North American species of Lactarius / L. R. Hesler, Alexander H. Smith.

Subgenus Piperites

265

Observations.-The horribly acrid taste, changing color of the
gills from pallid to dull vinaceous by old age, unchanging latex, and
(so far at least) no (or very few) scrobiculi on the stipe, distinguish it.
The spore ornamentation distinguishes it from L. insulsus ss. Neuhoff,
as does the gill color in age.
Material cited.-MISSISSIPPI: Guravich9,169,389 (type, MICH),
732 (all MICH).
86. Lactarius sanmiguelensis sp. nov.
Pileus 8-15 cm latus, plano-depressus demum late infundibuliformis, zonatus, zonae pallide alutaceae, ad marginem praegossypinus; contextu crassus durus, inodorus; latex lacteus, constans, acerrimus; lamellae confertae, angustae, pallide alutaceae, non-maculatae;
stipes 6-8 cm longus, 2.5-3.5 cm crassus, siccus, scrobiculatus, pallide
alutaceus; sporae 6.5-8 X 5-6,u. Specimen typicum in Herbarium
University of Michigan conservatum, Smith 51924, legit prope Placerville, Colorado, 6 Aug 1956.
Pileus 8-15 cm broad, plano-depressed with the margin incurved,
expanding to broadly vase-shaped, zonate, cinnamon-buff zones on a
pinkish buff ground color, glabrous over disc, margin with a heavy
roll of soft felt which is pale pinkish buff or nearly so. Context thick,
very hard, odor not distinctive; latex milk-white and unchanging, not
staining, instantly very strongly acrid.
Lamellae close to crowded, narrow, adnate, pinkish buff or nearly
so, not discoloring where injured, much anastomosed.
Stipe 6-8 cm long, 2.5-3.5 cm thick, clavate, with depressed
pinkish buff watery spots (scrobiculate), remainder of surface pale
pinkish buff and ~ unpolished, in age ~ pinkish buff overall.
Spore deposit not obtained. Spores 6.5-8 X 5-6 u, ellipsoid; with
a distinct plage usually lacking diffusely distributed amyloid material;
ornamentation in the form of a partial to broken reticulum or
reticulum not evident, the ridges mostly isolated, isolated warts also
present, prominences 0.5,u high.
Basidia 45-52 X 8-10,u, 4-spored. Pleurocystidia: macrocystidia
of the intermediate type not clearly distinct from pseudocystidia in
many instances, numerous, mostly 40-67 X 5-8,u, ~ fusoid, walls often
undulating, apex + acute, with one or more subapical constrictions,
content granular. Cheilocystidia 37-45 X 6-7.5 Mu, similar to pleurocystidia. Gill trama lacking rosettes; lactifers pale yellow in KOH.
Pileus trama heteromerous; lactifers yellowish in KOH, content striate
to granular. Pileus cuticle over disc an ixocutis ~ 70, thick; over