The boletes of Michigan, by Alexander H. Smith and Harry D. Thiers.

BOLETUS

249

Spore deposit olive-brown; spores 10-13 X 4-5 I, smooth, apical
pore not evident, shape in face view somewhat fusiform, in profile somewhat inequilateral, color as revived in KOH pale olive-yellow, duller in
Melzer's as though weakly amyloid, wall 0.2 J thick.
Basidia 4-spored, narrowly clavate, 28-36 X 6-9 Mu, yellow in KOH
fading to. hyaline, yellowish in Melzer's. Pleurocystidia scattered,
34-55 X 6-11 gL, narrowly fusoid-ventricose, neck in some flexuous, hyaline to yellow in KOH, wall thin and smooth. Cheilocystidia smaller
than pleurocystidia and necks shorter. Caulocystidia 35-60 X 9-15 g,
clavate, thin-walled, hyaline in KOH, wall thin and smooth, fasciculate.
Tube trama of the Xerocomus subtype (weakly divergent), the hyphae tubular, 7-12 g wide and septa refractive in KOH, no fleeting-amyloid reaction present in the trama (though possibly a weak reaction on the
spores). Pileus cuticle a trichodermium of hyphae 6-12 (15) A in diameter, hyaline in KOH and in Melzer's, end-cells often short and bullet-like,
both short and long cells present and a tendency for them to disarticulate is evident, walls smooth or nearly so (either in KOH or in Melzer's).
Hyphae of subcutis and adjacent context with orange-cinnabar content
as revived in Melzer's but slowly fading to orange-ochraceous, walls
smooth, hyphae more or less tubular and 5-12 u wide. Clamp connections absent.
Habit, habitat, and distribution.-Mackinaw City area, Emmet
County, July 4, 1968, H. D. Thiers (Smith 75467).
Observations.-This species is unusual because the hyphae of the
subcutis as revived in Melzer's have such brightly colored contents,
whereas the elements of the trichodermium show relatively little color.
In addition, the small pores are a good field character for distinguishing
it from B. illudens, to which it seems related. It is also close to B.
spadiceus var. gracilis, but has smaller pores.
Stirps TENAX
130. Boletus tenax Smith & Thiers, sp. nov.
Illus. Pls. 102-3 (upper).
Pileus 4-10 cm latus, convexus demum planus vel late depressus,
siccus, velutinus, olivaceo-brunneus demum lateritius vel obscure roseus.
Contextus pallidus tactu tarde subvinaceus. Tubuli circa 12 mm longi,