Pseudobaeospora celluloderma Bas

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 celluloderma Bas , Persoonia 18 (1): 119 (2002)

Fig. 12

Holotype.

ENGLAND • Surrey, Mickleham Downs , 19 June 1991, leg. A. Henrici ( K (M) 17188 ).

Selected iconography.

Karasch (2004: 34 Abb. 6).

Selected descriptions.

Bas (2003: 173–174), Adamčík et al. (2007: 370–372).

Description.

Spores (3.3 –) 3.7–4.0 – 4.4 (– 5.0) × (2.7 –) 2.9–3.2 – 3.5 (– 4.4) μm (64 / 2 / 2), Q = (1.00 –) 1.16–1.28 – 1.41 (– 1.61), V = (14.1 –) 15.9–21.5 – 27.2 (– 50.1) μm 3, globose to subglobose or broadly ellipsoid, walls up to 0.8 µm thick, dextrinoid at maturity, smooth, colorless in L 4; hilar appendix prominent, 0.8–1 µm long. Basidia 16 × 4 µm, tetrasporic, clavate, sterigmata up to 2.5 µm long. Hymenophoral trama regular to subregular, composed of globose to subglobose, broadly cylindrical, up to 22 µm wide hyphae, colorless in L 4. Cheilocystidia 23–25 × 5–7 µm, thin-walled, poorly differentiated and similar to basidioles. Pleurocystidia absent. Pileipellis: suprapellis cellulodermic / epithelioid, composed of slightly gelatinized, smooth, globose to subglobose, up to 24 × 22 µm elements; subpellis like suprapellis structure but with 21 × 13 µm elements, with rare cylindraceous hyphae; pigments greenish, intracellular. Stipitipellis consisting of up to 4 µm wide, multiseptate, closely packed, longitudinal hyphae. Stipititrama like stipitipellis structure but with up to 12 µm wide hyphae. Caulocystidia 12–22 × 2–7 µm, numerous at stipe apex, single or in small clusters, scattered towards the stipe base, often multiseptate with terminal elements cylindrical to broadly clavate. Clamp-connections rare, scattered.

Specimen examined: SLOVAKIA, Vihorlatské vrchy Mts., ca. 1.5 km SW of the church, old pastures, Strihovce village, terrestrial, on flysh, 18 April 2003, leg. V. Kučera ( SAV-F: 3516 ). SWEDEN, Medelpad, Borgsjö, öster om Östby, Örtrik granskog (Medelpad, Borgsjö, east of Östby, Örtrik spruce forest), 3 September 1991, leg. L. Andersson ( UPS-F: 623041 ) (as Pseudobaeospora pillodii ).

Notes.

Pseudobaeospora celluloderma is a well characterized species circumscribed by its minute and slender mycenoid basidiomes which are brightly purple to reddish violet when moist (reminding Laccaria amethystina Cooke ), sometimes greyish vinaceous coloured; strongly translucently striate pileus when moist; lamellae concolorous with pileus; pileus surface in KOH pale brownish to pale pinkish-greyish, clamp-connections present (sometimes as pseudoclamps, Bas 2003); cheilocystidia absent or basidiole-like, and an irregular hymenidermic pileipellis ( Bas 2002, 2003; Adamčík et al. 2007; Kalinina et al. 2020). It was reported in Europe from Austria, Denmark, England, Finland, France, Germany, Slovakia, Sweden, and Russia ( Bas 2002, 2003; Karasch 2004; Courtecuisse and Lécuru 2006; Adamčík et al. 2007; Læssøe 2008, 2012; Hausknecht et al. 2012; Kalinina et al. 2020).

The sequences from two North American collections named P. celluloderma ( KU 058501 , USA North Carolina, ECV 5550 / TENN 067659 ) and Pseudobaeospora sp. ( KU 058500 , USA, Tennessee TENN 070699 / CCB 143666 ) (Figs 2 , 3 ) are weakly supported as sisters related to the two European collections we have sequenced and studied, and probably represent one or two distinct undescribed taxa.

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 12. Pseudobaeospora celluloderma, microscopic features (UPS-F 623041). a – c Pileipellis; d cheilocystidia; e crassobasidia; f spores; a – f in ammoniacal Congo red. Scale bars: 10 µm (a, b, d); 15 µm (c); 5 µm (e, f). Photos by L. Setti.