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The Genus Inocybe  

[ Basidiomycetes > Agaricales > Cortinariaceae . . . ]

by Michael Kuo

So I'm sitting at the collection tables after a day of fungus hunting, surrounded by mushrooms, microscopes, keys, drying equipment, and mycologists. One mycologist pokes around in another mycologist's collection basket, inspecting, then holds up a little brown mushroom. "You brought in an Inocybe? Why?"

No one cares about Inocybes. With a few purple exceptions, they epitomize the label LBM (Little Brown Mushroom), and are characterized by their brown spore prints, their often conical and usually silky-to-hairy-to-scaly or lacerated caps, and their frequently characteristic odors. There are hundreds of them, and probably hundreds of undocumented, "cryptic" species. In fact Inocybe is often treated less as a genus of mycorrhizal mushrooms than as a mycological rite of passage; if you have not "put a name on" a few Inocybes at some point in your life, good luck getting your (Myco-) Country Club membership. To me, all of this suggests that Inocybe is a prime candidate for demystification. Using a microscope isn't that hard, for crying out loud--and acquiring obscure mycological literature is a relatively simple matter of Interlibrary Loan, even from your public library.

So let's grab our pitchforks and headed for the gated community known as Inocybe Heights. The key below has been under development since 2005; it covers the species that demonstrate purplish shades (anywhere on the mushroom), and the white species (added in 2007). Yes, I am delaying the hard ones with brown and yellowish caps. If you absolutely cannot wait to identify your little brown or yellow Inocybe (it may be several years until I finish the key--and by then some enterprising molecular biologist may well have determined that many or most of the current morphology-defined species are invalid), a list of technical and semi-technical Inocybe sources can be found at the bottom of the page.

The concept of Inocybe has held up amazingly well under DNA scrutiny, which has even supported many of the traditional divisions within the genus (subgenera, sections, and so on). There are some exceptions, of course, but the overall picture, originally painted on the two-dimensional canvas of morphology (physical features as determined with and without a microscope), has been given depth by DNA studies and is beginning to become a three-dimensional sculpture. Since the mushrooms are mycorrhizal, they have obviously evolved in close association with their symbiotic tree partners. While mycologists have not traditionally paid much attention to the documentation of mycorrhizal associations (the paper listed below by Cathy Cripps on "[t]he genus Inocybe in Montana aspen stands" [1997] is a notable exception), it may be the case that this kind of information will help to further elucidate speciation and evolution in Inocybe.

 

Entoloma geophylla var. lilacina

Inocybe rimosa

Inocybe geophylla var. lilacina


© MushroomExpert.Com




(Partial) Key to Morphology-Defined Inocybe Taxa in North America

Unlike most keys at MushroomExpert.Com, this key is frequently microscope-based. There is just no escaping the need for microscopic analysis with Inocybe. Source abbreviations refer to the references list below the key.


1.Lilac or purplish shades present somewhere on the mushroom.
2

1.Lilac or purplish shades absent.
20


2.Spores with nodules, warts, or spiny structures.
3

2.Spores not as above.
7


3.Cystidia absent from gill faces.
4

3.Cystidia present on gill faces.
5


4.Sterile cells on gill edges present but not projecting as cheilocystidia. (Note: Usually described as a brown species, but "frequenter purpureo tincto" according to Atkinson's original description.)
Inocybe leptophylla
ATK 212; GS7 263;
K1 449; K2 242; MK 109

4.True cheilocystidia present, 35-50 µ. (According to Atkinson, "pileo brunneo, purpureo-tincto.")
Inocybe leptophylla var. cystomarginata
see Inocybe leptophylla
ATK 212


5.Mature cap to 1 cm across, reddish brown; spores 8-10 µ long.
Inocybe fulvella
GS5 672

5.Mature cap larger than above, variously colored; spores shorter than above.
6


6.Cystidia with thin walls; cap pinkish brown but fading markedly as it dries out (hygrophanous).
Inocybe tubarioides
SSW 299; ATK 217

6.Cystidia with thick walls; cap whitish over the center, pale purplish gray elsewhere.
Inocybe albodisca
at Roger's Mushrooms
? = I. grammata
K1 462; SSW 300; S47 22;
GS5 670; S78


7.Cystidia absent from gill faces.
8

7.Cystidia present on gill faces.
9


8.Cap with a dark purplish brown central bump, purplish brown elsewhere; gills and stem discoloring pinkish.
Inocybe adaequata
= I. jurana
? = I. frumentacea, K1 454

8.Cap with a whitish or pale central bump, whitish to pale greenish or pinkish elsewhere; neither gills nor stem discoloring pinkish.
Inocybe vinosistipitata
GS7 269


9.Cap with lilac shades.
10

9.Cap without lilac shades.
11


10.Cap lilac to grayish lilac, fading to whitish; cystidia 40-60 µ long, fusoid-ventricose, with encrustations.

