Exidia crenata Fr.

Abstract

Exidia crenata (Schwein.) Fr., Systema Mycologicum 2: 226, 1822 Fig. 19 A ≡ Tremella crenata Schwein., Schriften der Naturforschenden Gesellschaft zu Leipzig 1: 115, 1822. Holotype. USA. North Carolina, [no collecting date indicated], Schweinitz 1141 (PH). = Tremella corrugata Schwein., Transactions of the American Mycological Society 4: 185, 1832. Holotype. USA. Pennsylvania: Bethlehem, [no collecting date indicated], Schweinitz 1113 (PH 00077946, studied). Description. Basidiomata annual, cupulate-orbicular, up to 2 cm in diam., narrowly attached, later partly fusing together but remaining separable, up to 0.5 cm thick, gelatinous. Hymenial surface uneven or folded, rarely bearing scattered granular projections up to 0.1 mm long, at first ochraceous- to reddish-brown, later dark brown, in dry condition darkening to nearly black. Abhymenial surface rough, covered by tightly arranged dots, reddish-brown or dark brown. Margin free, concolourous with hymenial surface, first entire, even or indistinctly lobate, in older basidiomata usually distinctly incised (crenate). Hyphal structure monomitic, hyphae clamped; context hyphae hyaline or yellowish, occasionally encrusted, thin- to slightly thick-walled, interwoven, anastomosing, 1–5 μm in diam., subhymenial hyphae hyaline or yellowish, occasionally encrusted, thin- to slightly thick-walled, predominantly ascending, 1.5–4 μm in diam., basidia-bearing hyphae with a distinct wall, 2–3 μm in diam. Hyphidia with a hyaline or yellowish-brownish, often encrusted, hyphoid or more rarely subfusiform stem, 2–12 μm in diam., and hyaline or yellowish apical branches, 0.8–2 μm in diam., covered by yellowish-brownish gelatinous matrix and forming a continuous layer up to 25 μm thick. Probasidia distinctly tapering or more rarely clavate, 11–15 × 5–7 μm. Basidia four-celled, ellipsoid-ovoid, (10 –) 10.5–15 (– 15.5) × (7.2 –) 7.3–10.6 (– 11.4) μm (n = 30 / 2), sterigmata up to 20 × 1.5–2 μm. Basidiospores cylindrical to allantoid, slightly or distinctly curved, (9.3 –) 10.2–14.2 (– 14.3) × (3.1 –) 3.2–4.6 (– 4.8) μm (n = 90 / 3), L = 11.30–11.73, W = 3.71–3.90, Q = 2.92–3.20. Remarks. This species was first described as Tremella crenata (Schweinitz 1822) and the same year moved to Exidia (Fries 1822). Coker (1920) studied the type material of both T. crenata and T. corrugata and placed them as synonyms of the European E. recisa (as E. gelatinosa). Since then, E. crenata was almost totally forgotten. Recently, Wu et al. (2020) reinstated E. crenata as a species on its own and provided a color photo, as well as a brief comparison of it with the newly described E. yadongensis from East Asia. We affirm their observations. Exidia crenata is phylogenetically closely related to E. yadongensis, and they belong to the E. recisa complex (Fig. 9). They can hardly be separated from each other under the microscope. Macroscopically, the scalloped (crenate) margin of mature E. crenata individuals is quite characteristic; in E. yadongensis, the margin remains more or less entire. Exidia crenata occurs exclusively in the eastern part of North America where it inhabits dead branches of Quercus spp. In turn, E. yadongensis is distributed in East Asia on various deciduous hosts.

Authors 13

1. Viacheslav Spirin

   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

2. Vera F. Malysheva

   Komarov Botanical Institute of the Russian Academy of Sciences

   Affiliation as printed

   Komarov Botanical Institute, Prof. Popova str. 2, 197022 St. Petersburg, Russia

3. Nathan Schoutteten

   Universität Hamburg

   Affiliation as printed

   Organismic Botany and Mycology, Institute of Plant Science and Microbiology, Ohnhorststraße 18, 22609 Hamburg, Germany

4. Anton Savchenko Aachen Naturalis Biodiversity Center

   Naturalis Biodiversity Center

   Affiliation as printed

   Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, Netherlands

5. Bernard Rivoire
   Affiliation as printed

   Société Linnéenne de Lyon, 33 rue Bossuet, 69006 Lyon, France

6. Jan Olsson
   Affiliation as printed

   Österplana Skattegården 2, 53384 Hällekis, Sweden

7. Thomas Læssøe

   University of Copenhagen

   Affiliation as printed

   Globe Institute, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark

8. Leif Ryvarden

   University of Oslo

   Affiliation as printed

   Institute of Biological Sciences, University of Oslo, P. O. Box 1045, Blindern, N- 0316 Oslo, Norway

9. Django Grootmyers

   University of Tennessee at Knoxville

   Affiliation as printed

   Department of Ecology and Evolutionary Biology, University of Tennessee, 1406 Circle Drive, Knoxville, Tennessee 37996, USA

10. Matti Kulju

    University of Oulu

    Affiliation as printed

    Ecology and Genetics Research Unit, University of Oulu, P. O. Box 3000, FI- 90014 Oulu, Finland

11. Josef Vlasák

    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

12. M. Victoria Vignale

    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

13. Ilya A. Viner

    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