Pseudobaeospora pyrifera Bas & L. G. Krieglst.

Vizzini, Alfredo, Consiglio, Giovanni, Adamčíková, Katarína, Setti, Ledo & Adamčík, Slavomír, 2025, Pseudobaeosporoideae, a new subfamily within the Tricholomataceae for the genus Pseudobaeospora (Agaricales, Tricholomatineae) based on morphological and molecular inference, IMA Fungus 16, pp. e 144994-e 144994 : e144994-

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 pale green to greenish blue reaction of pileus surface in KOH, mainly clavate cheilocystidia, pileipellis consisting of repent chains of inflated elements, and very small subglobose spores ( Bas and Krieglsteiner 1998; Bas 2003; Arauzo 2011 a). It contains peculiar metabolites named pyriferines A – C, which have an unusual eight-membered N / O-acetal ring, derived from L-glutamic acid ( Quang et al. 2008). Adamčík et al. (2007) noted in some habitats the occurrence of collections with reddish brown basidiomes (see also our Fig. 8 a , collection AMB 18729 ), instead of purplish violaceous ones, and they demonstrated that the colour of basidiomes was not affected by soil pH. Colour change to bluish grey on surfaces of basidiomes reported in original description of P. mutabilis ( Adamčík and Bas 2002) was later not confirmed as a consistent character and might be due to local context pigment degradation rather than oxidation ( Adamčík et al. 2007).

Macro- and micromorphology of the Italian collections are fully consistent with the original description ( Bas and Krieglsteiner 1998; Bas 2003) and French ( Chaillet et al. 2007), Spanish ( Arauzo 2011 a) and Russian ( Morozova and Popov 2013) collections, excepted for the spores that are slightly longer [3.8–4.7 × 3.0–4.0 µm (on average 4.3 × 3.5 µm) vs 2.8–3.7 (– 4.2) × 2.6–3.5 (– 3.8) µm, vs 3.5–4.0 × 4.0–4.5 µm, vs 3.1–4 × (2.8 –) 3.1–3.6 μm (on average 3.58 × 3.25 µm), and vs 2.9–3.7 × 2.6–3.2 µm, respectively] and subglobose to broadly ellipsoid instead of globose to subglobose (Qm = 1.22 vs 1.05–1.10, and 1.1, respectively). These sporal size discrepancies can be explained by the possible different percentage of (mono-) bisporic basidia on tetrasporic ones between the different collections. In fact, we report below the spore measurements summing the Slovak collections (“ P. mutabilis ”, which are exclusively tetrasporic) and Italian collections (which are mono-bi-tetrasporic): P. pyrifera + P. mutabilis – spores (2.9 –) 3.2–3.7 – 4.2 (– 5.5) × (2.4 –) 2.9–3.2 – 3.6 (– 4.7) μm (224 / 5 / 5), Q = (0.96 –) 1.05–1.15 – 1.26 (– 1.63), V = (10.0 –) 12.9–20.9 – 28.8 (– 65.2) μm 3.

In this way the spore values are very close to those reported in the literature. It is also worth to mention, that part of the discrepancies in published microscopic descriptions are due to an underestimation of the importance of the number of spores produced on the basidia.

In Europe P. jamonii Bas, Lalli & Lonati from Italy (Piedmont, Monte Rosa 1300 m, and Abruzzo) ( Jamoni and Bon 1996; Bas et al. 2002; Bas 2003) seems to be the macromorphologically closest relative of the present species. It differs, however, by the more elongate clavate to (sub) lageniform, cylindrical or irregularly shaped cheilocystidia (15–43 × 4–10 μm), the presence of a distinct suprapellis of comparatively narrow hyphae, slightly larger and slightly more ellipsoid spores (3.2–4.0 × 2.8–3.5 μm, average Q = 1.10–1.15), and a different KOH reaction of the context of the stipe (green).

Pseudobaeospora basii Adamčík & Ripková from Slovakia has a very similar microscopic structure but its basidiomes lack any purple or lilac tinges ( Adamčík and Ripková 2004 a). Unfortunately, attempts to sequence its holotype collection ( SAV-F: 3506 ) did not lead to obtaining a good ITS sequence to compare to.

Pseudobaeospora dichroa Bas (reported from England and Spain) has a pileus surface turning reddish purplish in KOH; pileipellis of often erect, catenulate hyphae near the centre, sometimes with a thin suprapellis, and towards margin of broad repent hyphae. L = 16–30, l = 3–5; pileus and lamellae with shades of red when dried; spores 3.0–4.0 (– 4.3) × 2.7–3.5 µm, average Q 1.10–1.20 (1.25); cheilocystidia 10–45 × 3.5–10 (– 17) µm, (often irregularly) clavate to lageniform, sometimes filiform, abundant to sparse or absent, sometimes with violaceous content ( Bas 2003; Arauzo 2011 a).