10.Cap brownish, sometimes with lilac hues; cystidia 50-80 µ long, almost capitate (with swollen ends), without encrustations.
Inocybe griseolilacina
at Roger's Mushrooms
C 676; SS 93


11.Cystidia with thin walls; stem with a grayish sheath and a purplish apex; cap grayish.
Inocybe fuscicothurnata
GS3 27

11.Cystidia with thick walls; stem variously colored but not sheathed; cap variously colored.
12


12.Stem with conspicuously contrasting brown or rusty red hairs.
13

12.Stem without hairs, or with pale hairs that do not contrast conspicuously.
14


13.Cap rusty red; spores 7-10 µ long; cystidia 60-80 µ long.
Inocybe pyrotricha
SSW 296; SS50 106

13.Cap brown; spores 9-11 µ long; cystidia 60-100 µ long.
Inocybe cincinnata
at Roger's Mushrooms
= I. phaeocomis v. major
C 680; S78


14.Cap creamy yellow to creamy buff, sometimes with a pale cinnamon center.
Inocybe picrosma
S78; SS50 102

14.Cap differently colored.
15


15.Most spores with length in the range 10-16 µ.
16

15.Most spores with length in the range 7-11 µ.
17


16.Cap maroon becoming brownish; flesh with a pinkish tinge; cheilocystidia projecting prominently.
Inocybe obscura var. rubens
S47 42

16.Cap brown to dark brown, becoming tawny; flesh not pinkish; cheilocystidia not projecting prominently.
Inocybe obscura
sensu Stuntz
JJ Wuilbaut photo
S47 40


17.Cap with a reddish brown center, pale brown elsewhere; cystidia 63 µ long or shorter; odor distinctive but not spermatic.
Inocybe personata
Yves Deneyer photo
GS5 681

17.Cap otherwise colored; some cystidia regularly longer than 63 µ; odor spermatic (or not recorded).
18


18."Gregarious or subcaespitose, 4-4.5 cm high; cap pale ochraceous-fulvous, convex then expanded, nearly gibbous, prominently squamulose and irregularly rimose, marginally smoothly radiating-rimulose, 2-2.5 cm wide; gills broadly sinuate-adnexed, ventricose, isabelline becoming rusty-fulvous; cystidia cylindric or ventricose, thick-walled, 50-70 x 10-16 µ; spores oval or subreniform, inequilateral, smooth, 8-10 x 5-6 µ; stem 4-5 mm thick, white below, violaceous above, minutely white-velutinous, not squamose, with a basal bulb whose membranous volva sometimes becomes free; flesh white above, violaceous below" (Atkinson, 1918; my translation from Latin, my emphasis).
Inocybe violaceoalbipes
ATK 217

18.Not completely as above.
19


19.Cystidia with apical, cystalized encrustations; stem base slightly enlarged.
Inocybe pusio
S78

19.Cystidia without crystalized encrustations; stem base not enlarged.
Inocybe griseolilacina
at Roger's Mushrooms
C 676; SS 93


20.Fresh, unfaded cap white, whitish, or slightly pinkish.
21

20.Cap more highly colored. (Key to be developed. Species pages at MushroomExpert.Com: Inocybe calospora, Inocybe hystrix, Inocybe lacera, Inocybe leptophylla, and Inocybe rimosa. See also the many Inocybe pages at Roger's Mushrooms.)
[To be developed.]


21.Cap with pinkish hues, and/or surfaces and flesh staining pinkish to reddish.
22

21.Cap not pinkish; pinkish to reddish staining absent.
25


22.Cap (and sometimes the stem) with pinkish coloration rather than pinkish staining or bruising; gills and flesh not staining pinkish; spores 10-12.5 x 5.5-6.5 µ, not nodulose, warty, or spiny; originally described under spruce and hemlock in Nova Scotia.
23

22.Pinkish to reddish hues on surfaces and flesh resulting from staining or bruising; spores variously sized and shaped; ecology and range various.
24


23.Odor fragrant, complex.
Inocybe aurora
GS3 24

23.Odor not distinctive.
Inocybe aurora var. inodorata
GS7 257


24.Odor fragrant.
Inocybe fraudans
at MykoWeb
= Inocybe pyriodora
K1 450; K2 244; SSW 296; A 459

24.Odor spermatic.
Inocybe whitei
= Inocybe pudica
= I. geophylla var. lateritia
= Inocybe godeyi
C 683; GS6 661; K2 250;
S47 33; SSW 296


25.Spores nodulose or angular.
26

25.Spores not as above.
30


26.Cap 4-10 cm; in North America growing in low, wet, hardwood-based ecosystems.

