Amanita rhacopus Y. Lamoureux

Lambert, Herman, Fortin, Guy, Labbe, Roland, Labrecque, Jacqueline, Berube, Jean A., Landry, Jacques, Ilyukhin, Evgeny, Margaritescu, Simona, Moncalvo, Jean-Marc & Lamoureux, Yves, 2018, Validation of two Amanita species from eastern North America: A. rhacopus sp. nov. and A. variicolor sp. nov., MycoKeys 38, pp. 47-57 : 47

Amanita rhacopus Y. Lamoureux sp. nov. Fig. 1

A. inaurata ss. Pomerl. p. p.; A. ceciliae ss. auct. amer. p. p.

non Amanita inaurata Secr. ex Gillet, Hyménomycètes ( Alençon): 41 (1874) [1878]

non Agaricus ceciliae Berk. & Broome, Ann. Mag. nat. Hist., Ser. 2 13: 396 (1854)

Diagnosis.

Amanita rhacopus differs from other species of Amanita section Vaginatae by its brown to dark grey-brown pileus, stipe white at times covered with grey chevrons, universal veil grey leaving small to large flakes on pileus and annulus-like remnants at the stipe base, found in stands of conifers ( Abies , Picea , Pinus , Tsuga ) mixed with Betula .

Holotype.

CANADA, Québec: Mont Orford, in mountain, close to a stand of Betula papyrifera in a Abies balsamea and Tsuga canadensis forest, 45°18'43" North, 72°14'24" West, 11 July 1994, CMMF002171, ITS Genbank accession number MG734660.

Description. Pileus 40-80 mm wide, ovoid to rounded conic slightly umbonate to applanate, smooth, brown to greyish-brown, with time darker in the centre and over inner ends of marginal striations, often with grey velar flakes, margin striated. Lamellae free, crowded, greyish near the pileus margin or completely greyish with age, lamellulae numerous, truncated, of very diverse lengths, unevenly distributed, edges finely powdered, white to whitish. Stipe 70-120 × 7-13 mm, cylindrical (not bulbous), flocculose and white first, then smooth to appressed fibrillose, whitish to greyish, at times with chevron-forming greyish fibrils, without annulus, with grey annulus-like remnants at the base. Universal veil friable, grey, leaving flakes on the pileus and annulus-like remnants at the stipe base. Partial veil absent. Context whitish, unchanging when cut or bruised, odour and taste not distinctive.

Basidiospores [474/11/10] (8.4) 9.5-11.7 (14.5) × (7.9) 9.0-11.1 (13.7) µm, Q= 1.0-1.1(1.2), Qm=1.05, globose to subglobose, smooth, monoguttulate, hyaline, inamyloid and cyanophilous. Basidia (50) 60-75 × 14-16 (18) µm, clavate, usually 4-spored with 4-6 μm long sterigmata, occasionally 2-spored with 5-10 µm long sterigmata, clampless. Subhymenium composed of irregular globose to subglobose 9-18 × 6-9 µm cells. Lamellar trama bilateral consisting of cylindro-clavate, clavate, fusiform to subfusiform, abundantly inflated cells 40-65 × 7-18 µm, mixed with thin-walled, hyaline, 3-6 μm wide filamentous hyphae and of rare 3-6 µm wide, sinuous vascular hyphae. Volva remnants composed of short 3-7 µm wide filamentous ramified hyphae, numerous 25-50 µm wide terminal globose cells (few subglobose), rare to absent vascular hyphae. Pileipellis composed of 4-12 µm wide interwoven gelatinised brown filamentous hyphae mixed with an equal amount of 45-100 × 8-22 µm inflated cylindrical cells, often in chains and some 4-7.5 µm wide vascular hyphae. Pileus context composed of 4-12 µm wide filamentous sometimes partially inflated hyphae and 70-170 × 15-30 µm cylindrical to clavate inflated cells, often in chains with cells of the same diam. and some 4-8.5 µm wide vascular hyphae, ramified and distributed in all parts of the context. Stipitipellis composed of 40-180 (270) × (16) 20-30 (35) µm clavate terminal cells with grey pigment encrusted wall, originating from undifferentiated 4-6 µm wide hyphae. Stipe context composed mainly of 120-360 × 20-50 µm cylindrical cells in chains with ramified 3-5 µm wide filamentous hyphae and 4-7 µm (apex) and 5-23 µm (centre) wide vascular hyphae. Clamps absent.

Ecology and distribution.

Solitary or scattered in stands of conifers ( Abies , Picea , Pinus ) mixed with Betula , on mesic to sub-mesic soil, never seen in plantations, from July to September in Québec and, according to sequences in Genbank, in all eastern North America down to Tennessee and Texas.

Etymology.

The epithet rhacopus refers to the Greek ῤάκος, meaning piece of cloth and πούς, meaning foot.

Specimens examined.

Canada, Québec: Québec, Boisé de l’aéroport, R. Labbé (RLA30465), 4 August 2007. Québec, Base de plein air La Découverte, H. Lambert (HL0787), 10 July 2010. Sainte-Catherine-de-la-Jacques-Cartier, Station touristique Duchesnay (sentier 51), H. Lambert (HL002), 7 July 2012. Lac-Beauport, H.Lambert (HL016), 12 July 2008. Québec, Château-Bigot, H. Lambert (HL049), 21 September 2014 (Genbank accession number MG734661). Québec, Base de plein air La Découverte, H. Lambert (HL022), 7 July 2013. Lac-Beauport, Lac Neigette nord, J. Labrecque (CMMF009600), 24 July 2007. Lac-Beauport, Chemin de la Chapelle, J. Labrecque (CMMF008929), 11 August 2006. Québec, Boisé de l’aéroport, R. Labbé (RLA30063), 15 July 2006. Lac-Beauport, Chemin de la Chapelle, J. Labrecque (CMMF009640), 29 July 2007 (Genbank accession number MG734662). Saint-Raymond, lac Sept-Iles, R. Lebeuf (HRL1876), 27 September 2014 (Genbank accession number MG734658). Québec, Château-Bigot, H. Lambert (HL048), 21 September 2014 (Genbank accession number MG734663). Grondines, Highway 40, Renée Lebeuf (HRL0804), 19 August 2011 (Genbank accession number MG734664). Ontario: Algonquin Provincial Park, M. Didukh and B. Dentinger (TRTC156853), 29 September 2007 (Genbank accession number MG734659).