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

364

THE BOLETES OF MICHIGAN

Habit, habitat, and distribution.-This species is rare in Michigan.
Kauffman collected it near Marquette, which is a region rich in boletes.
Observations.-This is a distinctive species readily recognized by
the colors and the almost hymeniform cuticle formed by the enlarged
end-cells of the trichodermial elements. The spores are narrower than for
the typical form of B. edulis, with which species it is classified as a
subspecies by Singer (1967).
The following data were obtained from the type: Spores 13-16 X
3.5-4.5 (5) p, smooth, lacking apical differentiation, shape in face view
narrowly subfusoid, the ends obtuse, in profile obscurely inequilateral,
suprahilar depression often very shallow; color in KOH weakly ochraceous, in Melzer's bay-red (dextrinoid), wall about 0.3 / thick.
Basidia 4-spored, 7-10 p wide, weakly yellowish in KOH, many
small yellow globules present along the hymenium in mounts in
Melzer's. Pleurocystidia rare, 32-45 X 8-13 /M, fusoid-ventricose, neck
often elongated and apex subacute, yellow in KOH or in Melzer's, content homogeneous in Melzer's. Cheilocystidia mostly resembling basidioles or a little wider (6-12 g), soon gelatinizing in KOH.
Tube trama of the Boletus subtype, hyphae lacking any amyloid
content or walls and tissue brown as viewed in Melzer's against a white
background. Pileus cuticle a hymeniform layer of pear-shaped to clavate
end-cells 32-50 X 9-12p, walls thin and smooth, content yellow in
KOH or Melzer's, no amyloid inclusions present, also in the layer are
numerous pileocystidia 40-80 X 9-16, or occasionally larger, often
multicellular in the neck, smooth, thin-walled and content yellow in
Melzer's. Hyphae of subcutis yellow to orange in Melzer's. Clamp connections absent.
Notes: There are more multiseptate pileocystidia in the type than
in the Michigan collections, but this hardly justifies recognizing the
latter as a distinct taxon. There were faint suggestions of a greenish
reaction in KOH on the cuticular elements, but it was not distinctive.
Boletus nobilis Peck is the same as B. separans microscopically.
The numerous minute oil droplets along the hymenium and throughout
the mount are present in Melzer's, the lack of any amyloid reactions in
the hyphae or their walls is similar, the spore size and most of all the
details of the cuticle of the pileus are alike in both.