{{Short description|Genus of lichen-forming fungi}} {{Use dmy dates|date=June 2025}} {{Use Oxford spelling|date=June 2025}} {{Automatic taxobox | image = Thelocarpon laureri 1645882100.jpg | image_caption = ''Thelocarpon laureri'' | taxon = Thelocarpon | authority = Nyl. (1853) | type_species = ''Thelocarpon laureri'' | type_species_authority = (Flot.) Nyl. (1854) | subdivision_ranks = Species | subdivision = | synonyms_ref = <ref name="Species Fungorum synonymy"/> | synonyms = {{collapsible list|bullets=on |''Ahlesia'' {{au|Fuckel (1870)}} |''Athelium'' {{au|Nyl. (1886)}} |''Cyanocephalium'' {{au|Zukal (1893)}} |''Kelleria'' {{au|Tomin (1926)}} |''Metanectria'' {{au|Sacc. (1878)}} |''Mycothelocarpon'' {{au|Cif. & Tomas. (1953)}} |''Sphaeropsis'' {{au|Flot. (1847)}} |''Thelocarponomyces'' {{au|Cif. & Tomas. (1953)}} |''Thelocarpum'' {{au|Clem. (1909)}} |''Thelococcum'' {{au|Nyl. (1888)}} |''Thelomphale'' {{au|Flot. (1863)}} }} }}
'''''Thelocarpon''''' is a genus of lichen-forming fungi in the family Thelocarpaceae.<ref name="Wijayawardene et al. 2020"/> The genus was established in 1853 by the Finnish lichenologist William Nylander, who distinguished it from related genera by its warted thallus structure, many-spored asci, and the distinctive violet-blue staining reaction of its fruiting body gel when treated with iodine. These tiny lichens form small, wart-like bumps on soil, wood, and plant debris, often covered with a distinctive bright yellow powdery coating. The genus includes about 30 species found worldwide, many of which produce unusually large numbers of ascospores—sometimes over 300 per spore sac.
==Taxonomy==
The genus was circumscribed in 1853 by the Finnish lichenologist William Nylander. He established the genus to accommodate lichens with a whitish thallus composed of {{lichengloss|granular}}, clustered wart-like structures that sit above {{lichengloss|papillae}} and are perforated by mostly subtle pores, each containing a single pale, somewhat enlarged apothecium (fruiting body). He characterised the genus by its cylindrical-spindle-shaped, many-spored asci containing 24–80 or more ascospores per ascus, with the spores being pale yellow, ellipsoid, frequently single-celled. Nylander noted the presence of slender, very abundant paraphyses and observed that the genus was related to ''Endocarpon'', commenting that it belonged to the tribe Endocarpeae. He distinguished ''Thelocarpon'' from the previously described ''Sphaeropsis'' by its different thallus characteristics, proposing the new genus name after noting that the mucilaginous hymenium was stained violet-blue by iodine and potassium iodide.<ref name="Nylander 1853"/>
In a 1966 monograph of the genus, George Salisbury treated ''Thelocarpon'' in a relatively narrow sense, accepting 13 species and reviewing several generic names that had at various times been used for segregates now associated with the genus, including ''Thelococcum'', ''Athelium'', and ''Alinocarpon''. He also noted that the genus had long been difficult to classify, having been placed by different authors near the Hypocreaceae, the Acarosporaceae, or in its own family, Thelocarpaceae. Salisbury had earlier divided the genus into sections based on the presence or absence of an algal sheath, but in his 1966 revision he abandoned that arrangement, arguing that it relied too heavily on degree of lichenization rather than natural relationships. He instead organized the species chiefly by the morphology of the paraphyses together with the development of the algal sheath.<ref name="Salisbury 1966"/>
==Description==
''Thelocarpon'' species are minute lichens whose thallus, when present, wraps around the developing fruit-body so that the two form a tiny, wart-like mound. In many species this sheath is so reduced that the ascoma appears to sit naked on the substrate; a few taxa instead develop a thin, scaly crust. The photosynthetic partner, when there is one, is a single-celled green alga, but some species lack algae altogether and rely on absorbed nutrients.<ref name="Cannon et al. 2025"/>
