Pseudolagarobasidium pallens Motato-Vázq. & Westphalen, 2022

Westphalen, Mauro C. & Motato-Vásquez, Viviana, 2022, A new species of Pseudolagarobasidium from Brazil and new insights on Cerrena (Basidiomycota, Cerrenaceae), Phytotaxa 555 (2), pp. 159-168 : 163-165

Pseudolagarobasidium pallens Motato-Vázq. & Westphalen spec. nov. Figs. 2–3

MycoBank: MB 840534

Pseudolagarobasidium pallens can be recognized within the genus by the combination of pale cream to buff subceraceous basidiomes, the hymenophore composed of flattened and clustered teeth and the large basidiospores (4.6–)4.9–6.4(–6.8) × 3.2–4.5 µm.

Type.— BRAZIL. Rio Grande do Sul: Caxias do Sul, Comunidade de Nossa Senhora de Lourdes, 3 Légua , aprox. 800m altitude, 06 April 2017, M.C. Westphalen 534/17 (holotype SP!) .

Etymology.— pallens (Lat.) refers to the pale color of the basidiomes when fresh.

Basidiomes resupinate, adnate, cream when fresh becoming straw colored to pale brown upon drying, usually growing on branches and forming patches with up to 8 × 3.5 cm. Margins very thin to absent, entire, up to 1 mm wide. Hymenophore hydnoid, teeth often laterally flattened, 2–4 per mm, solitary or fused at the bases, with acute apices, generally 2–4(–5) mm long. Context very thin, homogeneous, white to cream, somewhat fibrous, up to 0.5 mm thick.

Hyphal system monomitic. Generative hyphae clamped, thin to slightly thick walled, CB+; tramal hyphae 2.5–5 µm wide, straight to dichotomously branched, subicular hyphae similar, but more often branched and tortuous. Cystidia of two types present. Tramal cystidia numerous, thin-walled, hyaline, smooth, fusiform, clavate or oboclavate, obtuse at the apex, embedded in the trama or protruding in the hymenium, strongly colored in cotton blue, 6–10 µm wide, widened part up to 35 µm long, CB+. Hymenial cystidia similar to tramal cystidia in shape, but usually slightly smaller and arising from the subhymenium and hymenium, 4–9 µm wide and up to 20 µm long. Basidia clavate, tetrasporate, 12–18 × 4–6 μm. Basidiospores hyaline, smooth, broadly ellipsoid, CB+, IKI-, (4.5–)4.8–6.1(–6.4) × (3.2–)3.4–4.1(– 4.3) μm, Lm × Wm = 5.4 × 3.7 μm, Q = 1.4–1.6, Qm = 1.5 (n = 110/4).

Ecology and Distribution.— Found growing on dead wood of unidentified angiosperms. Known from southern and southeastern Brazil.

Comments.— Pseudolagarobasidium pallens is characterized by the subceraceous, cream to pale buff basidiomes with hydnoid hymenophore, usually presenting laterally flattened teeth fused at the bases. Macroscopically, P. pronum and P. conspicuum are similar due to the pale colored basidiomes, but they differ by the more chalky and brittle consistency. In addition, P. pronum has and smaller basidiospores, 4.0–5.5 × 3–3.7(−4.3) μm, and it is distributed in Asia and Australia, while P. conspicuum is distributed in the European continent. ( Nakasone & Lindner 2012, Nakasone 2015). Pseudolagarobasidium venustum was also described from Brazil, but is easily distinguished by the pale yellow to orange basidiomes, teeth studded with knobs or warts and smaller basidiospores 4–5 × 3.2–3.7 µm ( Nakasone & Lindner 2012).

Phylogenetically, P. pallens forms a sister clade with P. belizense ( Fig. 1 ). However, P. belizense can be easily distinguished morphologically by the odontioid to warty grayish basidiomes ( Fig. 2 ), more densely arranged hyphae in the trama of the teeth and subiculum, and slightly smaller basidiospores 4.2–5.0(–5.2) × 3–3.5(–3.7) µm ( Fig. 3 ).

Additional specimens examined. — BRAZIL. Rio Grande do Sul: Riozinho, Parque do Conduto , 24 June 2017, M.C. Westphalen 570/17 (paratype, SP). São Paulo: São Paulo, P.E. Fontes do Ipiranga, 17 March 2017, RP387 (paratype, SP); Mogi-Guaçu, Parque Florestal São Marcelo , 16 June 2016, AL147 (paratype, SP). P. belizense — BELIZE. Cayo District, south of Doyle’s Delight Peak , 11 August 2004, D. Lindner DLC 04–31 ( BPI, holotype) .

Figures

FIGURE 1. Phylogenetic relationships in Cerrenaceae clade inferred from a combined dataset of ITS and nLSU sequences, conducted by Bayesian inference.All sequences generated in this study are indicated in bold faces. Numbers at branches indicate Bayesian posterior probability values / bootstrap frequency. Two letter codes after voucher specimens denote country of origin (ISO 3166 - Alpha 2). The bar indicates the number of expected substitutions per position.

FIGURE 2. Dried basidiomes. A – B. Pseudolagarobasidium belizense (DLC 04–31, holotype); C. P. pallens (534/17 holotype). Scale bars:A = 1 cm, B–C = 5 mm Photos: Mariana Drewinski (A and B) and Mauro Westphalen (C).

FIGURE 3. Pseudolagarobasidium pallens (A–B) and P. belizense (C). A. Section of the basidiome showing the hymenium and trama. B. Basidiospores. C. Basidiospores (from holotype). Scale bars: A = 10 µm, B–C = 5 µm. Drawings by Viviana Motato-Vásquez.