Biology:Racoplaca
Racoplaca is a genus of lichen-forming fungi in the family Strigulaceae.[1] It comprises seven species of foliicolous (leaf-dwelling) lichens.
Taxonomy
The genus Racoplaca was originally established by Antoine Laurent Apollinaire Fée in 1824[2] but was later subsumed within the broader genus Strigula. A 2020 multilocus phylogenetic analysis by Shu-Hua Jiang and colleagues demonstrated that foliicolous (leaf-dwelling) species previously placed in Strigula actually represent six distinct evolutionary lineages. This led to the resurrection of Racoplaca specifically for members of the Strigula subtilissima group. The analysis showed Racoplaca forming a well-supported monophyletic clade characterised by thin, olive-brown to dark olive-green thalli with a metallic sheen, composed of dichotomously branched [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] bordered by thin black lines.[3]
The genus can be distinguished from other related genera in the Strigulaceae by its characteristic thallus morphology, the presence of black borderlines along the lobes, and its [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] perithecial walls that are covered by a thin thallus layer up to the ostiole.[3]
Description
Racoplaca is a genus of crustose lichens that grow on living leaves (foliicolous). The lichen forms a thin, distinctive crust beneath the leaf cuticle, characterised by repeated forking (dichotomous) branches that create a network-like pattern radiating outward. Each branch of this pattern is outlined by a thin black border. The [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] (algal partner) in this symbiotic relationship is from the genus Cephaleuros.[3]
The sexual reproductive structures ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) are prominent and shaped like warts or cones. These are typically covered by a thin layer of the lichen's body (thallus) except at the opening (ostiole), giving them a partially black appearance. The internal fertile tissue ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) is colourless and does not react with iodine-based chemical tests. The spore-producing cells (asci) are club-shaped to oblong, with a short apex ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) and narrow chamber. Each ascus produces eight colourless, two-celled [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] arranged in two rows or irregularly.[3]
The asexual reproductive structures include small black, wart-like to conical chambers (pycnidia) that are either sunken or surface-level. These produce two types of colourless spores (conidia): larger rod-shaped to thread-like ones with two cells and short gel-like appendages at both ends (10–25 μm, never exceeding 50 μm), and smaller, single-celled, spindle to ellipsoid-shaped ones. Chemical analysis using thin-layer chromatography reveals no secondary metabolites.[3]
Species
As of January 2025[update], Species Fungorum (in the Catalogue of Life) accept seven species of Racoplaca:[4]
- Racoplaca macrospora S.H.Jiang, J.C.Wei & Lücking (2021)[5] – China
- Racoplaca maculata (Cooke & Massee) S.H.Jiang, Lücking & J.C.Wei (2020) – Brazil
- Racoplaca maculatoides S.H.Jiang, J.C.Wei & Lücking (2021)[5] – China
- Racoplaca melanobapha (Kremp.) S.H.Jiang, Lücking & J.C.Wei (2020) – pantropical
- Racoplaca subtilissima Fée (1825)
- Racoplaca transversoundulata (Sipman) S.H.Jiang, Lücking & J.C.Wei (2020) – Guyana
- Racoplaca tremens (Müll.Arg.) S.H.Jiang, Lücking & J.C.Wei (2020) – Brazil
References
- ↑ Hyde, K.D.; Noorabadi, M.T.; Thiyagaraja, V.; He, M.Q.; Johnston, P.R.; Wijesinghe, S.N. et al. (2024). "The 2024 Outline of Fungi and fungus-like taxa". Mycosphere 15 (1): 5146–6239 [5225]. doi:10.5943/mycosphere/15/1/25. https://www.researchgate.net/publication/385939154.
- ↑ Fée, A.L.A. (1825) (in fr). Essai sur les cryptogames des écorces exotiques ofcinales. Paris: F. Didot. pp. lxviii, xciv, xcix.
- ↑ 3.0 3.1 3.2 3.3 3.4 Jiang, Shu-Hua; Lücking, Robert; Xavier-Leite, Amanda Barreto; Cáceres, Marcela E.S.; Aptroot, André; Portilla, Carlos Viñas; Wei, Jiang-Chun (2020). "Reallocation of foliicolous species of the genus Strigula into six genera (lichenized Ascomycota, Dothideomycetes, Strigulaceae)". Fungal Diversity 102 (1): 257–291. doi:10.1007/s13225-020-00445-7.
- ↑ "Racoplaca". Species 2000: Leiden, the Netherlands. https://www.catalogueoflife.org/data/taxon/9YM98.
- ↑ 5.0 5.1 Jiang, Shu-Hua; Lücking, Robert; Liu, Hua-Jie; Wei, Xin-Li; Xavier-Leite, Amanda Barreto; Portilla, Carlos Viñas; Ren, Qiang; Wei, Jiang-Chun (2021). "Twelve new species reveal cryptic diversification in foliicolous lichens of Strigula s.lat. (Strigulales, Ascomycota)". Journal of Fungi 8 (1): e2. doi:10.3390/jof8010002. PMID 35049942.
Wikidata ☰ Q116761087 entry
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