The sexual fruiting bodies occur in two basic forms. Most species produce perithecia: minute, globose or flask-shaped flasks that open through a pore, while others form apothecia that resemble short cylinders or low discs with the spore layer exposed. Either type may sit on the surface or be slightly sunk into it, and the exterior is often dusted with a bright yellow powdery coating ({{lichengloss|pruina}}) produced by pulvinic acid pigments. The outer wall ({{lichengloss|exciple}}) is pale or colourless and contains no dark melanins. Inside, the {{lichengloss|hamathecium}} consists of a mesh of delicate, branching filaments—paraphyses, {{lichengloss|periphysoids}} and {{lichengloss|periphyses}}—that are embedded in a jelly. This jelly is diagnostic: it stays clear in iodine solution or, at higher iodine strength, turns red and then deep blue after potassium iodide pretreatment, a reaction called hemiamyloidy. The asci are bottle- to tube-shaped, sometimes with a slightly thickened tip ({{lichengloss|tholus}}), and each sac bursts to release a crowd of ascospores—anywhere from a dozen to more than 300. The spores are tiny, colourless, mostly one-celled and usually contain a pair of oil droplets.<ref name="Cannon et al. 2025"/>
Asexual reproduction takes place in equally small pycnidia, flask-like structures that share the same wart-like cover as the perithecia. These generate cylindrical or short-ellipsoid conidia that are usually single-celled but may occasionally show up to two cross-walls. Many ''Thelocarpon'' species manufacture pulvinic acid derivatives such as vulpinic acid and pulvinic dilactone. When these pigments are secreted to the surface they create the conspicuous yellow pruina, but in some taxa they are locked within the upper exciple instead. The combination of multispored asci, vivid yellow chemistry and the warted habit makes the genus distinctive among crustose lichens found on nutrient-poor soils, wood and decaying plant debris.<ref name="Cannon et al. 2025"/>
==Species== {{As of|2025|June}}, Species Fungorum (in the Catalogue of Life) accept 29 species of ''Thelocarpon''.<ref name="CoL_CF7XP"/> {{div col}} *''Thelocarpon actonii'' {{au|P.F.Cannon & Coppins (2025)}} *''Thelocarpon albidum'' {{au|Nyl. (1853)}}<ref name="Nylander 1853"/> *''Thelocarpon algicola'' {{au|Groenh. (1954)}}<ref name="Groenhart 1954"/> *''Thelocarpon andicola'' {{au|Flakus & Kukwa (2014)}}<ref name="Flakus & Kukwa 2014"/> *''Thelocarpon citrum'' {{au|(Wallr.) Rossman (1999)}}<ref name="Rossman 1999"/> *''Thelocarpon coccosporum'' {{au|Lettau (1955)}}<ref name="Lettau 1955"/> *''Thelocarpon cyaneum'' {{au|Olech & Alstrup (1990)}}<ref name="Olech & Astrum 1990"/> *''Thelocarpon epibolum'' {{au|Nyl. (1866)}}<ref name="Nylander 1866"/> *''Thelocarpon immersum'' {{au|Fryday (2020)}}<ref name="Spribille et al. 2020"/> *''Thelocarpon imperceptum'' {{au|(Nyl.) Mig. (1927)}} *''Thelocarpon impressellum'' {{au|Nyl. (1867)}}<ref name="Nylander 1867"/> *''Thelocarpon intermediellum'' {{au|Nyl. (1865)}}<ref name="Nylander 1865"/> *''Thelocarpon laureri'' {{au|(Flot.) Nyl. (1854)}}<ref name="Nylander 1855"/> *''Thelocarpon lichenicola'' {{au|(Fuckel) Poelt & Hafellner (1975)}}<ref name="Poelt & Hafellner 1975"/> *''Thelocarpon macchiae'' {{au|Nimis, Poelt & Puntillo (1994)}}<ref name="Nimis et al. 1994"/> *''Thelocarpon magnussonii'' {{au|G.Salisb. (1953)}}<ref name="Salisbury 1953"/> *''Thelocarpon microsporum'' {{au|van den Boom (2016)}}<ref name="Van den Boom 2016"/> *''Thelocarpon nigrum'' {{au|Aptroot & K.H.Moon (2009)}}<ref name="Moon & Aptroot 2009"/> *''Thelocarpon olivaceum'' {{au|B.de Lesd. (1914)}}<ref name="Bouly de Lesdain 1914"/> *''Thelocarpon opertum'' {{au|J.C.David & Coppins (1997)}}<ref name="David & Coppins 1997"/> *''Thelocarpon pallidum'' {{au|G.Salisb. (1953)}}<ref name="Salisbury 1953"/> *''Thelocarpon palniense'' {{au|D.D.Awasthi & Kr.P.Singh (1975)}}<ref name="Awasthi & Singh & 1975"/> *''Thelocarpon robustum'' {{au|Eitner (1901)}}<ref name="Eitner 1901"/> *''Thelocarpon sandwicense'' {{au|H.Magn. (1955)}}<ref name="Magnusson 1955"/> *''Thelocarpon saxicola'' {{au|(Zahlbr.) H.Magn. (1935)}} *''Thelocarpon sphaerosporum'' {{au|H.Magn. (1935)}} *''Thelocarpon strasseri'' {{au|Zahlbr. (1902)}}<ref name="Zahlbruckner 1902"/> *''Thelocarpon subantarcticum'' {{au|Øvstedal (2001)}}<ref name="Øvstedal & Gremmen 2001"/> *''Thelocarpon superellum'' {{au|Nyl. (1865)}}<ref name="Nylander 1865"/> *''Thelocarpon triseptatum'' {{au|Aptroot & M.Cáceres (2016)}}<ref name="da Silva Cáceres & Aptroot"/> – Brazil {{div col end}}
==References== {{Reflist|colwidth=30em|refs=
<ref name="Awasthi & Singh & 1975">{{cite journal |last1=Awasthi |first=D.D. |last2=Singh |first2=K.P. |year=1975 |title=Three new taxa of lichens from Palni Hills, India |journal=Geophytology |volume=5 |issue=1 |pages=39–42}}</ref>
<ref name="Bouly de Lesdain 1914">{{cite book |last=Bouly de Lesdain |first=Maurice |year=1914 |title=Recherches sur les lichens des environs de Dunkerque, 1er supplément |trans-title=Research on the lichens of the surroundings of Dunkirk, 1st supplement |publisher=Société dunkerquoise pour l'encouragement des sciences, des lettres et des arts |page=149 |language=fr}}</ref>
<ref name="Cannon et al. 2025">{{cite book |last1=Cannon |first1=P. |last2=Coppins |first2=B. |last3=Simkin |first3=J. |year=2025 |title=Thelocarpales, including Sarcosagium and Thelocarpon (Thelocarpaceae) |series=Revisions of British and Irish Lichens |volume=48 |pages=1–10 [3] |url=https://britishlichensociety.org.uk/sites/default/files/Thelocarpales.pdf}}</ref>
<ref name="CoL_CF7XP">{{Catalogue of Life |id=CF7XP |title=''Thelocarpon'' |access-date=20 June 2025}}</ref>
<ref name="da Silva Cáceres & Aptroot">{{cite journal |last1=da Silva Cáceres |first1=Marcela Eugenia |last2=Aptroot |first2=André |title=First inventory of lichens from the Brazilian Amazon in Amapá State |journal=The Bryologist |volume=119 |issue=3 |year=2016 |doi=10.1639/0007-2745-119.3.250 |pages=250–265 |url=https://www.researchgate.net/publication/307904602}}</ref>
<ref name="David & Coppins 1997">{{cite journal |last1=David |first1=J.C. |last2=Coppins |first2=B.J. |title=''Thelocarpon opertum'' (Acarosporaceae), a new species from the British Isles |journal=The Lichenologist |volume=29 |issue=3 |year=1997 |doi=10.1006/lich.1996.0070 |pages=291–295}}</ref>
<ref name="Eitner 1901">{{cite journal |last=Eitner |first=E. |year=1901 |title=Zweiter Nachtrag zur schlesischen Flechtenflora |trans-title=Second supplement to the Silesian lichen flora |journal=Jahresbericht der Schlesischen Gesellschaft für Vaterländische Kultur |volume=78 |pages=5–27 [13] |language=de}}</ref>
<ref name="Flakus & Kukwa 2014">{{cite journal |last1=Flakus |first1=Adam |last2=Kukwa |first2=Martin |title=The first squamulose ''Thelocarpon'' species (Thelocarpaceae, Ascomycota) discovered in the biological soil crusts in the Bolivian Andes |journal=Phytotaxa |volume=175 |issue=5 |year=2014 |doi=10.11646/phytotaxa.175.5.7 |page=281}}</ref>
<ref name="Groenhart 1954">{{cite journal |last=Groenhart |first=P. |year=1954 |title=Malaysian lichens–IV |journal=Reinwardtia |volume=2 |issue=3 |pages=385–402}}</ref>
<ref name="Lettau 1955">{{cite journal |last=Lettau |first=G. |year=1955 |title=Flechten aus Mitteleuropa X |trans-title=Lichens of Middle Europe X |journal=Feddes Repertorium Specierum Novarum Regni Vegetabilis |volume=57 |pages=1–94 [75] |language=de}}</ref>
<ref name="Magnusson 1955">{{cite journal |last=Magnusson |first1=A.H. |year=1955 |title=A catalogue of the Hawaiian Lichens |journal=Arkiv för Botanik |series=2 |volume=3 |issue=10 |pages=223–402}}</ref>
<ref name="Moon & Aptroot 2009">{{cite journal |last1=Moon |first1=K.H. |last2=Aptroot |first2=A. |year=2009 |title=Pyrenocarpous lichens in Korea |journal=Bibliotheca Lichenologica |volume=99 |pages=297–314}}</ref>
