Amanita harkoneniana Fraiture & Saarimaeki

Fraiture, Andre, Amalfi, Mario, Raspe, Olivier, Kaya, Ertugrul, Akata, Ilgaz & Degreef, Jerome, 2019, Two new species of Amanitasect. Phalloideae from Africa, one of which is devoid of amatoxins and phallotoxins, MycoKeys 53, pp. 93-125 : 104-107

Amanita harkoneniana Fraiture & Saarimaeki sp. nov. Figs 5, 6

Diagnosis.

Amanita harkoneniana differs from the closest Amanita species by: pileus first whitish to pale yellowish-beige then entirely whitish, devoid of veil remnants, basal bulb of the stipe turnip-shaped or irregularly elongated and more or less rooting, basidiospores subglobose to widely ellipsoid (Q = 1.04 –1.13– 1.25), basidia 34 –37.5– 41 µm long and growth without connection with the genus Eucalyptus , in Tanzania and Madagascar.

Holotypus.

TANZANIA. Tabora District: ca. 10 km S of Tabora, Kipalapala, ca. 1200 m alt., 12 Dec. 1991, T. Saarimäki et al. 1061 (H!).

Description.

Primordium smooth, subglobose but with a more or less conical or irregular rooting part; veil whitish; pileus with a weak brownish tint (around 4B2-3 and 5B2-3 but paler). Pileus 35 –53– 70 mm diam., first hemispherical, then largely conical or convex to nearly applanate, often with a deflexed margin, without umbo; margin even, neither striate (sometimes striate on exsiccates) nor appendiculate; first whitish to pale yellowish-beige (between 4A2 and 4B2) then entirely whitish; slightly viscid when young, smooth, devoid of veil remnants. Lamellae white, becoming slightly yellowish when old and pale to dark brownish in exsiccates with a narrow white and fluffy edge, free, mixed with an equal number of lamellulae which are very variable in length and are usually truncated, sub-distant, 8-10 lamellae and lamellulae per cm at 1 cm from the edge of the pileus, about 125-215 lamellae + lamellulae in total (counts on 2 basidiomata), ventricose, very finely serrate when seen with a magnifying glass. Stipe 65-130 × 8-14 mm, sub-cylindrical, slightly wider just under the lamellae, gradually and slightly widened from top to bottom, white, with finely fibrillose surface, hollow (at least in exsiccates) or stuffed. Ring white, hanging, membranous but thin and fragile, upper part adhering to the stipe. Basal bulb of the stipe turnip-shaped or irregularly elongated, more or less rooting, surrounded by a white volva (also white inside), membranous, up to 40-60 mm high. Context white, soft, very thin along the margin of the pileus, much thicker near the stipe; smell weak resembling raw potato [Harkonen pers. comm.], very variable according to specimens but mostly of shellfish as in Russula xerampelina , especially for mature and old specimens [P. Pirot, pers. comm. about specimens from Madagascar], taste mild, then unpleasant [description of the Tanzanian specimen].

Basidiospores hyaline, with thin, rather weakly amyloid wall, (globose-) subglobose to widely ellipsoid (-ellipsoid), (6.5-) 7.0 –8.07– 8.6 (-10.0) × (6.0-) 6.5 –7.15– 8.0 (-8.5) µm, Q = (1.00-) 1.04 –1.13– 1.25 (-1.33) [53/3/2]. Basidia 4-spored, without clamp, clavate, often rather abruptly swollen, (30-) 34 –37.5– 41 (-46) × 9.0 –10.4– 11.0 (-13.0) µm, l/w = 3.00 –3.60– 4.40 (-4.90) [31/3/2]. Lamellar edge sterile, composed of marginal cells which are widely clavate to pyriform, hyaline, thin-walled, smooth, not clamped, 26 –32.2– 40 × 13 –16.8– 20 µm, l/w = 1.56 –1.93– 2.23 [10/1/1]. General veil (volva) mostly composed of cylindrical hyphae, with very different diameters, (20-) 33-50 (-110) × 4-11 (-15) µm, hyaline, with smooth and thin wall, septate but without clamps, with occasional anastomoses between parallel hyphae, branched, mixed with a few scattered hyaline sphaerocysts, globose to sphaeropedunculate or ellipsoid, 45 –75– 100 (-120) × (20-) 35 –57– 87 (-115) µm, l/w = 1.04 –1.38– 1.68 (-2.38), with a smooth and thin wall, rarely slightly thickened (<1 µm) [18/1/1].

Distribution.

Up to now, the species is only known from Tanzania and Madagascar. According to its ecology, it could potentially be observed in all regions occupied by the miombo woodland.

Ecology.

In miombo woodland (Tanzania) and in a garden, next to Cocos nucifera L., Citrus sp. ( “combava”), Tambourissa sp. and Psidium guajava L., along the Indian Ocean (Madagascar).

Etymology.

This species is dedicated to Prof. Marja Härkönen in acknowledgment of her tremendous contribution to African mycology.

Specimens examined.

MADAGASCAR. Prov. Toamasina: Mahambo, Dec. 2014, P.Pirot s.n. (BR); Ibidem, 2016, P.Pirot s.n. (BR). - TANZANIA. Tabora District: ca. 10 km S of Tabora, Kipalapala, ca. 1200 m alt., 12 Dec. 1991, T. Saarimäki et al. 1061 (holotype: H!).

Note.

We believe that the picture of " Amanita cfr. phalloides " presented by Ryvarden et al. (1994: 76-77) could be Amanita harkoneniana . The macroscopic description and the picture given by the authors correspond to the characters of that species. From this description, the fruit-bodies have a nauseous odour, are soon decaying and grow in miombo woodlands or in association with pine trees in the middle of the rainy season; they are rarely seen. No precise locality is given but the book covers South Central Africa (mostly Malawi, Zambia and Zimbabwe).

A comparison with the closely related species is given in the chapter “discussion” below.