Boletellus exiguus T.W.Henkel & Fulgenzi

Filed As

Boletaceae
Boletellus exiguus T.W.Henkel & Fulgenzi ( isotype )

Collector(s)

T. W. Henkel 8696, 24 Jun 2004

Location

Guyana. Potaro-Siparuni. Pakaraima Mountains, Upper Potaro River Basin, in Dicymbe plot 3,.

Habitat

Rain forest. Dicymbe corymbosa. Solitary to scattered. Humic accumulations on large, living tree trunk.

Description

Pileus brunneus, juventute velutinus, postea subtiliter areolatus, 9-33 mm latus. Trama caerulescens ubi exposita. Stipes brunneus, subtiliter longitudinaliter striatus, cartilagineus, apice cum collo rubro, 7-34 x 1-4 mm. Basidiosporae olivaceae in massa, amygdaliformes, longitudinaliter porcatae, 10-15 x 7-9 µm. Fructificatio insidens trunco Dicymbe arborum. Pileus 9-33 (42) mm broad, convex to applanate, dark brown (7D7) throughout when young to chestnut brown (5D5-5E7) to yellow-tan (4E6) with age, velutinous, becoming finely squamulose and areolate when mature, less so over disk, tacky to dry; margin slightly inrolled when young, irregularly crenulate with age; trama 1-1.2 mm thick at margin, 1-2 mm over tubes, 2-2.5 mm over stipe, dingy-white, bluing rapidly with exposure, solid, less so with age. Odor minimal, pleasant; flavor mild. Tubes 1-2 mm long at margin, 2-7 mm centrally, 2-5 mm at stipe, broadly and shallowly depressed around stipe, of irregular lengths, concolorous with pores, rapidly blue-green (26E7) on exposure; pores lemon yellow (3A7) when young, maturing to olive-yellow (4C7-4C8), rapidly blue-green (26E7) with pressure, with prominent decurrent tooth 2-2.5 mm long, 0.5-2 per mm, subangular, radially elongate near stipe. Stipe 7-34 x 1-4 mm, subequal, gradually and slightly flaring to 2-4 mm at apex and base, typically curving outward and upward from Dicymbe trunk, cartilaginous, tan (5D6) to maroon-brown (10F6-10D8) throughout, with prominent red (10D8) zone over distal 1-2 mm of apex, darkening slightly with handling, finely longitudinally striate; extreme base with brown tomentum; trama red-maroon (10F6-10F8) in upper half, tan-brown (5D5) below, unchanging. Basidiospores olivaceous-brown (5F6-6F5) to dark olive-green (3F8) in medium to heavy deposit, 10-15 x 7-9 µm (mean 12.7 x 8.2 µm; n = 20), Q range = 1.2-2, (mean Q = 1.53), olive-golden in H2O and KOH, inamyloid, amygdaliform, with moderately thick single wall, uniguttulate, with 10-16 longitudinal ridges; ridges <1 µm tall, occasionally bifurcating, terminating at unequal lengths before the apex and thus leaving a smooth area, all ridges converging at hilar appendage; hilar appendage 0.5-1 µm long. Basidia 37-51 x 12-15 µm, subclavate, tapering gradually to base, hyaline in H2O and KOH, with numerous refractive globules pale yellow in H2O, lighter in KOH, with three or four sterigmata; sterigmata 2-4 mm long. Pleurocystidia infrequent, 65-85(100) x 14-20 µm, projecting 27-42 µm above the hymenial palisade, ventricose, thin-walled; wall hyaline in H2O and KOH, with golden incrustations evident in Melzer's. Hymenophoral trama boletoid, strongly divergent; mediostratum 37-54.3 µm wide, of many thin, slightly interwoven hyphae, these hyaline in H2O, gelatinized and hyaline in KOH, lateral stratum hyphae 6.2-9.8 µm wide, hyaline in H2O and KOH, nongelatinized. Pileipellis a derm consisting of angular cells with tufts of erect inflated terminal cells concentrated in the squamules; tufts 91.4-197.6 µm wide, in mass orange-yellow in H2O, paler in KOH; terminal cells 19.7-41.2 µm long, cylindrical or ventricose, rarely clavate or mucronate. Pileus trama interwoven; individual hyphae 6.1-11 µm wide, light golden in H2O, hyaline in KOH, regularly septate. Stipitipellis a densely interwoven trichodermial palisade of cylindrical elements with inflated terminal cells, in mass golden-orange in H2O, lighter in KOH; terminal cells projecting 24.7-38.3 µm, cylindrical to ventricose, concentrated on stipe striations. Stipe trama of densely interwoven hyphae, these 2-4.9 µm wide, faint golden in H2O, hyaline in KOH. Clamp connections absent. Macrochemical reactions: NH4OH immediately blood-red (9C8) on pileus, then fading within minutes to orange, negative on stipe and pores; KOH red-orange (9B8) on pileus then quickly becoming orange (6B8), red (8D8) on stipe; FeSO4 negative on pileus, dark blue-green (25F4) on tube mouths then fading to a dark olive-green (26F5), darkening stipe.

Identifiers

NY Barcode: 1034374

Occurrence ID: 0b92f6ba-38c5-45fa-88da-6419e222c959

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