<ref name="Nimis et al. 1994">{{cite journal |last1=Nimis |first1=P.L. |last2=Poelt |first2=J. |last3=Tretiach |first3=M. |last4=Ottonello |first4=D. |last5=Puntillo |first5=D. |last6=Vezda |first6=A. |year=1994 |title=Contributions to lichen floristics in Italy. VII – The lichens of Marettimo (Egadi Islands, Sicily) |journal=Bulletin de la Société Linnéenne de Provence |volume=45 |pages=247–262 [259] |url=https://www.researchgate.net/publication/235224428}}</ref>
<ref name="Nylander 1853">{{cite journal |last=Nylander |first=W. |year=1853 |title=Lichenes algerienses novi |trans-title=New Algerian lichens |journal=Annales des Sciences Naturelles. Botanique |series=3 |volume=20 |pages=315–320 |language=la |url=https://www.biodiversitylibrary.org/page/41553212}}</ref>
<ref name="Nylander 1855">{{cite journal |last=Nylander |first=W. |year=1855 |title=Essai d'une nouvelle classification des lichens, (second mémoire) |trans-title=Essay on a new classification of lichens, (second memoir) |journal=Mémoires de la Société Impériale des Sciences Naturelles de Cherbourg |volume=3 |pages=161–202 [191] |language=la}}</ref>
<ref name="Nylander 1865">{{cite journal |last=Nylander |first=W. |year=1865 |title=Circa Thelocarpa Europaea notula |trans-title=A note on European ''Thelocarpon'' |journal=Flora |volume=48 |pages=260–262 |language=la |url=https://www.biodiversitylibrary.org/page/56370}}</ref>
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<ref name="Nylander 1867">{{cite journal |last=Nylander |first=W. |year=1867 |title=Addenda nova ad lichenographiam Europaeam. Cont. IV |trans-title=New additions to European lichenography. Continuation IV |journal=Flora |volume=50 |pages=177–180 |language=la}}</ref>
<ref name="Olech & Astrum 1990">{{cite journal |last1=Olech |first1=M. |last2=Alstrup |first2=V. |year=1990 |title=''Thelocarpon cyaneum'' sp. nov. |journal=Nordic Journal of Botany |volume=9 |issue=5 |pages=575–756|doi=10.1111/j.1756-1051.1990.tb00547.x}}</ref>
<ref name="Øvstedal & Gremmen 2001">{{cite journal |last1=Øvstedal |first1=D.O. |last2=Gremmen |first2=N.J.M. |year=2001 |title=The lichens of Marion and Prince Edward Islands |journal=South African Journal of Botany |volume=67 |issue=4 |pages=552–572|doi=10.1016/S0254-6299(15)31187-X |doi-access=free}}</ref>
<ref name="Poelt & Hafellner 1975">{{cite journal |last1=Poelt |first1=J. |first2=Hafellner |last2=J. |year=1975 |title=Schlauchpforten bei der Flechtengattung ''Thelocarpon'' |trans-title=Ascus pores in the lichen genus ''Thelocarpon'' |journal=Phyton |volume=17 |pages=67–77 |language=de |url=https://www.researchgate.net/publication/268430933}}</ref>
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<ref name="Salisbury 1953">{{cite journal |last=Salisbury |first=G. |year=1953 |title=The genus ''Thelocarpon'' in Britain |journal=North Western Naturalist |volume=1953 |pages=66–76}}</ref>
<ref name="Salisbury 1966">{{cite journal |last=Salisbury |first=G. |title=A monograph of the lichen genus ''Thelocarpon'' Nyl. |journal=The Lichenologist |volume=3 |issue=2 |year=1966 |doi=10.1017/S0024282966000197 |pages=175–196}}</ref>
<ref name="Species Fungorum synonymy">{{cite web |title=''Thelocarpon'' Nyl., Annls Sci. Nat., Bot., sér. 3 20: 318 (1853) |url=https://www.speciesfungorum.org/names/Synonymy.asp?RecordID=5430 |publisher=Species Fungorum |access-date=18 March 2026}}</ref>
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<ref name="Zahlbruckner 1902">{{cite journal |last=Zahlbruckner |first=A. |year=1902 |title=Beiträge zur Flechtenflora Niederösterreichs. VI |trans-title=Contributions to the lichen flora of Lower Austria. VI |journal=Verhandlungen der Zoologisch-Botanischen Gesellschaft in Wien |volume=52 |pages=257–270 |language=de}}</ref>
}}
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Category:Ascomycota Category:Ascomycota genera Category:Lichen genera Category:Taxa named by William Nylander (botanist) Category:Taxa described in 1852