Pseudobaeospora calcarea

Pseudobaeospora calcarea / P. terrayi complex Figs 4 a, e, f Notes. Pseudobaeospora calcarea was described from Switzerland occurring among and on mosses [mainly Hypnum cupressiforme Hedw., Dicranum scoparium Hedw., Hylocomium splendens (Hedw.) W. P. Schimp., and Pleurozium schreberi (Brid.) Mitt.] in coniferous woods (Pinus sylvestris with Quercus pubescens). It was placed into the informal Albidula group as circumscribed by Bas (2003), encompassing species with white to pale buff basidiomes, clamp-connections, absent cheilocystidia and pileipellis without inflated elements. This species differs from all others of this group by a very acrid taste, a negative reaction with KOH (no yellow discoloration) and the absence of clamp-connections in most of the trama and pileipellis hyphae (Clémençon and Ayer 2007). Adamčík and Jančovičová (2011) described P. terrayi, a minute, not moss-associated species from Slovakia, which was included in the Albidula group due to the white basidiome colour, despite the presence of cheilocystidia. The species was distinguished from P. calcarea by very small basidiomes (pileus 5–8 mm wide versus 7–20 mm), more distant lamellae (L = 11–18 versus 16–28), a mild taste, an occasional presence of an unpleasant fishy smell, a yellowish-greenish discoloration in 5 % KOH, presence of cheilocystidia, which are somewhat basidia-like, but often broader and sometimes with distinctly thickened walls and / or incrusted surface, and clamp-connections present in all tissues. In our ITS analysis (Fig. 3) three collections of P. calcarea, including a specimen from Switzerland (LIP PAM 06090111), and two collections of P. terrayi (holotype included, SAV-F: 3317) were found intermixed with each other in a strongly supported clade (PP 1.0, ML BP 92 %), suggesting a possible conspecificity of P. calcarea and P. terrayi. Unfortunately, the holotype and isotype collections of P. calcarea (kept at LAU) have not been declared available for molecular analysis (Patrice Descombes, personal comm.). Multigene analysis is essential also to confirm that variability within this clade in the ITS region does not correspond to more than one species as documented in P. pillodii and P. deceptiva complex. Specimen sequenced. P. calcarea: SUISSE, Grisons, Alvaneu-Bad, ripisylve à Alnus incana, 1 September 2006, leg. Pierre-Arthur Moreau. 46.66591, 9.64329, (LIP PAM 06090111). P. terrayi: SLOVAKIA, Laborecká vrchovina Mts., ca. 1 km NE of Svetlice village, the riverside meadow extensively used as pasture, on ground among ca. 15–30 cm tall herbal vegetation composed of Achillea millefolium L., Agrimonia eupatoria L., Agrostis capillaris L., Dactylis glomerata L., Daucus carota L., Festuca pratensis Huds., F. rubra L., Jacea pratensis Lam., Leontodon hispidus L., Lotus corniculatus L., Pimpinella saxifraga L., Plantago lanceolata L., Poa pratensis L., Thymus pulegioides L., Tithymalus cyparissias L., Trifolium repens L., Veronica chamaedris L. and Viola hirta L., 458 m, coord. 49°11'12.9"N, 22°02'55.8"E, 23 Oct 2007, leg. J. Terray (SAV-F: 3317 holotype); Kremnické vrchy Mts., Tajov, pasture W of the village centre, 24 October 2020, leg. S. Adamčík (SAV-F: 20813).