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

BOLETUS

349

Stirps SUBVELUTIPES
KEY TO SPECIES
1. Many caulocystidia from the middle area of the stipe or above greatly
elongated to more or'less setiform (but thin-walled)............... 2
1. Caulocystidia clavate to fusoid-ventricose but neck seldom up to 30 M long... 4
2. Context pallid when fresh; hyphae in cortex of stipe with walls becoming dull brown in KOH as revived............. B. roseobadius
2. Context yellow................................... 3
3. Cuticular hyphae of pileus rusty brown to reddish as revived in Melzer's;
pileus dingy cinnamon at maturity.............. B. rufocinnamomeus
3. Cuticular hyphae red in Melzer's as revived; spores 11-15 x4-5 A.. B. subluridellus
4. Stipe typically with pruina arranged in a reticulate pattern near the
apex; pileus olive-yellow to olive and becoming subsquamulose over
the disc............................. B. pseudo-olivaceus
4. Not as above.................................... 5
5. Pileus and stipe dark madder-red........... see B. bicolor var. borealis
5. Not as above.................................. 6
6. Context white before changing to blue; pileus dark russet or brown;
spores 9-12 x 3.5-5 M (but mostly immature on type)....... B. spraguei
6. Context yellow before changing; pileus yellow, orange or red or these
colors mixed; spores larger than in the above choice.............. 7
7. Spores 14-18 (20) x 5-6.5 (8),j; pileus drying yellow and base of stipe
with dark red hairs........................B. subvelutipes Peck
7. Not with above combination of features............... B. erythropus
189. Boletus subluridellus Smith & Thiers, sp. nov.
Pileus 5-10 cm latus, convexus, demum late convexus, resinosus,
laete ruber vel badius, tactu obscure violaceus. Contextus laete citrinus
tactu violaceus. Tubuli 6-9 mm longi, lutei tactu violacei; pori carminei.
Stipes 4-9 cm longus, 1.5-2.3 cm crassus, laete citrinus tactu viride
caeruleus. Sporae 11-15 X 4-5.5 g. Specimen typicum in Herb. Univ.
Mich. conservatum est; prope Ypsilanti, September 3, 1961, legit Smith
6406.
Pileus 5-10 cm broad, convex to irregular in outline, becoming
broadly convex, margin inrolled at first, a very narrow sterile band
present; surface dry and resinous to the touch, velvety to unpolished,
not truly viscid, evenly "vermillion-red" to "bay" or at times orangered, instantly dark violet where touched, the surface often pock-marked.
Context bright lemon-yellow but instantly blue where cut, taste slightly
acid-metallic, odor none, FeSO4 blue parts turn yellow and then orange.