SUBSECTION HYGROPHORUS 295 



178 



Hygrophorus adiaphorus, sp. nov. 



Pileus 1.5-3 cm latus, obtusus deinde fcnnc planus, plerumque urn- 

 bonatus, fibrillosus, glutinosus, medio fuscus demum subniger, margine 

 cineraceus; lamellae distantes, medio-latae, adnatae demum decur- 



rcntes, albae; stipes 3.5-6 cm longus, 4-7 mm crassus, albus ei serious 



supeme, cinercus demum fumeus infra; sporae 9-12 X 5-6.5 //. sub- 

 ellipsoideae demum oblongae. Specimen tijpicum in Herb. Univ. 

 Mich.; ledum Wilderness State Park, Oct. 15, 1960, Smith 63359. 



Pileus 1.5-3 cm broad, obtuse becoming nearly plane but usually 

 retaining a slight umbo, surface streaked with fine dark fibrils beneath 

 a coating of slime, disc fuscous to blackish, gray to cinereous at margin; 

 context white, fragile, odor not distinctive. 



Lamellae distant, moderately broad, broadly adnate to short de- 

 current, waxy white, drying creamy-pallid or the edges yellowish. 



Stipe 3.5-6 cm long, 4-7 mm thick, equal, solid, white and silky 

 over apical fourth, lower three-fourths covered by a slime coating giv- 

 ing a gray to umber tone to that part, and this tone mostly preserved in 

 drving, no inner fibrillose veil present. 



Spores 9-12 X 5-6.5 fx, subelliptic to oblong or one end slightly 

 broader than the other, smooth, hyaline in KOH and merely yellowish 

 in Melzer's solution. Basidia 2-spored, 38-52 X 5-7 /x, in KOH seen to 

 contain many oil drops, reddish in Melzer's reagent. Pleurocystidia and 

 cheilocvstidia none. Gill trama of divergent hvphae. Pileus epicutis of 

 appressed but interwoven narrow (2-4 /x) gelatinous hvphae hyaline to 

 dingv yellowish in KOH. Clamp connections absent (but bumps on hv- 

 phae near the cross walls often occur on epicuticular hvphae). 



Habit, Habitat, and Distbibutiox — Solitary under spruce and fir, 

 Wilderness State Park, Emmet County, Mich., Oct. 15, 1960. 



Material Studied — Michigan: Smith 63359, type. 



Observations — This species is easily mistaken in the field 

 for H. megasporus, and closely resembles the slender form of H. oliva- 

 ceoalbus though a fibrillose inner veil is not present beneath the gluten 

 of the stipe. It is this nondescript appearance which we have chosen to 

 emphasize in our choice of a species epithet. Its claim to distinction is 

 based on the lack of clamp connections on the hvphae of the carpo- 

 phore and the relatively small spores (for this group) on 2-spored 

 basidia. The lack of clamps in a species in this series is a matter 

 of considerable theoretical interest in view of the situation which has 

 been found in other sections of this subgenus. 



