Melanoleuca juliannae Rimóczi, Antonín, L. Nagy & Tomšovský, 2014

Antonín, Vladimír, Benedek, Imre Rimóczi Lajos, Papp, Viktor, Szarkándi, János Gergő, Dima, Bálint, Nagy, László G., Papp, Tamás, Ďuriška, Ondrej & Tomšovský, Michal, 2014, Melanoleuca juliannae (Basidiomycota, Tricholomataceae), a new species from subgen. Urticocystis, Phytotaxa 170 (1), pp. 13-23 : 16-18

Melanoleuca juliannae Rimóczi, Antonín, L. Nagy & Tomšovský , sp. nov. ( FIGURES 2–4 )

MycoBank MB 808033

Pileus (20–)40–60(–95) mm, dark greyish brown, then melleous to pale deer-brown. Lamellae off-white to pale beige or pale grey. Stipe (20–)30–60(–70) × 2–6(–7) mm, pale yellow-brown, darker towards base with greyish blue or steel blue tones. Context with greyish blue or steel blue tinge at stipe base. Basidiospores (7.0–)8.0–10(–12) × 5.0–7.0 μm, (broadly) ellipsoid or ellipsoidfusoid, subovoid, verruculose, rarely with small ridges. Cheilocystidia urticoid, 28–49 × (5.0–)6.0–11 μm. Pileipellis an ixocutis. Caulohymenium developed.

Holotype:— HUNGARY, Budapest, RÁkospalota, 29 November 2013 I. Rimóczi ( BP 104371; Isotype BRNM 751957 ).

Etymology:—Dedicated to the collector’s mother, who supported his first steps in mycology.

Pileus (20–)40–60(–95) mm broad, slightly convex with small central umbo and involute margin when young, then applanate to slightly infundibuliform with indistinct to rather distinct umbo and straight or revolute margin, dull, smooth, rarely slightly felty at centre, otherwise innately fibrillose, especially when old. Margin non-grooved or slightly grooved in old specimens, dark greyish brown when young (and also in wet older basidiocarps), then melleous to pale deer-brown with darker centre. Lamellae medium to almost crowded, 2–6(–8) mm wide, narrowly to broadly adnate, off-white to pale beige or pale grey (but may have slight blue tinge when old), with even concolorous edge. Stipe (20–)30–60(–70) × 2–6(–7) mm, straight, cylindrical, sometimes slightly broadened at apex and/or at base, hard in touch, floccose-felty at apex, longitudinally fibrillose to fibrillose-squamulose otherwise, pale yellow-brown, darker towards base with ± distinct greyish blue or steel blue tinge, sometimes blue colour ascending towards stipe apex, at base with poor pallid tomentum and covered with distinct sandy cover. Context very thin and soft in pileus, fibrillose-stuffed, then hollow in stipe, off-white when young, then becoming pale greyish beige under pileipellis and near lamellae, silky white in stipe in very young specimens, then quickly turning pale brownish grey in upper part and darker greyish brown towards base; at base, the colour becomes gradually violaceous-blue and then almost blackish blue at very base; dark blue colour of stipitipellis often runs upwards; bluish colour of the stipe context is also distinct in exsiccates. Smell and taste indistinct.

Basidiospores (7.0–)8.0–10(–12) × 5.0–7.0 μm, average = 9.0 × 6.0 μm, E = 1.30–1.90, Q = (1.43–)1.57–1.64, (broadly) ellipsoid, ellipsoid-fusoid, or subovoid, verruculose, rarely with small ridges, warts regular or irregular in shape and variable in size, up to 0.5–0.75 μm broad and 0.25–0.34 μm high, amyloid. Basidia 32–41(–48) × 9.0–13 μm, 4-spored, clavate. Basidioles 15–40 × 4.5–13 μm, clavate, cylindrical, rarely subfusoid. Cheilocystidia urticoid, 28–49 × (5.0–)6.0–11 μm, of two types: the exscissa - type more common, basal part often (sub)fusoid; the brevipes - type less frequent, basal part clavate to subvesiculose; apical part of both types 2.0–5.0 μm wide at base, subulate to cylindrical, thin-walled, mostly not muricate. Marginal cells 19–31(–44) × 8.0–11(–17) μm, clavate, fusoid, subpyriform, utriform, ± thin-walled, regular or irregular. Pleurocystidia absent. Trama hyphae cylindrical, thinwalled, hyaline, non-dextrinoid, up to 15 μm wide. Pileipellis an ixocutis composed of radially arranged, ± thin-walled, gelatinized, non-dextrinoid, up to 9.0 μm wide hyphae; terminal cells adpressed to erect, cylindrical or subclavate, ± thin-walled, obtuse, sometimes slightly irregular, 5.0–15 μm wide, ochraceous brown to ochraceous-grey in KOH. Stipitipellis a cutis of cylindrical, parallel, slightly thick-walled, 3.0–6.0 μm wide hyphae, pale yellow-brown in KOH. Caulohymenium of (1) 20–40(–55) × (6.0–)9.0–12 μm, clavate, cylindrical, thin-walled cells, (2) 32–46 × 8.0–13 μm, urticoid cystidia similar to cheilocystidia, and (3) 24–32 × 10–13 μm, caulobasidia, 4-spored, cylindrical to clavate; urticoid caulocystidia and caulobasidia may be rare or even absent. Clamp connections absent.

