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

354

THE BOLETES OF MICHIGAN

Tube trama typical for the section. Pileus cutis of appressed nongelatinous hyphae 3-6 p wide, tubular, the walls smooth to irregular but
hyaline or nearly so, terminal cell tubular or apex tapered slightly; an
olive-yellow pigment diffusing in mounts of KOH. Clamp connections
absent. All hyphae inamyloid.
Habit, habitat, and distribution.-Scattered at edge of a hardwood
forest under Corylus bushes and near them; Mackinaw City hardwoods,
July 12, 1967, Samuel Mazzer, James Bennett, and A. H. Smith 74510,
74511, and 74361.
Observations.-This species differs from B. subvelutipes in lacking
hairs at the base of the stipe, in having dark maroon-red pores regularly,
olive tones in the pileus and as dried the whole basidiocarp is a dingy
olive-yellow. The appressed-fibrillose scurfy pileus surface which becomes somewhat fibrillose-squamulose by maturity is a good field character also.
This species is most similar to B. queletii as described by Singer
(1967), though for a time we regarded it as a variety of B. subvelutipes.
However, Singer stated that it was: "ohne jede Netzzeichnung" and that
the pruina on the stipe was "sehr fein." In B. pseudo-olivaceus the stipe
is conspicuously pruinose and the pruina is often so arranged as to cause
the stipe to appear reticulate, but no veins of tissue are present-just
denser aggregations of pruina. The pores are a dark maroon-red overall
when young. The pileus cuticle is more of a cutis of appressed filaments
than a trichodermium, and in age it breaks up to produce an areolate to
fibrillose scaly condition.
Both B. subvelutipes and B. pseudo-olivaceus grow in the same
habitats, and we suspect that there has been gene exchange between
them, but the problem needs critical study over a period of years to
elucidate it. This whole stirps has always been and will continue to be in
the forseeable future, a confusing group because of the "spatter pattern"
of the distribution of the characters between the various populations
discovered.
192. Boletus roseobadius Smith & Thiers, sp. nov.
Pileus circa 12 cm latus, convexus, siccus, obscure roseus. Contextus pallidus tactu violaceus. Tubuli 12 mm longi, lutei vel crocei; pori
coccinei. Stipes circa 10 cm longus, 15 mm crassus, roseo-pruinosus,
fractu violaceus, non-reticulatus. Sporae 13-16 X 5-6.5 p. Specimen
typicum in Herb. Univ. Mich. conservatum est; prope Ann Arbor,
September 20, 1965, legit Florence Hoseney (Smith 72668).