Pseudosperma franchettii G.B. Galeotti, A. Rubini, R. Para, C. Riccioni, B. Belfiori, 2025

Galeotti, Giovanni B., Rubini, Andrea, Para, Roberto, Riccioni, Claudia & Belfiori, Beatrice, 2025, Description of two new species of Pseudosperma in central Italy, Phytotaxa 693 (2), pp. 113-132 : 124-127

Pseudosperma franchettii G.B. Galeotti, A. Rubini, R. Para, C. Riccioni, B. Belfiori sp. nov. ( Figs. 5–7 ).

MycoBank no. MB856530

Holotype:—Italy. Umbria ( Central Italy ), Villa Montesca City Park, GPS coordinates: 43°27’03.5” N 12°13’29.1” E, elev. 400 m, gregarious, under broadleaf and conifer trees. 27 June 2023, Galeotti G.B. (holotype PERU! m-4473, isotype GDOR! 5769). GenBank: PQ563302 ( ITS), PQ563296 ( LSU), PQ561213 (rpb2).

Etymology:—This species is named in honor of Baron Leopoldo Franchetti, a Senator of the Kingdom of Italy in the early 20 th century and the founder of the Villa Montesca Park, where the specimens were discovered.

Diagnosis:— Pseudosperma franchettii is characterized by its slender and robust appearance, a stipe that is nonbulbous and deeply rooting, a pileus of straw-yellow colour with a rusty red centre, and presence of a velipellis that is abundant only in young specimens but tending to dissolve at maturity. Microscopically it is characterized for the presence of polymorphic cheilocystidia: predominantly clavate but also cylindrical, asymmetric and fusiform. Additionally, the ITS sequence differs by more than 3 % from those of closely related species such as P. minutulum and P. pinophylum .

Description:— Pileus 30–70 mm large, moderately fleshy, conical-campanulate, later flattening with a prominent and acute umbo. Pileus margin exceeding lamellae and heavily lacerated, slightly involute even at maturity. Cuticle dry, rimose, fibrillose, often becoming dissociated at maturity. Young specimens are covered by a whitish velipellis, which quickly disappears as the basidiomata develop. In mature specimens, the pileus exhibits a straw-yellow background with a compact rusty-red disk with longitudinal, innate, fibrils of the same colour, extending to the margin. Hymenophore with lamellae moderately dense, adnate, sinuous, and slightly ventricose. Initially yellowish with olive shades, becoming ochre-brown at maturity, with a whitish lamellar edge. Lamellulae of various sizes are present. Spore print rusty-brown. Stipe 50–120 × 10–15 mm, robust and elongated, cylindrical, sometimes sinuous and curved. The base is slightly broadened or sub-clavate, deeply rooted. The surface is fibrillose and pruinose, particularly near the apex. Context fibrous, especially in the stipe, w hite, with slight ochre tones in some areas, slightly browning upon air exposure. Odour sweet, honey-like, faint spermatic in young specimens, nearly absent in mature ones.

Basidiospores (8.7) 9.5–11.3 (13.1) × (5.5) 6.0–7.1 (7.8) µm, L × W = 10.3 × 6.6 µm, Q = (1.3) 1.4–1.7 (1.9), Qm = 1.6, (n = 76), smooth and asymmetric, ellipsoid, amygdaliform, ovoid, mono- and biguttulate, with marked heterospory observed in different specimens from the same collection. Basidia (27.5) 29.8–39.5 (45.5) × (10.2) 10.4– 12.7 (14.3) µm, L × W = 34.5 × 11.5 µm, (n = 24), clavate, pluriguttulate, predominantly tetrasporic, sometime bisporic. Cheilocystidia (32.1) 35.9–49.8 (59.1) × (8.1) 9.5–13.8 (17.8) µm, L × W = 42.2 × 11.5 µm, (n = 32), predominantly clavate, cylindrical, asymmetric, rarely fusiform. Pleurocystidia a bsent. Pileipellis (53.5) 76.3–126.4 (135.2) × (4.2) 4.6–6.6 (7.0) µm, L × W = 101.6 × 5.5 µm, (n = 22) consisting of parallel hyphae (a cutis structure). Subpellis (70.3) 92.1–243.4 (263.2) × (7.8) 8.2–12.8 (16.9) µm, L × W = 163.7 × 10.8 µm, (n = 22), composed of thicker hyphae in the internal layers, coated with ochre pigment and finely encrusted. Stipitipellis (53.8) 57.2–107.3 (131.1) × (4.5) 5.1–7.4 (8.2) µm, composed of parallel cylindrical hyphae. Caulocystidia (21.4) 31.8–76.7 (80.1) × (7.0) 8.0–10.6 (12.7) µm, L × W = 53.6 × 9.2 µm, (n = 26), present only at the stipe apex, highly variable in shape, cylindrical, subcapitate, sometimes lanceolate, catenulate, and diverticulate. Clamp connections numerous, present in all tissues.

Additional specimen examined: —Italy. Umbria (Central Italy), Villa Montesca City Park, GPS coordinates: 43°27’03.5” N 12°13’29.1” E, elev. 400 m, gregarious, under broadleaf and conifer trees, 16 May 2024, Galeotti G.B. ( PERU! m-4474).

Figures

FIGURE 5. P. franchetti, morphology of basidiomata (A–B) (Holotype, PERU m-4473), (C) (PERU m-4474). Photos: G.B. Galeotti. All bars = 1 cm.

FIGURE 6. P. franchettii (Holotype, PERU m-4473), micro morphological characters: (A) basidia, (B) basidiospores, (C) cheilocistidia, (D–E) caulocystidia. Photos: G.B. Galeotti.All bars = 10 μm.

FIGURE 7. P. franchettii (holotype PERU m-4473), line drawing of microscopic structure: (A) Basidia, (B) cheilocystidia, (C) caulocystidia, (D) basidiospores.All bars = 10 μm.