Genus of fungi
Geoglossum is a genus of fungi in the family Geoglossaceae. They are commonly called earth tongues. The type species is "Geoglossum glabrum". "Geoglossum" species are distinguished from the related genus "Trichoglossum" by the lack of setae on the spore bearing surface. "Geoglossum" species are characterized by dark, club-shaped, terrestrial ascocarps with a fertile hymenium continuing downward from the apex of the ascocarp along the stipe, eventually intergrading with a sterile stipe. The ascospores of "Geoglossum" range from translucent to dark brown, and are fusiform, and multiseptate. Identification of species is based on the gross morphology of the ascocarp, color and septation of the ascospores, and shape and ornamentation of the paraphyses.
Taxonomy.
"Geoglossum" was described by Christian Hendrik Persoon in 1794, who created the genus to accommodate "Clavaria ophioglossoides" L. and three other species: "Geoglossum hirsutum" (now "Trichoglossum hirsutum" (Pers.) Boud.), "Geoglossum lilacinum" (now "Thuemenidium atropurpureum" (Batsch) Kuntze), and "Geoglossum viride" (now "Microglossum viride" (Pers.) Gillet). Persoon expanded the genus in several subsequent publications and the name was sanctioned by Elias Magnus Fries in his 1821 "Systema Mycologicum I". Several mycologists have treated the genus extensively since Persoon's first work, including George Edward Massee, Elias Judah Durand, Curtis Gates Lloyd, Fred Jay Seaver, and Edwin Butterworth Mains.
Synonyms of "Geoglossum" include Frigyes Ákos Hazslinszky's "Cibalocoryne" and "Corynetes" (both published in 1881), Pier Andrea Saccardo's 1884 "Microglossum", and Otto Kuntze's 1891 "Thuemenidium". In 1908, Durand circumscribed "Gloeoglossum" to contain "Geoglossum" species with paraphyses in a continuous gelatinous layer on the stipe (including "G. affine", "G. difforme", and "G. glutinosum"), but the genus is not considered to have independent taxonomic significance.
Modern systematic analysis is sparse, though recent molecular studies have supported "Geoglossum" as monophyletic.
Description.
The fruit bodies of "Geoglossum" species are usually club-shaped, with a surface that is dry to sticky or gelatinous (particular in wet weather), and brown to black. The hymenium (spore-bearing surface) is confined to the upper club-shaped part of the fruit body. Stipes are slender and cylindrical, with a surface texture ranging from smooth to squamulose (covered with tiny scales), or, in some instances, covered with tufts of tiny hairs. The asci are club-shaped, inoperculate (without a cap or lid), and usually contain eight ascospores. These spores are club-shaped to somewhat cylindrical to somewhat fusiform. Brown to hyaline in color, there are both septate and non-septate forms (or, in some species, a combination of the two). There are paraphyses mixed with the asci, and in some species these occur on the stipes scattered or grouped together so as to form small tufts or scales. In some species they are spread out on the stipe surface as a continuous gelatinous layer.
Distribution.
"Geoglossum" species are found worldwide and have been studied extensively in Asia, Australasia, Europe, India, North America, and South America.
Selected species.
Index Fungorum currently lists 160 names of "Geoglossum", including forms and varieties, though many dubious, invalid names and synonyms have been published in the genus to date. The "Dictionary of the Fungi" (10th edition, 2008) recognizes 22 species. However, a number of new combinations and novel species have been proposed since, based on molecular and morphological data.
Conservation.
Several species of "Geoglossum" are considered to be of conservation significance and many species are found on Regional Red Lists of several European countries. "Geoglossum" are common components of the endangered waxcap grassland habitat in Europe. "G. arenarium" is listed as "vulnerable" in Estonia "G. atropurpureum" is a UK Biodiversity Action Plan Priority species, and is listed as "critically endangered" in Denmark and Estonia. "G. atrovirens" is listed as "critically endangered" in Estonia. "G. cookeanum" is listed as "endangered" in Switzerland. "G. difforme" is listed as "critically endangered" in Denmark and "endangered" in Sweden. "G. glabrum" is listed as "critical" in Czech Republic. "G. hakelieri" is listed as "vulnerable" in Sweden. "G. littorale" is listed as "critically endangered" in Denmark, and "endangered" in Sweden. "G. sphagnophilum" is listed as "endangered" in Denmark. "G. starbaeckii" is listed as "vulnerable" in Denmark. "G. uliginosum" is listed as "critically endangered" in Sweden. "G. umbratile" is listed as "critically endangered" in Bulgaria.
References.
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