Habitat:—Single or in small groups on sandy soil in Festucetum vaginatae stipetosum, Junipero -Populetum albae, and secondary Brometum tectorum associations. All up-to-now known localities belong to the Eupannonicum floristical district of the Pannonian floristical province. Typical for them are loose sandy soils poor in humus (1–2 %), with xeric surface soils rich in chalk.

Material studied:— HUNGARY. Budapest , RÁkospalota, 29 November 2013, I. Rimóczi (holotype BP 104371, isotype BRNM 751957 ). Pest County : Kiskunság National Park, Örkény, 30 September 2005, I. Rimóczi ( BRNM 751958 and BP 104372). Ibid. , 13 November 2012, I. Rimóczi ( BP 104373). Bács-Kiskun County : Kiskunság National Park, Orgovány, 14 June 2006, I. Rimóczi ( BRNM 751959 and BP 104374). Kiskunság National Park , Fülöpháza, 9 June 2006, I. Rimóczi ( BP 104375). Ibid., 9 June 2006, I. Rimóczi and L. Nagy NL-5202 (Herbarium of the University of Szeged) .

Remarks:— Melanoleuca juliannae is characterized by a violaceous-blue stipe context, which represents an unique feature in this genus. Additionally it has moderately large (broadly) ellipsoid, ellipsoid-fusoid, subovoid, verruculose basidiospores, urticoid cheilocystidia of two types (exscissa - type most frequent), and a caulohymenium. Is seems to grow exclusively in primary and secondary xerothermic sandy habitats. Because of the urticoid cheilocystidia, Melanoleuca juliannae belongs to subgen. Urticocystis Boekhout (1988: 400).

The collection by I. Rimóczi and L. Nagy (NL-5202) differs from other ones by the presence of both 4- and 2- spored basidia and slightly larger basidiospores (8.5–10.5 × 6.0– 7.5 µm, average = 9.4 × 6.7 μm); other characters fully agree with the type specimen.

Melanoleuca juliannae seems to be a thermophilic species restricted to dry sandy stands. It forms, however, its basidiocarps till the first late autumnal frosts there. The type locality near Rákospalota in the periphery of Budapest is located at the north-eastern border of the Eupannonicum. It is surrounded with Pinus nigra plantations, roadways and residential areas. It is a non-forested area of ca. 25–35 ha, not used for mowing or grazing. In this degraded site, a few species characteristic of open sand steppes have survived together with several disturbance-tolerant species ( Eryngium campestre , Euphorbia seguieriana , Gypsophila paniculata ). In addition, there are abundant introduced species including Ambrosia artemisiifolia , Conyza canadensis , and Tragus racemosus . A strikingly large number of Phallus hadriani specimens grow together with M. juliannae on this site. The locality near Örkény represents a short-grassed, drought tolerant, perennial, open (plant cover below 75%), calcareous sand steppe of the Festucetum vaginatae association. The accompanying fungal species were Clitocybe herbarum , C. subcordispora , Crinipellis scabella , Disciseda bovista , Geastrum schmidelii , Phallus hadriani , Psathyrella ammophila , and Tulostoma melanocyclum ( Rimóczi et al. 2011) . The localities near Fülöpháza and Orgovány represent an open Junipero-Populetum albae forming a mosaic with Festucetum vaginatae stipetosum, with the same characteristic species as the Örkény stand. Some fungal species also present include Clitocybe glareosa , Cortinarius paracephalixus, Hebeloma ammophilum, Hygrocybe subglobispora ( H. acutoconia var. konradii ), Inocybe mytiliodora , Peziza ammophila , and Pseudoomphalina kalchbrenneri . Melanoleuca juliannae formed its basidiocarps at the centre of clearings on the slopes of sandy hills as well as near the trees Populus alba or Populus × canescens.

Figures

FIGURE 2. Melanoleuca juliannae (Holotype). Hungary, Budapest, Rákospalota, 29 November 2013. Photo I. Rimóczi (larger photo) and I. Rimóczi and V. Papp (inset).

FIGURE 3. Melanoleuca juliannae. SEM microphotographs of basidiospores (left: Holotype, right: BRNM 751959). Photo L. Ilkovics.

FIGURE 4. Melanoleuca juliannae. a. cheilocystidia, b. basidiospores, c. caulohymenium. Scale bar = 20 μm. Drawings V. Antonín.