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Basionym: Boletus gracilis Peck, Rept. N. Y. State Mus. 24: 78. 1872.
Porphyrellus gracilis (Peck) Singer, Farlowia 2: 121. 1945.
Tylopilus gracilis (Peck) Henn., in Engler & Prantl, Nat. Pflanzenfamilien 1: 190. 1897.
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| Description： |
Pileus 3-5 cm broad, hemispheric to convex; surface dry and granulose in young and areo-late in old, chestnut-brown or paler but often in cinnamon color except for the pale flesh showing in areolate pilei; margin with a very narrow sterile band; context up to 0.8 cm thick, white to pallid or tinged incarnate near the cuticle, unchanging when bruised or cut, floccose but soft to the touch, taste mild, odor not distinctive. Tubes up to 10 mm deep, deeper than flesh of pileus, deeply depressed around the stipe, color white to pallid, becoming flesh col-ored to vinaceous. Pores each 1 mm, brownish color when bruised. Stipe 6-12 cm long, 4-7 mm thick at apex, 0.8-1.5 cm at base, much longer than width of pileus, often curved, surface finely granular to pruinose, often with longitudinally striates; color white at apex, white mycelioid at base, the remaining areas nearly similar to the color of pileus in well-developed basidiocarps but often with a paler cinnamon-tan, solid; context white, unchanging when bruised. Spore deposits dark purplish or vinaceous brown; spores (10)14-15(15.5) × 5-6(7) μm, narrowly ovoid to subelliptic in face view and inequilateral in profile view, smooth, thick-walled, greenish in KOH, yellow ochre in Melzer,s with about 20% dextrinoid. Basidia with 2- or 4-spores, each 36-42 × 10-15 μm, hyaline in KOH, yellowish in Melzer,s. Pleurocystidia scattered, 35-50 × 6-9 μm in length, narrowly fusoid-ventricose with gradually tapered neck and subacute or obtuse apex, thin-walled, hyaline in KOH and Melzer,s. Tube trama gelatinous and divergent, hyphae nonamyloid. Pileus cuticle with a trichodermium of hyphae 8-10 μm in diameter, the terminal cells nonamyloid but often more or less cystidioid, hyaline or yellowish in KOH; hyphae in subcutis 5-8 μm thick. Surface of stipe a layer of interwoven hyphae or suberect hyphae; tip cells contorted to cystidioid (fig.2d). Clamp connections absent. |
| Specimens： |
Taiwan, Chiai: Da-Tung-Shan, alt. 1,500 m, 14 Jun 2002, Chen CM. 3243. |
| Note： |
Tylopilus gracilis (Peck) Henn. is easily confused with Austroboletus gracilis (Peck) Wolfe. Both species share the same character of a long slender stipe, and once were consid-ered to be synonymous to Boletus gracilis Peck. Smith and Thiers (1971) described the spores of Tylopilus gracilis as " punctate (under oil-immersion lens) in many spores," while Grund and Harrison (1976) found that the spores are smooth, but "the peculiar punctate spores, seen in some collections under high magnification, are unusual in Tylopilus." Thereafter, Wolfe (1979) proposed the genus Austroboletus, based on the result of EM scanning observation, to include those of T. gracilis that have the spores "with an inconspicuous hyaline sheath, inner colored wall with minute canals ending in the pits at the surface" described by Smith and Thiers (1971). In addition, they are distinguishable by their shape of pleurocystidia: narrowly fusoid-ventricose with gradually tapered neck for T. gracillis and clavate for A. gracilis. Also, the spores of T. gracilis are distinctivelylonger (14-15 μm) than those of A. gracilis (7-9.5 μm). |
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Phylum：Basidiomycota >> Class： Basidiomycetes >> Order： Boletales