26.Cap substantially smaller than above; in various ecosystems.
27


27.Cap .5-3 cm across.
28

27.Cap 2-5 cm across.
29


28.Stem terminating in a marginate bulb; cap 1-3.5 cm across; fairly well documented; probably widely distributed in North America.
Inocybe umbratica
GS4 397; K2 241

28.Stem not terminating in a marginate bulb; cap .5-2 cm across; poorly documented; known from New York.
Inocybe palludinella
K2 242


29.Stem hollow, not terminating in a marginate bulb; odor not recorded.
Inocybe fallax
K2 240

29.Stem not hollow, terminating in a marginate bulb; odor sweet.
Inocybe suaveolens
S78; SSW 299


30.Pleurocystidia absent; spores (9) 11-14 µ long.
Inocybe fastigiata f. subcandida
? = pale form of Inocybe rimosa
GS6 662

30.Pleurocystidia present; spore length various.
31


31.Cap tiny (4-8 mm across); growing from decaying wood.
Inocybe comatella
K2 251

31.Cap larger than above; terrestrial.
32


32.Most spores over 10 µ long.
33

32.Most spores shorter than 10 µ.
34


33.Cap densely fibrillose.
Inocybe bakeri
K2 245

33.Cap silky, or with a slightly fibrillose margin--becoming slightly fibrillose with maturity.
Inocybe serotina
K2 250


34.Cap 1.5-4 cm across.
35

34.Cap 3-6 cm across.
37


35.Pleurocystidia 54-72 µ long; widely distributed; common; well documented species.

35.Pleurocystidia under 50 µ long; ranges apparently limited to northeastern North America; not common; documentation sparse.
36


36.Stem 4-6 mm thick, equal, not hollow; buttons with a "profuse" cortina; odor not recorded; recorded from New York (possibly only by the type collection).
Inocybe sambucella
K2 252; ATK 215

36.Stem 2-4 mm thick, with a basal bulb, usually hollow; cortina not mentioned by Grund & Stuntz; odor spermatic; recorded from Nova Scotia.
Inocybe pallidicremea
GS4 399


37.Pleurocystidia under 55 µ long; stem 4-8 cm long.
Inocybe kauffmanii
= Inocybe longipes
K2 248; S78

37.Pleurocystidia longer than 55 µ; stem 2.5-6 cm long.
38


38.Pleurocystidia abundant, thick-walled.
Inocybe sindonia
photo by Irene Andersson
C 681; K1 464; K2 251
Roody, 2003

38.Pleurocystidia scattered, thin-walled.
Inocybe insinuata
K2 252



References

Abbreviations correspond to those in the key above.

[A] Arora, D. (1986). Mushrooms demystified: A comprehensive guide to the fleshy fungi. Berkeley: Ten Speed Press. 959 pp.

[ATK] Atkinson, G. F. (1918). Some new species of Inocybe. American Journal of Botany 5: 210-218.

[C] Cripps, C. L. (1997). The genus Inocybe in Montana aspen stands. Mycologia 89: 670-688.

[GS1] Grund, D. W. & Stuntz, D. E. (1968). Nova Scotian Inocybes. I. Mycologia 60: 406-425.

See index below.

[GS2] Grund, D. W. & Stuntz, D. E. (1970). Nova Scotian Inocybes. II. Mycologia 62: 925-939.

See index below.

[GS3] Grund, D. W. & Stuntz, D. E. (1975). Nova Scotian Inocybes. III. Mycologia 67: 19-31.

See index below.

[GS4] Grund, D. W. & Stuntz, D. E. (1977). Nova Scotian Inocybes. IV. Mycologia 69: 392-408.

See index below.

[GS5] Grund, D. W. & Stuntz, D. E. (1980). Nova Scotian Inocybes. V. Mycologia 72: 670-688.

See index below.

[GS6] Grund, D. W. & Stuntz, D. E. (1981). Nova Scotian Inocybes. VI. Mycologia 73: 655-674.

See index below.

[GS7] Grund, D. W. & Stuntz, D. E. (1983). Nova Scotian Inocybes. VII. Mycologia 75: 257-270.

See index below.

[GS8] Grund, D. W. & Stuntz, D. E. (1984). Nova Scotian Inocybes. VIII. Mycologia 76: 733-740.

See index below.

Hansen, L. & Knudsen, H., eds. (1992). Nordic macromycetes Vol. 2: Polyporales, Boletales, Agaricales, Russulales. Copenhagen: Nordsvamp. 474 pp.

[K1] Kauffman, C.H. (1918). The gilled mushrooms (Agaricaceae) of Michigan and the Great Lakes region, Volumes I and II. New York: Dover. 924 pp. (1971 Reprint.)

Kauffman, C. H. (1920). Studies in the genus Inocybe. The species of Inocybe in Peck's collections. Bulletin of the New York State Museum 233-234: 43-60.

