E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
The Melanoleuca melaleuca group as we use it here is characterized by a smooth, hygrophanous, dark brown to grayish brown cap, often with a low umbo, close to crowded, white mature gills, and a straight stem. |The group here does not include microscopic criteria about the presence and type of cystidia or about the spores (although the spores are amyloid and warted as in other Melanoleuca taxa). This is similar to the Melanoleuca melaleuca group in Arora(1) except that he specifies cystidia. Siegel(2) also includes a Melanoleuca melaleuca group - cystidia are described as "long and often pointed, tipped with barblike crystals". |Breitenbach(3) said that there are two interpretations of Melanoleuca melaleuca: M. melaleuca sensu Bresinsky and Stangl (and sensu others) has abundant cheilocystidia and M. melaleuca sensu Kuhner lacks cystidia. The taxa with no cystidia would not fit with the concepts of Arora or Siegel(2) but similar collections do occur at least in British Columbia - O. Ceska applies the name Melanoleuca stridula to these collections on the Mushroom Observer website and vouchered at the University of British Columbia. Moreover, UNITE sequences using the name Melanoleuca melaleuca fall both within and outside the A3 clade of Vizzini(7) which is specified as having species that lack cystidia.

Melanoleuca melaleuca has been found at least in ID, AB, YT, AK, MT, and VA, (Gillman, using a concept with cystidia). Melanoleuca melaleuca has been reported from BC (Schalkwijk-Barendsen), from WA by Andrew Parker, pers. comm., from NWT (at Ft. Smith) and QC, (Bigelow), and also from Norway and Switzerland, (Gillman).

Cap:
2-8cm across, convex then flat to concave, "sometimes with broad, shallow umbo, often depressed around umbo"; gray brown, pale brown "wood brown" to brown, "snuff brown" to "Saccardo's umber", or fuscous, center sometimes darker; bald, dry, moist or viscid, (Gillman), 2-8cm across, convex then flattened, often slightly depressed with central umbo; hygrophanous, "dark brown when moist, drying to buff, center often darker"; dry, moist, smooth, (Phillips)

Flesh:
firm; white, darkening slightly at the cap cuticle, in stem white or tan to olive, (Gillman), thin; whitish in cap, flushed ocher brown from stem base upward, (Phillips)

Gills:
"usually notched but varying to adnate or even very slightly decurrent", close or crowded, narrow; white

Stem:
2-8cm x 0.3-0.6(1.2)cm, "equal or with a slightly swollen base, rather slender, stiff"; "whitish or with darker (brown) fibrils"; top sometimes minutely scaly or scurfy

Veil:
absent

Microscopic spores:
spores 6-8 x 4-5.5 microns, elliptic, finely warted, amyloid; cheilocystidia harpoon-like, [presumably no clamp connections]

Spore deposit:
white