Exidia spiculata Schwein.
Abstract
Exidia spiculata Schwein., Transactions of the American Mycological Society 4: 185, 1832 Fig. 23 E = Exidia glandulosa f. populi Neuhoff, Arkiv för Botanik 28 A (1): 13. Holotype. Sweden. Uppland: Uppsala, Lassby backar, Populus tremula, 10 Apr 1884, Romell 4388 (S F 207857, studied). = Exidia inflata Cazenave & G. Gruhn, Bulletin de la Société Mycologique de France 140: 214, 2024. Holotype. France. Hautes-Pyrénées: Séméac, Bois de Labarthe, Populus tremula, 26 Feb 2022, Cazenave (LIP GG-240916-001 *, isotype – H, studied). Holotype. USA. Pennsylvania: Bethlehem, Platanus sp. (cut surface of log), [no collecting date indicated], Schweinitz 1101 (PH 00062438, studied) (Fig. 23 E). Description. Basidiomata annual, at first cushion- or button-shaped, then adpressed-orbicular, up to 2 cm in diam., broadly attached, often in groups, finally fusing together and forming compound effused basidiomata but rarely reaching 4 cm in the longest dimension, up to 0.5 cm thick, gelatinous. Hymenial surface uneven or variably folded, brownish-gray to brownish-black, rarely with indistinct warts normally associated with embedded white mineral inclusions, in older basidiomata sometimes fading to yellowish-brown, in dry condition nearly black. Abhymenial surface smooth or rarely minutely dotted, concolorous with hymenial surface. Margin free, concolourous with hymenial surface, entire, even. Hyphal structure monomitic, hyphae clamped; context hyphae hyaline or grayish, thin- to slightly thick-walled, interwoven, anastomosing, occasionally encrusted, 0.5–5 μm in diam., sometimes inflated up to 7.5 μm in diam., subhymenial hyphae hyaline or grayish, thin- to slightly thick-walled, predominantly ascending, 1–4 μm in diam., basidia-bearing hyphae thin- to slightly thick-walled, 2–5 μm in diam. Hyphidia with a grayish or brownish, hyphoid or nodulose stem, 2.5–7 μm in diam., and hyaline or brownish-gray apical branches, 0.8–1.5 μm in diam., forming a continuous layer up to 60 μm thick and sometimes covered by masses of angular crystals. Probasidia tapering or clavate, 11–18 × 4–8 μm. Basidia four-celled, ellipsoid-ovoid, (9.5 –) 10–14 (– 15.5) × (7.1 –) 7.3–10.0 (– 10.2) μm (n = 50 / 4), sterigmata up to 15 × 1–2 μm. Basidiospores narrowly cylindrical to allantoid, slightly or distinctly curved, (9.8 –) 10.2–15.6 (– 15.7) × (2.8 –) 2.9–4.2 (– 4.3) μm (n = 173 / 6), L = 11.91–13.60, W = 3.44–3.77, Q = 3.41–3.74, normally aguttulate. Remarks. Exidia spiculata is one of the nigrescent Exidia spp. belonging to the E. pithya complex (Figs 10, 11). It seems that it is widely distributed in the cold temperate and boreal ecosystems of Eurasia but overlooked. Exidia spiculata inhabits dead branches or just fallen, corticated logs of many deciduous trees but with a certain preference for Salicaceae. Morphologically and phylogenetically, it is very close to the East Asian E. subglandulosa which, however, has wider basidiospores (see below). The superficially similar E. pithya has on average wider basidiospores than E. spiculata. They are more allantoid and normally aguttulate in the latter species. In E. pithya, the spores are always filled with numerous and easily detectable oil droplets (Fig. 19). Moreover, E. spiculata never produces spine-like projections on the hymenial surface, while these outgrowths are typically present in E. pithya. Exidia spiculata was first described by Schweinitz (1832) from Bethlehem, Pennsylvania. Coker (1920) studied the type material of E. spiculata and concluded that it was of no value. On the contrary, Burt (1921) found the type of E. spiculata to be identifiable. He was able to find basidiospores and associate the type specimen with a few other collections from the US North-East. Burt stressed another macroscopic feature of E. spiculata which was missing in the original description, i. e. the presence of white mineral grains on the hymenial surface, easily detectable without magnification. Both Coker and Burt were misled by Schweinitz’s remark in the protologue that E. spiculata has a papillose surface (‘ papillis frequentibus in superficie’ – Schweinitz, ibid.). They thought that this detail referred to papillae on the hymenial surface which they could not find in the type specimen. In fact, this part of Schweinitz’s description refers to the abhymenial surface which is, according to our observations, covered by small, densely arranged papillate projections, ca. 50 × 50 μm. The hymenial surface in the type collection is folded but devoid of any other kind of outgrowths. Neuhoff (1936 a) placed E. spiculata in the synonyms of E. glandulosa sensu auct. (= E. pithya in the present study). The same year, he described E. glandulosa f. populi from Sweden (Neuhoff 1936 b). In the description of this form, Neuhoff emphasized its minutely dotted abhymenial surface (‘ subtus punctato-scabra’), i. e. the same feature mentioned by Schweinitz for his E. spiculata, as well as its folded hymenial surface lacking any other projections (‘ disco plano, dein subcostato’). The type specimen of E. glandulosa f. populi perfectly matches other specimens of E. spiculata studied by us. We should note, however, that we were able to observe the papillose abhymenial surface only in a few specimens of E. spiculata (including the holotype) while it is apparently smooth in most collections studied by us. This trait is, therefore, of minor value to distinguish between E. spiculata and E. pithya. As for easily visible mineral grains, we could find them only in senescent, coalescent individuals of E. spiculata. They were both embedded and exposed. Nevertheless, if present, they give an additional clue for recognizing E. spiculata vs. E. pithya because old specimens of both species are often sterile. Basidiomata of Exidia pithya may also contain mineral concretions. However, they are small, visible only under lens, and as a rule embedded.
Authors 13
-
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
-
Komarov Botanical Institute of the Russian Academy of Sciences
Affiliation as printed
Komarov Botanical Institute, Prof. Popova str. 2, 197022 St. Petersburg, Russia
-
Affiliation as printed
Organismic Botany and Mycology, Institute of Plant Science and Microbiology, Ohnhorststraße 18, 22609 Hamburg, Germany
-
Affiliation as printed
Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, Netherlands
-
Affiliation as printed
Société Linnéenne de Lyon, 33 rue Bossuet, 69006 Lyon, France
-
Affiliation as printed
Österplana Skattegården 2, 53384 Hällekis, Sweden
-
Affiliation as printed
Globe Institute, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark
-
Affiliation as printed
Institute of Biological Sciences, University of Oslo, P. O. Box 1045, Blindern, N- 0316 Oslo, Norway
-
University of Tennessee at Knoxville
Affiliation as printed
Department of Ecology and Evolutionary Biology, University of Tennessee, 1406 Circle Drive, Knoxville, Tennessee 37996, USA
-
Affiliation as printed
Ecology and Genetics Research Unit, University of Oulu, P. O. Box 3000, FI- 90014 Oulu, Finland
-
Czech Academy of Sciences, Biology Centre
Affiliation as printed
Biology Centre, Academy of Sciences of the Czech Republic, Branišovská 31, CZ 37005, České Budějovice, Czech Republic
-
National University of Misiones
Affiliation as printed
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
-
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
Cited by 0 stored of 0
No patents citing this paper on Lens.org (checked 2026-10-11).