Descidia repanda Spirin 2026, comb. nov.

Abstract

Descidia repanda (Fr.) Spirin comb. nov. Figs 15 H, 16 B ≡ Exidia repanda Fr., Systema Mycologicum 2: 225, 1822. Neotype (selected by Aoki and Tubaki 1986: 881). Sweden. Uppland: Lena, Ängeby, Rönningen, Betula sp., 11 Nov 1935, Bruun & Lundell (Lundell & Nannfeldt, Fungi Exsiccati Suecici # 266) (UPS F-010989, studied). = Exidia qinghaiensis S. R. Wang & Thorn, Mycoscience 62: 213, 2021. Holotype. China. Qinghai: Menyuan, Xianmi, Betula sp., 19 Oct 2004, Xiaoqing (HMAS 156328 *). Description. Basidiomata annual, first cushion-shaped, adpressed-orbicular or turbinate, up to 3 cm in diam., narrowly or broadly attached, later fusing together and forming compound cerebriform basidiomata, up to 20 cm in the longest dimension and 2 cm thick, gelatinous. Hymenial surface smooth to indistinctly or clearly folded, amber-yellow to reddish or reddish-brown, in dry condition normally darkening to dirty-brown, sometimes with a lilac hue. Abhymenial surface smooth, concolourous with hymenial surface. Margin free, concolourous with hymenial surface. Hyphal structure monomitic, hyphae clamped; context hyphae hyaline, thin- to slightly thick-walled, interwoven or subparallel, spaced, anastomosing, 0.5–6.5 μm in diam., subhymenial hyphae hyaline or yellowish, thin- to slightly thick-walled, predominantly interwoven, 1–4 μm in diam., basidia-bearing hyphae 2–4 μm in diam. Hyphidia with a hyaline or yellowish, often slightly thick-walled, hyphoid stem, 2–5 μm in diam., and hyaline apical branches, 0.5–1.2 μm in diam., in mature basidiomata cemented by yellowish or reddish amorphous substance and forming a continuous layer up to 35 μm thick. Probasidia predominantly tapering, 9–20 × 4–6 μm. Basidia four-celled, ellipsoid-ovoid, (9 –) 9.5–16 (– 16.5) × (7.6 –) 7.8–9.7 (– 10.3) μm (n = 40 / 4), sterigmata up to 15 × 1.5–2 μm. Basidiospores narrowly cylindrical to allantoid, usually distinctly curved, (9.2 –) 10.1–15.1 (– 15.4) × (2.7 –) 2.8–4.1 (– 4.2) μm (n = 150 / 5), L = 11.87–13.11, W = 3.15–3.75, Q = 3.19–4.19. Remarks. Descidia repanda is widely distributed in the temperate and boreal areas of Eurasia. It occurs exclusively on dead, hanging or just fallen, corticated branches of Betula spp. No verified records of D. repanda from North America are known to us. Macroscopically, D. repanda is most similar to Exidia candida. Their differences are discussed under the latter species. This species was first introduced by Fries (1822) as Exidia repanda. No original specimens of E. repanda exist and the protologue implies that Fries’ species was originally a mixture of E. repanda in the present sense and E. candida. In particular, Alnus as a host tree and minute, papillose projections on the hymenial surface point to the latter species. Nevertheless, E. repanda was neotypified with a specimen growing on Betula (Aoki and Tubaki 1986). We studied the neotype and concluded that it is conspecific with E. repanda as it was interpreted in North Europe by Neuhoff (1935), Raitviir (1970), Torkelsen (1972), and Hansen and Knudsen (1997). Specimens and sequences of E. repanda by Wu et al. (2020) belong to Exidia straminea instead (see below).

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