Exidia glandulosa Fr.
Abstract
Exidia glandulosa (Bull.) Fr., Systema Mycologicum 2: 224, 1822 Figs 19 D, 20 B, 21 ≡ Tremella glandulosa Bull., Herbier de la France 9: pl. 420, fig. 1, 1789. Lectotype (iconotype) (selected here, MBT 10031433). Fig. 1, pl. 420 in Bulliard, Herbier de la France 9, 1789. Epitype (designated here, MBT 10031434). Sweden. Västergötland: Askim, Årekärr, Alnus glutinosa, 15 Mar 1999, E. Larsson 3-99 * (GB-0150310, studied). = Exidia strigosa (P. Karst.) P. Karst., Bidrag till Kännedom av Finlands Natur och Folk 48: 451, 1889. Holotype. Finland. Varsinais-Suomi: Turku, Ruissalo, Corylus avellana, 2 Jun 1869, Karsten 2141 (H 6061342, studied). = Exidia grambergii Neuhoff, Zeitschrift für Pilzkunde 5: 187, 1926. Description. Basidiomata annual, at first button-shaped or adpressed-orbicular, up to 5 cm in diam., narrowly attached and occasionally with a reduced stalk-like base up to 2 cm long, later turbinate or nearly cupulate, up to 10 cm in diam., sometimes in large groups and partly fusing together, up to 3–4 cm thick, gelatinous. Hymenial surface uneven or variably folded, covered by rather regularly arranged spike-like black projections up to 0.25 mm long, dark gray to brownish-gray, later brownish-black, in dry condition completely black. Abhymenial surface felty or strigose, covered by densely arranged blackish hairs up to 0.2 mm long, grayish-brown to nearly black. Margin free, concolourous with hymenial surface, entire, even or lobate. Hyphal structure monomitic, hyphae clamped; context hyphae hyaline or grayish, thin- to distinctly thick-walled, predominantly interwoven, anastomosing, 1–7 μm in diam., subhymenial hyphae hyaline to grayish, thin-walled or with a distinct wall, predominantly ascending, 1–3 μm in diam., basidia-bearing hyphae 2–4 μm in diam. Hyphidia with a hyaline or grayish-brownish hyphoid stem, 2–9 μm in diam., and hyaline or grayish-brownish apical branches, 0.5–1 μm in diam., forming a continuous layer up to 100 μm thick. Probasidia clavate to broadly clavate, more rarely tapering, 12–21 × 5–10 μm. Basidia four-celled, ellipsoid-ovoid, thin- or occasionally thick-walled (wall up to 1–1.5 μm thick), (14 –) 14.5–24 (– 25) × (9.6 –) 9.7–13.7 (– 13.8) μm (n = 85 / 8), sterigmata up to 50 × 1.5–2.5 μm. Basidiospores narrowly cylindrical to cylindrical, moderately or strongly curved, (10.3 –) 11.0–17.9 (– 19.1) × (3.9 –) 4.0–6.4 (– 6.8) μm (n = 330 / 10), L = 13.53–15.87, W = 4.56–5.47, Q = 2.48–3.31. Remarks. As redefined here, E. glandulosa is morphologically and phylogenetically the closest to E. truncata. They both produce adpressed-orbicular or turbinate, nearly black basidiomata with a distinctly spinulose hymenial surface. These species also share similar ecological preferences, being collected and sometimes occurring side by side in the same habitats (nemoral or hemiboreal forests with Quercus robur), as a rule on hanging or just fallen branches. Exidia glandulosa differs from E. truncata in having a hairy abhymenial surface (scabrose or minutely punctate in E. truncata) and on average shorter basidiospores. Up to the present moment, the identity of E. glandulosa has remained controversial. Neuhoff (1936 b) made the first attempt to sort out names of the dark-colored Exidia species in Europe. He coined the name E. glandulosa (based on Buillard’s T. glandulosa) and applied it to the most common black Exidia species with prostrate basidiomata and smooth abhymenial surface. At the same time, he named a similar species with orbicular or turbinate basidiomata and uneven upper surface E. truncata. Neuhoff (ibid.) referred to descriptions of E. glandulosa and E. truncata in Systema Mycologicum (Fries 1822) and stated that they leave no doubt about Fries’ concept of these species. Moreover, he mentioned that the authentic specimens of E. glandulosa in Fries’ herbarium in Uppsala corroborate his concept. Neuhoff’s viewpoint on the identity of E. glandulosa and E. truncata was accepted by most subsequent authors (Pilát 1957; Raitviir 1970; Torkelsen 1972; Wojewoda 1981; Hansen and Knudsen 1997). In recent DNA studies, E. glandulosa and E. truncata sensu Neuhoff were adopted by Weiß and Oberwinkler (2001), Wu et al. (2020) and Ye et al. (2020). Donk (1966) proposed an alternative interpretation of the two species. He pointed to the ambiguity of Fries’ descriptions of E. glandulosa and stated that some elements of the text in Systema Mycologicum definitely refer to E. truncata. Therefore, it is highly likely that Fries himself could not distinguish between the two species. The only certain element in his introduction of E. glandulosa (Fries 1822) is a reference to Bulliard’s illustration of Tremella glandulosa (Bulliard 1789). It clearly depicts E. truncata as interpreted by Neuhoff (1936 b), and, in Donk’s opinion, also as understood by Fries himself. As a consequence, Donk (1966) synonymized E. truncata with E. glandulosa and formally introduced a new name, E. plana, for E. glandulosa sensu Neuhoff. Roberts (2009) accepted this synonymy but proposed another name, E. nigricans, for E. plana. We agree with Donk’s opinion