Biology:Rhizocarpaceae
Rhizocarpaceae[1] is a family of lichen-forming fungi; together with the family Sporastatiaceae it constitutes the order Rhizocarpales[2][3][4] in the Ascomycota, class Lecanoromycetes. These lichens are primarily rock-dwellers that form thin, paint-like crusts tightly attached to stone surfaces, though some species grow as small scales or radiating rosettes. The family includes five genera found mainly in cool to cold regions around the world, where they colonize exposed siliceous and basic rocks in sunny locations. Most species reproduce through small black disc-shaped fruiting bodies that sit flush with or slightly above the crusty surface, and they often contain distinctive chemical compounds that help with identification.
Description
Members of the Rhizocarpaceae are mostly rock-dwelling crustose lichens—forming a thin, paint-like layer that adheres tightly to the substrate—although some species grow as small, scale-like [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] or as [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] rosettes whose lobed margins radiate from a central point. Their upper surface (the [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) is usually present and may be smooth, cracked, or warted and display an array of hues from grey and green to yellow-green when rhizocarpic acid is concentrated near the surface. A few species begin life on the thallus of another lichen (lichenicolous) and may never form a thallus of their own, producing only reproductive bodies on the host. Vegetative propagules such as soralia (powdery eruptions of algal–fungal tissue) or [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] (tiny outgrowths that detach as whole-thallus clones) occur sporadically. The photosynthetic partner is always a green alga with rounded cells (a [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] photobiont).[5]
Sexual reproduction takes place in black apothecia that sit flush with, or project slightly above, the thallus. These [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] may be round, angular, or on rare occasions slit-like; they lack a pale outer rim, a condition termed [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]. The fleshy rim ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) is built from radiating or intertwined fungal threads (hyphae) and may contain crystals visible through polarising light. Inside, the colourless hymenium turns blue with iodine (I+ blue), revealing its amyloid nature. Slender, branching [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] weave through the hymenium, often swelling at their tips and sometimes capped by a dark pigment. The asci are [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]—meaning two wall layers separate during spore release—and carry one to eight ascospores. When mature, the spores are one-celled to [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] (divided by several internal walls), colourless to dark olive-brown, and wrapped in a gelatinous envelope ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]). Asexual reproduction is rare and involves pycnidia, minute flask-shaped structures sunken in the thallus that release cylindrical conidia. Alongside rhizocarpic acid, the medulla may host various depsides, depsidones, and fatty acids that aid species identification through simple chemical spot tests.[5]
Ecology
Collectively, the family's five genera favour siliceous or basic rock, with occasional records from nutrient-poor soils, and are widespread in cool to cold regions where exposed stone provides a stable, sunlit habitat.[5]
Genera
- Catolechia Flot. (1850)[6]
- Epilichen Clem. (1909)
- Haugania E.J.Möller & Timdal (2024)[5] – 2 spp.
- Poeltinula Hafellner (1984)
- Rhizocarpon Ramond ex DC. (1805)
References
- ↑ Hafellner, J. (1984). "Studien in Richtung einer naturlicheren Gliederung der Sammelfamilien Lecanoraceae und Lecideaceae" (in de). Nova Hedwigia 79: 242–366.
- ↑ Bendiksby, Mika; Timdal, Einar (2013). "Molecular phylogenetics and taxonomy of Hypocenomyce sensu lato (Ascomycota: Lecanoromycetes): Extreme polyphyly and morphological/ecological convergence". Taxon 62 (5): 940–956. doi:10.12705/625.18. Bibcode: 2013Taxon..62..940B.
- ↑ Miadlikowska, Jolanta; Kauff, Frank; Högnabba, Filip; Oliver, Jeffrey C.; Molnár, Katalin; Fraker, Emily; Gaya, Ester; Hafellner, Josef et al. (2014). "A multigene phylogenetic synthesis for the class Lecanoromycetes (Ascomycota): 1307 fungi representing 1139 infrageneric taxa, 317 genera and 66 families". Molecular Phylogenetics and Evolution 79: 132–168. doi:10.1016/j.ympev.2014.04.003. PMID 24747130. PMC 4185256. Bibcode: 2014MolPE..79..132M. https://ri.conicet.gov.ar/bitstream/11336/11976/1/CONICET_Digital_Nro.13015.pdf.
- ↑ Lücking, R.; Hodkinson, B.P.; Leavitt, S.D. (2017). "The 2016 classification of lichenized fungi in the Ascomycota and Basidiomycota–Approaching one thousand genera". The Bryologist 119 (4): 361–416. doi:10.1639/0007-2745-119.4.361.
- ↑ 5.0 5.1 5.2 5.3 Fryday, A.; Möller, E.J.; Timdal, E.; Yahr, R.; Cannon, P.; Coppins, B.; Sanderson, N.; Simkin, J. (2024). Rhizocarpales, including Catolechia, Epilichen, Haugania, Poeltinula and Rhizocarpon (Rhizocarpaceae), and Sporastatia and Toensbergia (Sporastatiaceae). Revisions of British and Irish Lichens. 41. p. 2. https://britishlichensociety.org.uk/sites/default/files/Rhizocarpales.pdf.
- ↑ Flotow, J. (1850). "Mikroskopische Flechtenstudien" (in de). Botanische Zeitung 8: 361–369.
Wikidata ☰ Q4353014 entry
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