Biology:Phylliscum
Phylliscum is a genus of lichen-forming fungi in the family Phylliscaceae. These lichens are small and often appear as tiny dark patches or scales tightly pressed against rock surfaces. They are easily overlooked due to their minute size, but can be found on exposed rocks in dry, sunny locations around the world.
Taxonomy
Phylliscum was originally circumscribed by William Nylander in 1855. In his brief Latin [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]], Nylander characterised the genus by a thallus attached at a central [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]; the [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] occurs as large, scattered, oblong-to-rounded [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]], each enclosed in a tiny gelatinous sheath. The fruiting bodies were said to be "endocarpous" (immersed in the thallus), lacking paraphyses, and producing [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] (non-septate), colourless spores; the hymenial gel gives a wine-red reaction in iodine. He also noted long, needle-shaped conidia (asexual propagules). Nylander included two species: P. endocarpoides and the type species, P. demangeonii.[1]
Phylliscum is placed in the family Phylliscaceae in the 2024 class-wide revision of Lichinomycetes, which reassessed family and genus limits using multilocus DNA data together with diagnostic morphology.[2] In that framework, Phylliscum is grouped with other small, rock-dwelling cyanolichens such as Peltula and Phyllisciella. The paper emphasises that adoption of the revised classification is ongoing in regional floras and databases, so species circumscriptions within the genus may be updated as additional material is sequenced and re-examined.[2]
Description
The lichen body (thallus) in Phylliscum is typically very small and dark brown to blackish, ranging from a tightly attached crust ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) to tiny scale-like patches ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]). The fruiting bodies are usually apothecia: minute [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]-like structures that are often sunk into the thallus (immersed). Inside each apothecium, microscopic sac-like cells (asci) produce many small, colourless spores (ascospores). The photosynthetic partner ([[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]) is a unicellular cyanobacterium, a trait shared with several genera in the Phylliscaceae and relevant to their drought tolerance and ability to resume photosynthesis quickly after wetting.[2]
Habitat and distribution
Species of Phylliscum are chiefly saxicolous (rock-dwelling). They occur on well-lit, often drought-prone surfaces, frequently on calcareous or other mineral substrates. Within the broader family context, such lichens are common members of biological crusts on exposed rock and soil in dry regions, and they can also occupy locally dry microhabitats in otherwise humid climates.[2]
Species
- Phylliscum aotearoa (Henssen & B.Bartlett) M.Schultz & M.Prieto (2024)
- Phylliscum cylindrophorum (Vain.) M.Schultz (2024)
- Phylliscum demangeonii (Moug. & Mont.) Nyl. (1855)
- Phylliscum japonicum Zahlbr. (1927)[3]
- Phylliscum laatokkaense (Vain.) M.Schultz & M.Prieto (2024)
- Phylliscum microphyllum Asahina (1931)
- Phylliscum neglectum (Henssen) M.Schultz & M.Prieto (2024)
- Phylliscum permiscens (Nyl.) M.Schultz & M.Prieto (2024)
- Phylliscum rhodostictum (Taylor) M.Schultz & M.Prieto (2024)
- Phylliscum vermiformis M.Schultz & Büdel (2000)[4]
References
- ↑ Nylander, W. (1855). "Essai d'une nouvelle classification des lichens, (second mémoire)" (in fr). Mémoires de la Société Impériale des Sciences Naturelles de Cherbourg 3: 161–202 [166]. https://www.biodiversitylibrary.org/page/3862176.
- ↑ 2.0 2.1 2.2 2.3 Prieto, M.; Wedin, M.; Schultz, M. (2024). "Phylogeny, evolution and a re-classification of the Lichinomycetes". Studies in Mycology 109: 595–655. doi:10.3114/sim.2024.109.09. PMID 39717657.
- ↑ Zahlbruckner, A. (1927). "Additamenta ad Lichenographiam Japoniae" (in la). The Botanical Magazine, Tokyo 41: 313–364.
- ↑ Schultz, M.; Porembski, S.; Büdel, B. (2000). "Diversity of rock-inhabiting cyanobacterial lichens: studies on granite inselbergs along the Orinoca and the Guyana region". Plant Biology 2 (2): 482–495. doi:10.1055/s-2000-5951.
<ref> tag with name "Species Fungorum synonymy" defined in <references> is not used in prior text.Wikidata ☰ Q7188648 entry
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