Pseudobaeospora pyrifera Bas & L. G. Krieglst.

Pseudobaeospora pyrifera Bas & L. G. Krieglst., Z. Mykol. 64 (2): 204 (1998) Figs 8, 9, 10 = Pseudobaeospora mutabilis Bas & Adamčík, in Adamčík and Bas, Mycotaxon 84: 272 (2002) Holotype. GERMANY • Bavaria, Lower Franconia, Kitzingen, ‘ Klosterforst’, 10 September 1995, leg. L. G. Krieglsteiner s. n. (holotype L; isotype REG). Selected iconography. Krieglsteiner (1999: 37, photo G. Wölfel); Chaillet et al. (2007: 7, photo G. Moyne); Krieglsteiner (2010: 74); Arauzo (2011 a: p. 34–36); Morozova and Popov (2013: pl. I- 2); Caillet et al. (2018: 71). Selected descriptions. Bas and Krieglsteiner (1998: 204–205); Adamčík and Bas (2002: 272–274, as P. mutabilis); Bas (2003: 175–177); Chaillet et al. (2007: 5–7); Arauzo (2011 a: 34–35); Morozova and Popov (2013: 131–132, in Russian). Description. Habit collybioid. Pileus 8–26 mm broad, conical campanulate to plano-convex, finally flattened with an obtuse umbo, margin at first slightly crenulated-undulate, not striate, flattened to revolute in mature specimens, surface dry, pruinose to minutely felted, not or only slightly hygrophanous, purplish brown (Pinkish Vinaceous, Deep Vinaceous, Plate XXVII), dark vinaceous brown to pinkish brown at centre (Dull Magenta Purple, Schoenfeld’s Purple, Indian Lake, Plate XXVI) with a paler margin (brownish pink, Pale Vinaceous, Plate XXVII). Lamellae deeply emarginate with slightly decurrent tooth to almost free, moderately crowded, L = 18–23, 1 = (1 –) 2–5, rather thick, narrow to ventricose, 2–3 mm broad, reddish violaceous to violaceous pink, becoming lilacinous ochraceous (Lilac, Plate XXV; Pale Rose-Purple, Rosolane Pink, Plate XXVI) to greyish ochraceous, with a concolorous, entire to slightly irregular edge. Stipe 25–50 × 1.2–3.0 mm, cylindrical, solid to slightly hollow at maturity, concolorous with lamellae, dark vinaceous red-brown, purplish brown, at first sparsely but entirely covered by minute silky whitish fibrils and flocks, then evidently fibrillose only at apex, with long whitish strigose felt hair at the base (Fig. 8 a, c, d). Context violaceous red, darkening when bruised. Pileus surface showing a bluish-green reaction with a drop of 5 % KOH. Smell indistinct. Taste mild. Spore-print white. Spores (Italian collections, mono-, bi- and tetrasporic) (3.5 –) 3.8–4.3 – 4.7 (– 5.8) × (2.5 –) 3.0–3.5 – 4.0 (– 5.0) μm (64 / 2 / 2), Q = (1.00 –) 1.10–1.22 – 1.35 (– 1.63), V = (13.5 –) 18.3–28.6 – 38.9 (– 73.8) μm 3, (Slovak collections, tetrasporic) (2.9 –) 3.2–3.5 – 3.8 (– 4.7) × (2.4 –) 2.9–3.1 – 3.3 (– 3.9) μm (160 / 3 / 3), Q = (0.96 –) 1.04–1.12 – 1.20 (– 1.36), V = (10.0 –) 14.2–17.8 – 21.3 (– 31.6) μm 3, globose, subglobose to subelliptical, sometimes larmiform (drop-like), colorless, smooth, with the tendency to agglomerate in tetrads or in greater numbers (clusters) (Figs 9 h, 10 j – l), contents granulose or with one or two oil-droplets (guttules), at first thin-walled and inamyloid, but maturing after liberation and becoming thick-walled (0.7–1.3 µm thick), dextrinoid, congophilous and cyanophilous; majority of spores (80–90 %) turns green-blue sea in L 4 (Fig. 9 h). Basidia 21–25 × 5.2–7.2 µm, clavate, sometimes constricted in the middle, in some collections mostly tetrasporic, but also 1–2 sporic, in others strictly tetrasporic, sterigmata up to 4 µm long. Crassobasidia (sclerobasidia) scattered, with thick dextrinoid, strongly congophilous walls (0.8–1 µm thick) turning green-blue sea in L 4 (Fig. 9 c). Hymenophoral trama subregular to irregular, slightly intertwined (intricate), consisting of hyphae up to 14 µm wide (Fig. 9 d). Cheilocystidia 15–25 × 5.8–9.7 × 2.4–5.0 µm, abundant and densely packed, mostly broadly clavate to sphaeropedunculate, sometimes lageniform, subutriform, thin-walled, colorless (Figs 9 e – f, 10 d – f). Pleurocystidia absent. Pileipellis: suprapellis consisting of loosely arranged chains of inflated pyriform to broadly clavate elements (transition between trichoderm and epithelium) up to 15 µm wide (Figs 9 a, b, 10 a – c), overlying on a subpellis made up of radially to irregularly arranged chains of largely ellipsoid to cylindrical hyphae, 7–10 µm wide, with minutely yellow-brown encrusting extracellular pigments and intracellular pigments which turn pale greenish blue in KOH (dried material). Pileitrama made up of non-dextrinoid cylindrical hyphae up to 10 µm wide. Stipitipellis consisting of 2–7 µm wide, non-dextrinoid cylindrical hyphae. Stipititrama similar to stipitipellis but hyphae up to 11 wide. Caulocystidia present (observed at stipe apex), 10–30 × 6.7–11 µm, usually clustered in tufts, thin-walled, colorless, narrowly pyriform, clavate, lageniform, sometimes irregularly shaped, often catenulated, apically rounded (Figs 9 g, 10 g – i). Clamp-connections present. Habitat and distribution. Terrestrial, single or in small groups (gregarious), rarely subfasciculate. Known from France, Germany, Italy (the present study), The Netherlands, Spain, Norway, Estonia, and