818300187 |journal=Fungal Ecology |volume=39 |pages=26–36 |doi=10.1016/j.funeco.2018.11.003 |bibcode=2019FunE...39...26H |issn=1754-5048}}