Amanita amplivelata Hanss, Assyov, Bozok, TaŞkın & Borovička, 2024

Hanss, Jean-Michel, Bozok, Fuat, Assyov, Boris, Yarar, Mahmut, Borovička, Jan, Ševčíková, Hana, Corriol, Gilles, Moreau, Pierre-Arthur & Taşkin, Hatira, 2024, Amanita amplivelata, (Amanitaceae, Agaricales), a remarkable new Eurasian species of the section Vaginatae, Phytotaxa 660 (1), pp. 1-21 : 6-8

Amanita amplivelata Hanss, Assyov, Bozok, TaŞkın & Borovička , sp. nov. ( Figs. 3 , 4 )

MycoBank 849891

Etymology:—amplus (Latin)—ample, and velum (Latin)—veil, refers to the well-developed, thick universal veil, which is characteristic for the new species.

Diagnosis:— Amanita amplivelata differs from A. crocea by different colours, variable from one collection to another, viz., silvery grey, mouse grey, greyish ochraceous, buff, olivaceous, rarely whitish; by the white universal veil sometimes stained yellow ochraceous or ochraceous grey on the velar remnants of the pileus and the saccate volva; by the white floccose stipe covering, by the predominantly broadly ellipsoid basidiospores, as well as by its inferred mycorrhizal relationship with trees of Salicaceae , the genus Populus in particular.

Type: — BULGARIA. Pernik province, between Trun town and Ezdimirtsi village, 42°50’07.6”N, 22°41’28.2”E, elev. ca 805 m, forest of Populus tremula and Carpinus betulus , 5 September 2020, B. Assyov (SOMF 30801!, holotype; LIP 0004524!, FBozok 1226!, isotypes; nrITS: OR524133; nrLSU: OR512418; TEF-1α: OR526520).

Description:— Pileus up to 15 cm diam, at first campanulate or sometimes hemispherical, then expanding to convex, convex-applanate, in old basidiomata completely applanate or sometimes slightly depressed in the center, sometimes slightly umbonate, dry to viscid, especially in wet weather, in young basidiomata very finely rugulose, later usually more or less smooth, sometimes with an innately fibrillose pattern, pale grey (1B1, 4B1), ash grey (1B2), platinum (1–3D1), pearl grey (3B1), smoke grey (3C2), greyish beige (4C2), olive (3D3–4), ivory (4B3), brownish grey to greyish brown (7–8D2–3), usually darker in the center, somewhat paler towards margin and becoming darker again in the area of the marginal striations, occasionally entirely off-white, in some collections with iridescent or metallic shine; pileal margin striate, striations deep 1/4 to 1/3, sometimes up to 1/2 of pileal radius; velar remnants often (in over 50 % of basidiomata) present on pileal surface in the form of single, adpressed, irregularly shaped patches or sometimes as numerous fragments, initially whitish, quickly becoming ochraceous. Stipe up to 17 cm long, 1.5 cm wide at the apex and 3.5 cm at the base, up to twice as long as the pileal diameter, more or less cylindrical, slightly widened towards the base, whitish floccose to smooth, in young basidiomata sometimes with a distinct cottony rim where the volva begins; volva robust, splitting into 2 to 4 lobes, up to 5 cm tall from stipe base to the upper lobe, saccate (type IV) rarely vaginate (type III), not or only slightly constricted at the base, membranous, up to 3 mm thick, in mature basidiomata sometimes receding, usually entirely whitish, sometimes with small ochraceous spots on the outer face, rarely entirely yellowish ochraceous coloured, whitish on the interior face, outer surface sometimes rugulose; limbus internus present. Lamellae adnexed, truncate, up to 10 mm broad, white or whitish, sometimes salmon upon drying, margin serrate, flocculose, concolorous with the sides; 0–2 tiers lamellulae. Spore print white. Odour indistinct or distinct, unpleasant, resembling A. strobiliformis to some extent. Taste not recorded. Macrochemical reactions: 10 % phenol on stipe, lamellae and context produced a purple colour; 5 % KOH was pale yellowish on the stipe surface and negative on the pileus, lamellae and stipe trama; 10 % NH 4 OH was negative on all tissues; tincture of guaiac was negative on all tissues.