Sweden (see collections in Fig. 3) and Slovakia (as P. mutabilis). Specimen examined. ITALY • 11 December 2009, Punta Ala (Castiglione della Pescaia, GR), in a mixed forest of Quercus ilex L. and Juniperus oxycedrus ssp. macrocarpa (Sm.) Neilr., leg. L. Setti (AMB 18729); 23 November 2016, Castelporziano (Ostia, RM), in a mixed forest of broad-leaved trees, leg. G. Consiglio & A. Gennari (AMB 18730). SWEDEN • Dalarna, 4 September 2018, leg. E. Larsson (GB: 0160633) (as P. pillodii). SLOVAKIA • Záhorská níñina lowland, Abrod National Nature Reserve, Závod village, among the tall vegetation of Molinia caerulea (L.) Moench, near solitary Betula and Frangula alnus Mill., 12 August 1998, leg. S. Adamčík, V. Stanová & A. Viceníková (SAV-F: 3518, holotype of P. mutabilis); • Biele Karpaty Mts., 1.5 km E of Nová Bošáca, Blažejová Nature Monument, on soil among the grass, 30 July 2005, leg. S. Adamčík (SAV-F: 3525, as P. mutabilis); • ibidem, 27 September 2005, leg. V. Kučera, (SAV-F: 3524, as P. mutabilis); • Biele Karpaty Mts., Blažejová Nature Monument, Nová Bošáca village, the settlement of Španie, 29 June 2020, leg. S. Adamčík (SAV-F: 20580, as P. mutabilis); • Biele Karpaty Mts., Krivoklátske lúky, 20 July 2020, leg. S. Adamčík (SAV-F: 20589, as P. mutabilis). Notes. Pseudobaeospora pyrifera was originally described from Southern Germany (Bavaria, Lower Franconia) and The Netherlands (Bas and Krieglsteiner 1998). Krieglsteiner (1999) reported five additional collections from the type locality (Lower Franconia) and seven collections from three other localities. At the type locality he found it sometimes to be the most abundant fungal species. It has been found in moist woods (Pruno - Fraxinetum), grasslands (Cirsio tuberosi - Molinietum) and a Juniperus stand, often together with Hygrocybe, Entoloma, Geoglossum and Ramariopsis species. The species has been later reported also from Spain, Iurreta (Bizkaia), locality of the Basque Country (N Spain), in the litter of Chamaecyparis lawsoniana (A. Murray) Parl. plantations (Arauzo 2011 a), from France (Haute-Saône and Doubs) in dry lawns (Chaillet et al. 2007; Caillet et al. 2018) and North-western Russia (Novgorod oblast, Batetsky district) in a meadow (Morozova and Popov 2013). Pseudobaeospora pyrifera was included in the CHEGD fungi (the acronym of the constituent taxa: Clavariaceae, Hygrophoraceae Lotsy, Entolomataceae, Geoglossaceae Corda and Dermoloma) by Caboň et al. (2021). CHEGD fungi are a particular group of macrofungi which is characteristic of traditionally managed and undisturbed European grasslands, and which are often the dominant soil fungi in these habitats. Pseudobaeospora mutabilis Bas & Adamčík from Slovakia was said to have many characters in common with P. pyrifera Bas & L. G. Krieglst. (Adamčík and Bas 2002; Bas 2003; Adamčík et al. 2007) but distinguished by a pileipellis structure as a transition between hymeniderm and epithelium. Moreover, its basidiomes seem to be somewhat sturdier (pileus 7–13 mm in diameter, stipe 20–30 × 1–2 mm) and the lamellae less crowded (L = 18, 1 = 1–3), KOH reaction very variable (inde nomen), on fresh material grey, on dry specimens pale green but sometimes at first violaceous. All the here sequenced collections of P. mutabilis (holotype included, SAV-F: 3518) form a highly supported clade together with those of P. pyrifera [isotype included, 10 - IX- 1995, L. Krieglsteiner (REG)] both in the ITS (Fig. 3) and multigene analyses (Fig. 2). Accordingly, P. mutabilis is here considered as a younger synonym of P. pyrifera. Bas (2003) had even inserted the two species, which we now consider synonymous, into two different groups of his intrageneric sectioning: P. mutabilis in the Celluloderma group (basidiome coloured, clamp-connections present, cheilocystidia absent or present, pileipellis hymenidermoid) together with P. celluloderma; P. pyrifera in the Pyrifera group (basidiome coloured, clamp-connections present, cheilocystidia present and conspicuous, pileipellis not hymenidermoid) together with P. jamonii and P. laguncularis. Voto (2021), in first editions of his online keys to Pseudobaeospora, included P. mutabilis in his sect. Anistoderma (pileipellis hymeniform to ephitelioid) and P. pyrifera in sect. Pseudobaeospora subsect. Pseudobaeospora (pileipellis of principally short and inflated to broad hyphae). This must make us reflect on the fact that in the past too much importance has been given to the structure of the pileipellis both as a character to delimit intrageneric taxa and to distinguish species. The discrepancies in observations of the pileipellis structure might be sometimes a result of analysis of the basidiomes in different stages of development or are due to observations from different parts of the pileus (Adamčík et al. 2007; Ronikier and Moreau 2007). Pseudobaeospora pyrifera is easily identifiable due to a unique combination of characters: violaceous pink tinges present all over the basidiome, the pa