Micropsalliota vinacea Ralaiv., Liimat. & Niskanen, in Cao et al., Fungal Diversity 132: 521 (2025)

Index Fungorum number: IF 903132; MycoBank number: MB 903132; Facesoffungi number: FoF 17107; Figs. 1, 2

Etymology – The species epithet refers to the color of the basidiomata.

Holotype – K-M 252043.

Pileus up to 2 cm in diam., at first convex, then low convex to almost plane, with a small umbo in the center, pinkish brown to vinaceous brown, dark vinaceous brown in the center, surface dry, squamulose, more densely so at the center. Lamellae free, crowded, edge even, with lamellulae, at first white, later dark brown. Stipe 4 cm long, up to 4 mm wide, white at the very top of the stipe, pale vinaceous towards the base, with a vinaceous, small, membraneous annulus and vinaceous, somewhat woolly, incomplete girdles below the annulus. Context not recorded. Odor and Taste not recorded.

Basidiospores 5.5–8 × (3–)3.5–4.5(–5) µm, amygdaloid, rarely ellipsoid, smooth, brown in KOH and Melzer’s reagent. Basidia 12.5–14.5 × 5–6.5 µm, sterigmata 1–2 µm long, clavate to cylindrical, 4-spored, rarely 2-spored, not clamped, hyaline in KOH. Cheilocystidia 28–35 × 10–13 µm, clavate to somewhat broadly utriform. Pleurocystidia 28.5–47 × 10.5–15 µm, clavate to somewhat broadly utriform. Pileipellis cutis with parallel, unclamped hyphae, up to 3–7.5 µm in diameter and with a light olive or light olive-green color.

Habitat – Dry, deciduous, tropical forest, on sandy soil among leaves.

Distribution – So far only known from Madagascar.

Material examined – MADAGASCAR, Mahajanga, Boeny Region, Ankarafantsika National Park, dominated by Euphorbiaceae-Cephalocroton, Rubiaceae, Grevia, Salacia madagascariensis, Diospyros, 13 Feb 2017, coll. S. Skarha, MAF17-084 (K-M 252043, holotype).

GenBank – K-M 252043: PQ636527 (ITS).

Notes – Micropsalliota vinacea is a second species of the genus described from Madagascar. It is not closely related to the other Malagasy species, M. squamulosa, that lacks vinaceous colors and has broader spores 6–7.5 × 4–5.5 µm. ITS sequence (GenBank PQ636527, holotype) distinct from other species of Micropsalliota. In our phylogenetic analysis groups together, but with a very low support (BS 55%), with a species from China, Micropsalliota rufosquarrosa (OM650292) and Micropsalliota cf. roseipes (OM650297) and deviating from them > 9% (64 indels and substitutions).

Figure 1 – The best scoring RAxML tree with a final likelihood value of -13,795.155676 of the genus Leucoagaricus and Micropsalliota based on the ITS region. Related sequences were retrieved from GenBank. Eighty-five specimens were included in the analysis of the ITS region which comprises 1111 characters after alignment. The tree is rooted with Cystolepiota seminuda (OM212892) and Cystolepiota seminuda (AY176350). The matrix had 722 distinct alignment patterns, with 45,12% of undetermined characters or gaps. Estimated base frequencies were: A = 0.236916, C = 0.218014, G = 0.236969, T = 0.308101; substitution rates AC = 1.217603, AG = 3.599005, AT = 1.611527, CG = 0.537104, CT = 3.659128, GT = 1.000000. Maximum Likelihood bootstrap values greater than 50% are given near to each branch. The type specimens are in bold. The new species are in blue. Names, other than those originating from the type specimens, are only indicative and not confirmed via comparison with sequences from type specimens.

Figure 2 – Micropsalliota vinacea (K-M 252043, holotype). a Basidiocystidia. b Basidiospores in KOH. c Basidiospores in Melzer’s reagent. d Basidia in Melzer’s reagent. e Pileipellis. f Cheilocystidia. g Pleurocystidia. Scale bars: a = 1 cm, b–g = 10 µm. Credit: S. Skarha (a), Anna Ralaiveloarisoa (b–g).