Pseudoporpoloma pes-caprae (Fr.) Vizzini & Consiglio, in Vizzini et al., Phytotaxa 243(3): 274 (2016)
Pileus 2.0–8.5 cm broad, at first broadly conical to bell-shaped, then conico-convex to plano-convex, retaining an acute to blunt Inocybe-like prominent umbo, margin inflexed then expanded, undulate, lobed, often splitting with age; surface dry, not hygrophanous, radially fibrillose, greyish-brown to yellowish-ochre, darker at the centre and paler at the margin. Lamellae L= 45–60, l= 1–4, moderately crowded to subdistant, emarginateadnate to almost free, ventricose, intervenose, at first white, then pale grey to cream, with a concolorous, entire edge. Stipe 3–8 × 0.4–1.2 cm, cylindrical with a tapering base, solid then stuffed, longitudinally minutely fibrillose, white, sometimes yellowing towards the base, with a faint, whitish cobweb-like ring-zone in young basidiomes. Context whitish. Smell and taste farinaceous. Spore print white.
Basidiospores [64, 2, 2] (6.06) 6.64 – 7.87 (9.03) × (4.89) 4.96 – 5.79 (6.93) μm, Q = (1.17) 1.24–1.46 (1.60), Qm = 1.35± 1.113, V = (84.5) 85.6–137.3 (227.1) μm3, Vm = 111.5 ± 25.9 μm3, subglobose to ellipsoid, sometimes subcylindric, often ovoid in front view, slightly amygdaliform in side view, hyaline in L4, smooth, thin-walled, walls strongly amyloid, cyanophobic, usually with a large central oil drop, hilar appendix rather long and prominent, 0.8–1.0 μm long. Basidia 28–32 × 7.5–9 μm, clavate, usually tetraspored (rare bisporic basidia observed), sterigmata up to 5 μm long. Hymenophoral trama regular to subregular, made up of hyphae up to 14 μm wide, hyaline even in L4. Cheilocystidia 20–30 × 7–8.5 μm, rare, often basidia-like, thin-walled, versiform, flexuous, lobed. Pleurocystidia not observed. Pileipellis suprapellis a cutis of subparallel, variously interwoven hyphae, 3–6 μm wide, cylindrical, with smooth, undifferentiated to slightly enlarged, claviform terminal elements, up to 10 μm wide; pigment intracellular, light brown; subpellis consisting of hyphae which gradually increase their volume towards the trama, up to 10(20) μm wide, subisodiametric to largely elliptic (pseudoparenchymatic subpellis); trama hyphae cylindrical, up to 20 μm wide. Clamp-connections present throughout. Thromboplerous hyphae present in the trama. Hyphal system monomitic.
Ecology & distribution: terrestrial, gregarious, usually in dry and unfertilized, nutrient-poor grasslands, probably saprotrophic, fruiting in late summer to autumn. It is very rare but widespread in Europe. The species is included as endangered in red list of countries like Germany, Austria, Switzerland, Poland and Sweden.
Index Fungorum number: IF815367
Figure 1. Phylogeny of selected members of the Tricholomatoid clade based on a Bayesian and Maximum Likelihood Inference analysis of a supermatrix of three nuclear gene regions (nrITS, nrLSU, rpb2). Bayesian posterior probability (BPP) values (in bold) ≥ 0.75 and Maximum Likelihood bootstrap (MLB) values ≥50% are shown on the branches. For each taxon voucher number and Genbank accession numbers are given. The newly sequenced collections are in bold.
Figure 2. Pseudoporpoloma pes-caprae, macro- and micromorphological features. a, b Basidiomata (collections CF-PORP27080802 and TO-AV20915). c Pileipellis (in ammoniacal Congo red). d Spores (in Cotton blue) e Spores (in Melzer’s reagent). f Elements of the lamella edge (in ammoniacal Congo red). c–f from CF-PORP27080802 (photos by L. Setti); a photo by N. Oppicelli; b photo by C. Frund. Scale bars a, b = 2 cm.