that Fries’ concept of E. glandulosa was quite obscure and that the single clear element in his description is the link to Bulliard’s illustration of T. glandulosa. We could not trace any specimens in UPS collected or received by Fries prior to the publication of his description of E. glandulosa in 1822. Hence, it is uncertain which specimens in Fries’ herbarium in Uppsala Neuhoff referred to. However, there are two specimens with Fries’ handwritings in Lund (herbarium LD) which he studied before publishing Systema Mycologicum. One specimen labelled as Tremella arborea Huds. (LD 1473064) is identical with E. glandulosa in the sense of Donk and Roberts and the second one (‘ Tremella spiculata Pers. ’, LD 1473124) belongs to E. nigricans. Both T. arborea and T. spiculata were listed by Fries (1822) as synonyms of E. glandulosa, and this confirms Donk’s assertion that E. glandulosa sensu Fries was a mixture of (at least) two species. Exidia glandulosa has never been typified. The existence of the two authentic specimens by Fries, as well as his reference to Bulliard’s illustration of T. glandulosa, confront us with a difficult choice, because either of the specimens or the illustration can be used for typification. One option would be to select the specimen LD 1473124 as a lectotype of T. glandulosa and thus support Neuhoff’s view on the identity of this species. This would allow for the retention of E. glandulosa as it has been accepted in recent DNA studies. However, this selection would be in the explicit conflict with the original species concept presented by Bulliard (1789), as well as, to some degree, with Fries’ opinion on its identity. From his description and synonymy in Systema, we still can conclude that his E. glandulosa mainly referred to a species with a strigose abhymenial surface. We therefore support Donk’s conclusions on the identity of E. glandulosa but exclude E. truncata from its synonyms. The latter species is redescribed and discussed below. We designate Bulliard’s original illustration of T. glandulosa as its lectotype and supplement it with an epitype collected on alder (the only host tree mentioned by Bulliard in the protologue of T. glandulosa). No type material is extant for E. grambergii. The species description (Neuhoff 1926) certainly refers to E. glandulosa as redefined here. We place E. grambergii in the synonyms of E. glandulosa.
Authors 13
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University of Helsinki · Finnish Museum of Natural History
Affiliation as printed
Finnish Museum of Natural History, University of Helsinki, PO Box 7, 00014 Helsinki, Finland
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Komarov Botanical Institute of the Russian Academy of Sciences
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Komarov Botanical Institute, Prof. Popova str. 2, 197022 St. Petersburg, Russia
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Affiliation as printed
Organismic Botany and Mycology, Institute of Plant Science and Microbiology, Ohnhorststraße 18, 22609 Hamburg, Germany
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Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, Netherlands
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Société Linnéenne de Lyon, 33 rue Bossuet, 69006 Lyon, France
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Österplana Skattegården 2, 53384 Hällekis, Sweden
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Affiliation as printed
Globe Institute, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark
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Affiliation as printed
Institute of Biological Sciences, University of Oslo, P. O. Box 1045, Blindern, N- 0316 Oslo, Norway
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University of Tennessee at Knoxville
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Department of Ecology and Evolutionary Biology, University of Tennessee, 1406 Circle Drive, Knoxville, Tennessee 37996, USA
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Affiliation as printed
Ecology and Genetics Research Unit, University of Oulu, P. O. Box 3000, FI- 90014 Oulu, Finland
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Czech Academy of Sciences, Biology Centre
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Biology Centre, Academy of Sciences of the Czech Republic, Branišovská 31, CZ 37005, České Budějovice, Czech Republic
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National University of Misiones
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Instituto de Biotecnología Misiones (InBioMis), Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, Ruta Nacional N 12, km 7.5, Posadas, Misiones, CP 3304, Argentina & Instituto Misionero de Biodiversidad (IMiBio), Ruta Nacional N 12, km 5, Puerto Iguazú, Misiones, CP 3370, Argentina
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University of Helsinki · Finnish Museum of Natural History
Affiliation as printed
Finnish Museum of Natural History, University of Helsinki, PO Box 7, 00014 Helsinki, Finland
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