Pseudobaeospora laguncularis Bas (reported from England, France, Germany, Spain) is very well characterized by the abundant, very slender cheilocystidia, at present unique in the genus. So far it is also the only species with small, scattered, refractive bodies turning red or red brown in KOH on caulocystidia and cheilocystidia, and sometimes also on the pileipellis, and with distinct, albeit sometimes sparse pileocystidia ( Bas 2003; Arauzo 2011 a; Clesse 2012). Pseudobaeospora laguncularis var. denudata Bas differs from the type by lacking the suprapellis of narrow hyphae. The collection of P. laguncularis var. denudata here sequenced, coming from the same locality of the type (topotype) [LIP PAM 99101004, France, Savoie, Billième, forêt de Lierre, sous Buxus sempervirens L. et Quercus pubescens Willd. sur calcaire, alt. 400 m 10 octobre 1999, leg. Maurice Durand & Pierre-Arthur Moreau, 45.708663, 5.810281, Fig. 4 c ] is molecularly distinct from all the other sequenced species (Figs 2 , 3 ).

Among the non-European species, P. chilensis E. Horak from Chile differs by tiny, very slender basidiomes, inconspicuous, narrow cheilocystidia, and narrower pileipellis elements ( Horak 1964).

Pseudobaeospora wipapatiae from Hawaii, differs in forming deep ruby-colored basidiomes, with a pileus rugulo-striatulate nearly to disk, two-spored basidia, irregularly cylindrical to clavate or irregular in outline, sometimes mucronate, amyloid cheilocystidia, an irregular hymeniderm pileipellis with abundant erect pileocystidia and tissues that initially turn deep ruby then change to lilac grey in 3 % KOH ( Desjardin et al. 2014).

Agaricus fuscolilacinus Peck from Adirondack Mts. of New York ( USA), based on the analysis on type material made by Desjardin (2004), who considers the species to belong to Pseudobaeospora , is distinguished by brownish lamellae, ellipsoid to lacrymoid bigger spores, 4.2–6.8 × 3.2–4.0 µm (on average 5.2 ± 0.6 × 3.5 ± 0.2), Q = 1.2–2.0 (Qm = 1.5 ± 0.2), two-spored basidia, and lack of cheilocystidia.

Figures

Figure 2. Mid-point rooted Bayesian phylogeny (nrITS, nrLSU, nrSSU, RPB 2 - exons) of the Tricholomataceae s. s. Nodes were annotated with Bayesian PP (left) and ML BP (right) values, with the significance threshold considered as Bayesian PP ≥ 0.95 and / or ML BP ≥ 70 %. Subsignificant support values were annotated in parentheses. Boldface names represent samples sequenced for this study.

Figure 3. Bayesian inference phylogram built with ITS nucleotide sequence of Pseudobaeospora, rooted with Tricholoma inamoenum (Tricholomataceae) as outgroup. Nodes were annotated with Bayesian PP (left) and ML BP (right) values, with the significance threshold considered as Bayesian PP ≥ 0.95 and / or ML BP ≥ 70 %. Subsignificant support values were annotated in parentheses. Boldface names represent samples sequenced for this study. Clades are named following Craig et al. (2023).

Figure 4. Basidiomes of some sequenced Pseudobaeospora collections. a P. calcarea (LIP PAM 06090111 - FR 2013078); b P. cyanea (GDOR M 3986); c P. laguncularis var. denudata (LIP PAM 99101004 - FR 2013079); d P. pillodii (KRAM F- 53314); e P. terrayi (SAV-F: 3317, holotype); f P. terrayi (SAV-F: 20813). Lectotype of. C. pillodii; g Quélet’s original plate, pl. XV, fig. 4. Photos: a, c by P. A. Moreau; b by D. Gisotti; d by A. Ronikier; e, f by S. Jančovičová.

Figure 8. Pseudobaeospora pyrifera. Basidiomes. a AMB 18729; b AMB 18730; c SAV-F: 3518 (holotype of P. mutabilis); d – f SAV-F: 3524. Photos: a, b by G. Consiglio; c – f by S. Jančovičová.

Figure 9. Pseudobaeospora pyrifera, microscopic features (AMB 18730). a, b Pileipellis; c crassobasidia; d hymenophoral trama; e, f cheilocystidia; g caulocystidia; h spores; a, b, e, g in ammoniacal Congo red; c, d, f, h in L 4. Scale bars: 20 µm (a, d); 5 µm (b, c, e – h). Photos by L. Setti.

Figure 10. Pseudobaeospora pyrifera, microscopic features (collections named as P. mutabilis). Pileipellis. a SAV-F: 20580; b SAV-F: 20589; c SAV-F: 3524. Cheilocystidia; d SAV-F: 20580; e SAV-F: 20589; f SAV-F: 3524. Caulocystidia; g SAV-F: 20580; h SAV-F: 20589; i SAV-F: 3524. Spores; j SAV-F: 20580; k SAV-F: 20589. l SAV-F: 3524; a – l in ammoniacal Congo red. Scale bars: 10 µm (a – f, h – i); 20 µm (g). j – l. Photos by L. Setti.