Short-spored Subulicystidium (Trechisporales, Basidiomycota): high morphological diversity and only partly clear species boundaries Author Ordynets, Alexander https://orcid.org/0000-0002-2904-7094 Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany a.ordynets@uni-kassel.de Author Scherf, David Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany Author Pansegrau, Felix Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany Author Denecke, Jonathan Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany Author Lysenko, Ludmila Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany Author Larsson, Karl-Henrik Natural History Museum, University of Oslo, P. O. Box 1172 Blindern, 0318 Oslo, Norway Author Langer, Ewald Department of Ecology, FB 10 Mathematics and Natural Sciences, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany text MycoKeys 2018 2018-06-27 35 41 99 http://dx.doi.org/10.3897/mycokeys.35.25678 journal article http://dx.doi.org/10.3897/mycokeys.35.25678 1314-4049-35-41 FF86652FFFAF2557FFB20B15FFF6330B 1305473 Subulicystidium grandisporum Ordynets & K.H.Larss. sp. nov. Figs 6a-c ; 10i Diagnosis. Species with the largest cylindrical basidiospores ever observed in the genus (10.5-14.5 x 3.3-3.9 µm ) and relatively large cystidia with prominent regular encrustation. Type . COSTA RICA . Cartago : Faldas del volcano Irazu , 1800 m , on decayed twig, 28 May 1991 , L.Ryvarden (LR 29162 in O:F 506781) . Etymology. grandisporum (Lat.), having large basidiospores. Description. Basidiomata annual, effused, resupinate, soft and fragile, arachnoid, thin, loosely adnate. Hymenophore smooth, finely velutinous due to numerous protruding cystidia, whitish. Margin thinning out, pruinose, adnate. system monomitic. All septa with clamps. Subiculum thin, with loosely interwoven richly branched hyphae 3-4 µm wide, thin-walled, hyaline and smooth. Subhymenium thin, compact, with richly branched hyphae 3-3.5 µm wide, often covered with thin hyaline crystalline sheath. Cystidia subulate, 70-90 x 5-7 µm including encrustation, projecting up to 60 µm , without basal swelling, terminal or pleural, with thick hyaline cell wall and outer hyaline crystalline sheath covering the whole cystidium except the thin-walled, tapering apex. Crystal protrusions on cystidium are large, clearly rectangular to rounded, rather sparsely arranged in longitudinal rows. Basidia suburniform, 13-19 x 5.5-7 µm , thin-walled, with 4 sterigmata and a basal clamp, often with hyaline crystalline collar at the base. Basidiospores cylindric, adaxial side slightly concave, L=(10-)10.6-14.5(-15.3) µm , W=(3.2-)3.3-3.9(-4.2) µm , Q= (2.9-)3.0-4.0, N=48/1, with minute apiculus, smooth, thin-walled, hyaline, negative in Melzer's reagent. Remarks on species . Until now, it is the only known Subulicystidium species with such large cylindrical basidiospores. Additionally, large cystidia with regular large protrusions, together with large basidia, make the species remarkable.