Pileipellis an ixocutis about 100–150 µm thick, covered in some areas with a thin gelatinous layer containing hyphae 2–3 μm broad; the main layer is a homogeneous stratum consisting of hyphae 3 µm broad, helically arranged and forming a rope-like entangled, resistant bundle; presence of a few hyphae of thromboplerous type, strongly cyanophilous, 5–7 µm broad; hyphae of the pileipellis hyaline, but in 10 % KOH form a faintly yellow mass, seen in all collections examined (presumably residual shade of vacuolar pigment, colouring the hyphae in fresh state). Context of pileus consisting mainly of elongated physaloid elements of very variable size, for example, 190 × 35 µm, 70 × 20 µm or 45 × 22 µm; the shortest sometimes catenulate, held together by a network of hyphae 5–7 µm broad; the overall structure with matted aspect, without entanglement, very fragile. Basidia narrowly clavate to elongate clavate, 33–82 × 12–22 µm, mostly tetrasporic but with a significant proportion of bisporic basidia; sterigmata moderately to very thin, 2.5–6.5 µm long. Subhymenium mostly of inflated-ramose (type 2 of Bas 1969) to sometimes subcellular elements, the subhymenial cell supporting one to many basidia; the branches immediately below the basidia are fixed several on the lower branch. Lamellar trama 40–250 μm thick, with a mediostratum made of an undifferentiated material, whose elements are difficult to separate without breaking the most fragile and of which a few small oval physaloid cells, parallel to the axis are visible; hymenopodium indistinct. Lamellar edge sterile, covered with a gelatinous layer 30–40 µm thick, containing a few marginal cells; below this layer the basidia are partially mixed with marginal cells of the same shape, globose to subovoid, rarely pyriform 20–55 × 19.5–35 µm, with a pedicel of variable length and 3 µm wide. Universal veil (volva) 3-layered (on some individuals, one or the other external strata may be missing up to a certain height); a medium layer, covered by an outer and an inner stratum with a more compact structure; the main layer about 500–1500 µm thick, composed of loosely arranged hyphae, crossed by compact clusters of hyphae 3–5(–8) µm broad, very strongly entangled with each other and very strongly related to oval, medium-sized physaloid elements measuring, e.g., 50 × 20 µm, 60 × 35 µm, or 9 × 30 µm, or more rarely subspherical, e.g., 35 × 30 µm; filamentous hyphae abundant, inflated elements moderately abundant to common; both inner and outer strata, of variable thickness, are of the same composition with entanglement stronger than the main stratum, but a little less strong than clusters, resulting in a thick, moderately supple material; in cases when the volvas are thin, the structure of the middle stratum is tighter, more difficult to interpret and therefore less characteristic. Stipe trama essentially composed of vertically disposed, very long, slenderly clavate acrophysalids, 80–320 × 15–35 µm, ensuring the rigidity; these are the terminal members of predominantly vertical, quite short, 3–5 µm broad hyphae; on the inner wall of the usually hollow stipe, acrophysalid-like cells of spherical shape are present, contrasting with the acrophysalids of the context; those acrophysalid-like cells are sometimes agglomerated in a gelatinous in appearance matrix (possible pith precursors). Basidiospores mostly broadly ellipsoid or subglobose, usually with a single guttule, rarely pluriguttulate, (8.9–)9.1–13.8 (–16.8) × (7.4–)8.0–11.8(–13.6) µm, Q = (1.0–)1.05–1.36(–1.4), L av = 10.3–12.0, W av = 8.5–10.4, Q av =1.08–1.3 (n = 505, m = 13, p = 13). Microchemichal reactions: K–K reaction negative.

Habit and habitat:—Found from June to November in natural forests, plantations and parklands with trees of genus Populus Linnaeus (1754: 456) .

