Coniolepiota alexandri D. D. Ivanova & O. V. Morozova 2024, sp. nov.

Coniolepiota alexandri D.D. Ivanova & O.V. Morozova, sp. nov. (Fig. 3) Mycobank: MB852604. Type:— VIETNAM, Dong Nai Province, Tan Phu District, Cat Tien Map National Park, “ Lagerstroemia trail”, on termite mound, N 11.426667°, E 107.426389°, 3 June 2010, coll. O.V. Morozova, 1VN10 (holotype: LE F-349990). Etymology:—named in honor of famous Russian mycologist, Alexander Kovalenko. Diagnosis:—differs from Coniolepiota spongodes by its white overall basidiomata, bigger basidiospores, more irregular fusiform subutriform cheilocystidia, and the absence of powdery warts covering pileus. Description:— Basidiomata medium sized, white overall both when fresh and dried. Pileus 30–40 mm in diameter, white, hemispherical when young, soon expanding to wide conical, covered densely with flocculose squamules, the squamules are thicker towards the center, exceeding lamellae, the tops of some squamules have a light lilac tinge (15D3–4, 15C3). Lamellae free, crowded, slightly ventricose, remote from the stipe, 1 mm broad, white. Stipe 40–50 × 5–7 mm, cylindrical, smooth, concolorous with the pileus, powdery warts on stipe. Annulus membranous, with flocculose scales, detached to pileus when young, white. Basidiospores (6.1–)6.3–8.5 (8.9) × (3.8–)4–5 μm, Q = 1.4–1.9, Qm = 1.66± 0.1, (n = 21), ellipsoid, oblong, thickwalled, germination pore absent. Basidia (17.2–)18.8–20.8(–23.3) × (6.8–)7.9–7.7(–9) μm, clavate, hyaline, 4-spored. Cheilocystidia (24.1–)24.4–28.7(–31) × (4.4–)5–6.6 μm, irregularly fusiform with more or less distinguished necks, some are clavate, subutriform, thin-walled, hyaline. Pleurocystidia absent. Pileus covering composed of T-shaped and irregularly branching elements, individual cylindrical cells 20(40)–31(53) × 4–10 μm, with refractive connecting points at septae and ending points of the pileal elements. Habitat and distribution:—Solitary, on soil, in rain tropical forest with Tetrameles nudiflora, Lagerstroemia sp., Afzelia xylocarpa. The type specimen was found on termite mound. Known only in southern Vietnam. Additional specimens examined: VIETNAM, Dong Nai Province, Tan Phu District, Cat Tien Map National Park, Botanical Garden, rain tropical forest with Tetrameles nudiflora, Lagerstroemia sp., and Afzelia xylocarpa, on soil, 15 June 2010, coll. A. E. Kovalenko LE F-349989 (10-06-175). Notes:— Coniolepiota alexandri is characterized by the following features: medium-sized white basidiomata with flocculose squamules on pileus with tops of lilac color, overhanging the margin, powdery warts on stipe, ellipsoid spores, irregularly fusiform and subutriform cheilocystidia. This is the second species in Coniolepiota genus, and it has some features in common with the type species: convex or somewhat conical pileus, surface of which is densely covered by floccose squamules, lamellae free and remote from the stipe, oblong ellipsoid spores (Berkeley & Broome 1871, Pegler 1972), irregularly branching pileal elements and with refractive connecting points in septae (Vellinga et al. 2011, Hosen et al. 2013). However, C. alexandri forms white overall basidiomata, possesses bigger basidiospores and more irregular fusiform subutriform cheilocystidia, and lacks powdery warts covering pileus (Vellinga et al. 2011, Hosen et al. 2013). Some squamules on pileus have barely noticeable lilac parts, and this color is the same as the C. spongodes. Also, basidiomata of the new species tend to be preserved better than those of C. spongodes.