[K2] Kauffman, C. H. (1924). Inocybe. North American Flora 10: 227-260.

[MK] Matheny, P. B. & Kropp, B. R. (2001). A revision of the Inocybe lanuginosa group and allied species in North America. Sydowia 53: 93-139.

Matheny, P. B., Liu, Y. J., Ammirati, J. F. & Hall, B. D. (2002). Using RPB1 sequences to improve phylogenetic inference among mushrooms (Inocybe, Agaricales). American Journal of Botany 89: 688-698.

Matheny, P. B. (2005). Improving phylogenetic inference of mushrooms with RPB1 and RPB2 nucleotide sequences (Inocybe; Agaricales). Molecular Phylogenetics and Evolution 35: 1-20.

Nishida, F. H. (1989). Key to the species of Inocybe in California. Mycotaxon 34: 191-196.

Phillips, R. (2005). Roger's Mushrooms. Retrieved from the World Wide Web: http://www.rogersmushrooms.com (see links below).

Smith, A. H. (1949). Mushrooms in their natural habitat. New York: Hafner Press. 626 pp.

[SS] Smith, A. H. & Stuntz, D. E. (1950). New or noteworthy fungi from Mt. Rainier National Park. Mycologia 42: 80-134.

[SSW] Smith, A. H., Smith, H. V. & Weber, N. S. (1979). How to know the gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 334 pp.

[S47] Stuntz, D. E. (1947). Studies in the genus Inocybe I. New and noteworthy species from Washington. Mycologia 39: 21-55.

Stuntz, D. E. (1954). Studies in the genus Inocybe II. New and noteworthy species from Michigan. Papers of the Michigan Academy of Science, Arts, and Letters 21: 163-197.

[S78] Stuntz, D. E. (1978). Interim skeleton key to some common species of Inocybe in the Pacific Northwest. Notes and species descriptions by Gibson, I. (2004). Retrieved from the Pacific Northwest Key Council Web site: http://www.svims.ca/council/Inocyb.rtf



Index to Taxa Described by Grund & Stuntz in Nova Scotian Inocybe Papers (I-VIII)

    abjecta II: 925
    abundans VIII: 737
    acreolens sp. nov. III: 19
    acuta IV: 394
    albodisca V: 670
    apiosmota sp. nov. III: 21
    aurora sp. nov. III: 24
    aurora var. inodorata var. nov. VII: 257
    brunneolipes sp. nov. II: 928
    calamistrata var. mucidiolens var. nov. II: 929
    calospora V: 672
    cervicolor VIII: 739
    chalcodozantha sp. nov. I: 408
    cincinnulata I: 409
    cryptocystis VII: 259
    decipientoides I: 411
    erythospilota sp. nov. VIII: 735
    fastigiata var. subcandida VI: 662
    fulvella V: 672
    fuscicothurnata sp. nov. III: 27
    fuscodisca II: 931
    gausapata VI: 656
    griseoscabrosa V: 673
    heterochrominea sp. nov. VII: 259
    hirsuta III: 28
    hirsuta var. maxima V: 676
    holoxantha sp. nov. VI: 667
    hystrix V: 678
    intricata var. intricata VII: 261
    intricata var. pallidistipata var. nov. VII: 261
    jacobi VIII: 738
    lacera var. heterosperma var. nov. IV: 403
    lacera f. subsquarrosa VI: 670
    lanatodisca I: 412
    lanatodisca var. phaeoderma comb. nov. III: 30
    leptophylla VII: 263
    longicystis I: 413
    maculata I: 415
    maritimoides IV: 401
    melleiconica sp. nov. I: 416
    microteroxantha sp. nov. VI: 658
    minima VIII: 733
    mixtilis V: 679
    multicoronata I: 418
    napipes II: 932
    neobrunnescens nom. nov. II: 934
    neobrunnescens var. leucothelota var. nov. IV: 395
    nemorosa comb. nov. I: 420
    nodulosa IV: 400
    oblectabilis V: 681
    obscurobadia stat. nov. IV: 407
    pallidicremea sp. nov. IV: 399
    parcecoacta sp. nov. IV: 392
    permucida sp. nov. VII: 264
    personata V: 681
    phaeoleuca I: 421
    prominens VI: 664
    rimosoides VI: 665
    rosellicaularis sp. nov. VII: 265
    scabra II: 935
    semifulva sp. nov. VI: 659
    stuntzii sp. nov. III: 25
    subdestricta I: 422
    subexilis V: 684
    submuricellata var. stenospermina var. nov. VII: 266
    subochracea II: 936
    umbratica IV: 397
    umbrina I: 423
    ventricosa VI: 671
    vinosistipitata sp. nov. VII: 269
    xanthomelas V: 686



Cite this page as:

Kuo, M. (2007, April). The genus Inocybe. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/inocybe.html