Additional specimens examined (paratypes):— BULGARIA. Sofia capital province, Sofia city, West Park, a lawn with Populus × canadensis and Pinus wallichiana , 42°42’10.3”N, 23°15’35.9”E, elev. ca 625 m, 11 June 2020, B. Assyov & I. Penchev (SOMF 30802!, LIP 0004526!, FBozok 1224!; nrITS: OR524134; nrLSU: OR512419; TEF-1α: OR526521); idem, 3 November 2020, B. Assyov (SOMF 30803! nrITS: OR524135); idem, 8 June 2021, I. Penchev (SOMF 30804!, LIP 0004525!, FBozok 1230!; nrITS OR524136); idem, 9 June 2021, Ts. Yordanova (SOMF 30805!; nrITS: OR524137); idem, 42°42’2.67”N, 23°15’15.60”E, elev. ca 645 m, mixed scrub, under P. × canadensis , 11 June 2020, B. Assyov & I. Penchev (SOMF 30806!; LIP 0004527!, FBozok 1223!; nrITS: OR524138); Sofia province, Novi Han municipality, in the vicinity of Karapoltsi village, 42°37’01.1”N, 23°42’16.8”E, elev. ca 585 m, under P. × canadensis , 7 July 2020, D. Dimitrova (SOMF 30807!, FBozok 1225!; nrITS: OR524139; nrLSU: OR524139); idem, 42°36’59.5”N, 23°42’15.9”E, elev. ca 585 m, in a grassland close to P. × canadensis , 8 June 2021, B. Assyov (SOMF 30808!, LIP 0004528!, FBozok 1228!; nrITS: OR524140); Pernik province, between Trun town and Ezdimirtsi village, 42°50’09.1”N, 22°41’28.0”E, elev. ca 800 m, forest of Populus tremula and Carpinus betulus , 5 September 2020, B. Assyov (SOMF 30809!; LIP 0004523!, FBozok 1227!; nrITS: OR524141); idem, 42°50’07.6”N, 22°41’28.2”E, elev. ca 805 m, 28 June 2021, B. Assyov (SOMF 30810!, LIP 0004522!, FBozok 1229!; nrITS: OR524142); CZECH REPUBLIC. Highland, ŽďÁr nad SÁzavou, in town, near ŽĎAS company compound, in grassplot and mineral soil under mature Populus nigra trees, on acid background but soil could have been influenced by artificial sources of calcium (e.g., mortar), 49°33’21.8”N, 15°55’49.9”E, elev. ca 580 m, 3 July 2010, J. Borovička & J. Kubrová (PRM 958042!, BRNM 829044!; nrITS: OR524132; nrLSU: OR524132); FRANCE. Hautes Pyrénées (65), Castet de Gerde, young recolonisation afforestation natural extension of a forest on calcareous soil with Betula pendula , Corylus avellana , Salix caprea and (a little further on) Populus tremula , 43°3’29.51”N, 0°10’2.39”E, elev. ca 630 m, 7 July 2013, G. Corriol (GC13070701, BBF!; nrITS: OR524143); TÜRKIYE. Ankara province, Çubuk province, between KıŞlacık and Yıldırım village, 40°25’51.8”N, 32°54’20.5”E, elev. ca 1548 m, plantation of Populus tremula , 17 June 2021, F. Bozok, H. Taşkın, M. Yarar (FBozok 1085!, FBozok 1097!; nrITS: OR524144 & OR524145).

Figures

FIGURE 3. Macromorphological features and variability of Amanita amplivelata. a. SOMF30801 (holotype), b–l. Paratypes: b–c SOMF30810, d SOMF30802, e SOMF30806, f SOMF30803, g FBozok1085, h FBozok1097, i SOMF30808, j–k PRM958042, l SOMF30804. In a, b, c, e, g and i note the prominent volva and in f and i–l the ample remnants of the general veil, which often turn ochraceous tinted. Photos: a–f, i, l B. Assyov, g–h F. Bozok, j–k J. Borovička.

FIGURE 4. Micromorphological features of Amanita amplivelata. a. Basidiospores; b. Pileipellis weakly dissociated; c. Subhymenium; d. Subhymenium with subglobose subhymenial cell; e. Lamellar trama; f. Lamelar edge with the loose gelatinous layer seen detached at the top of the photo; g. Stipe acrophysalids and hyphae; h. Stipe cells fixed on the inner wall. Photos by: a B. Assyov, c–h J.-M. Hanss. Scale bars: a = 10 μm; b–d = 20 μm; f, h = 50 μm; e, g = 100 μm.