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Danny’s DNA Discoveries – Inocybaceae of the PNW
by Danny Miller

Click here for my Pictorial Key to Inocybe s.l.


Recognized by a usually tattered appearance, sometimes called "fibre heads". I mention unusual groups of mushrooms (like Psathyrella) that have a cellular cap cuticle, composed of spherical cells that can break up in any direction. In contrast, Inocybe is the poster child for the typical kind of mushroom cap. Made up of long fibrous material, the caps will usually only split radially from the centre out to the edge of the cap. The smooth capped species are hard to recognize, but the typical Inocybe cap is dry, fibrillose or scaly, not hygrophanous and often umbonate. There is often a small bulb at the base of the stem, and the stem apex may be pruinose - these are important characters to note when trying to identify one. They are mycorrhizal, and can also be recognized by their odor, usually an unpleasant spermatic smell. They also usually have a cortinate veil like Cortinarius, and are actually very easily confused with some Telamonias, which usually lack scales on the cap, lack the spermatic odor and never have a bulb. Most Inocybes are suspected to be poisonous, containing muscarine, and due to their being ubiquitous near almost every forested area, they are responsible for many of the accidental mushroom poisonings by children and pets. Inocybe spores may take a while to mature, leaving the gills white for a long time, so it is hard to tell that they are brown spored until they are old. This is a good reason to always consider other possible spore colours unless you have proven what the spore colour is by taking a print. Very difficult to tell apart, Inocybe is one of those genera that most identifiers cannot usually get to species. Only a few species are colourful, and the rest are usually just shades of brown.

However, there are very interesting things to see under a microscope. Some Inocybes have cystidia, sterile cells on the gills, that are shaped like bowling pins with bad haircuts, called "metuloids". Some of those have very distinctive nodulose spores (with broad bumps like a jumping jack instead of the usual small or thin spines that other non-smooth spores usually have). The ones without the interesting cystidia represent the oldest evolutionary lineages in the family. Then metuloids and nodulose spores evolved in the genus Inocybe. It appears that finally, a large clade of Inocybe evolved back to smooth spores (keeping the metuloids) paraphyletic inside Inocybe, but a multi-gene study will have to confirm this. There are some smooth spored species that might have evolved their smooth spores independently from the larger group. Because they are paraphyletic (similar to how Lueocoprinus is inside Leucoagaricus) and because they may not all be in the same clade, the smooth spored Inocybe are not getting their own genus.

Inocybe metuloids © Danny Miller and nodulose spores © A and O Ceska


Ditte Bandini is one of the top experts in Europe, providing us many type sequences and other reliable sequences of European species. Our own Brandon Matheny (former PSMS educator who got his PhD at UW and is now at U Tennessee) is the undisputed North American expert on Inocybe, taking the reins from Daniel Stuntz, former UW mycologist before Joe Ammirati.

abundant common uncommon rare - colour codes match my Pictorial Key and are my opinions and probably reflect my bias of living in W WA. Rare species may be locally common in certain places at certain times.

Summary of Interesting Results
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Inosperma, Mallocybe and Pseudosperma - click to expand

The species without metuloids (and never with nodulose spores) probably represent the oldest lineages, before either of those traits evolved in the family. Although as a group these three genera are easy to separate from Inocybe with a microscope, they are more difficult to recognize individually. I think I would have preferred considering them all to be Inocybe, but then other mushrooms around the world that don't seem quite so Inocybe-like would have to be called Inocybe as well, and those people might have objected. For a more in-depth key to the individual genera and much more information, see Brandon's paper.

Species mentioned: Inocybe calamistrata, hirsuta var. maxima, mucidiolens, atrovirescens n.p., maculata, lanatodisca, fibrillosa, subdecurrens, dulcamara, terrigena, delecta, leucoblema, malenconii, breviterincarnata, flavella, holoxantha, niveivelata, obsoleta, occidentalis, bulbosissima, rimosa, sororia

Inocybe - nodulose spores - click to expand

Inocybe itself probably evolved both metuloids and nodulose spores from the ancestral genera above.

Species mentioned: Inocybe albodisca, albodiscoides, alpigenes, assimilata, californica, castanea, ceskae, chelanensis, cicatricata, curvipes, decemgibbosa, fallax, grammata, heterochrominea, pseudoteraturgus, maritimoides, bufonia, rangiferi, intricata var. pallidistipitata, jacobi, lanuginosa, leptophylla, mixtilis, napipes, nematoloma, petiginosa, phaeocystidiosa, praetervisa, prominens, radiata, ranierensis, soluta, sphagnophila, stellatospora, suaveolens, subcarpta, umbratica, variabillima, xanthomelas, nigrodisca

Inocybe - smooth spores - click to expand

At least one giant clade of Inocybe lost their nodulose spores (they are smooth spored) but kept the metuloids. We need a multi-gene study to find out how many different clades lost their nodulose spores, but it may be that most of them are in one giant clade. Chances are you're going to need a scope to identify any Inocybe, so I don't feel too bad about making you use a scope to know which section to expand (something I usually try to avoid).

Species mentioned: Inocybe geophylla, elysii, sambucella, whitei, pudica, armeniaca, insinuata, lilacina, pallidicremea, ionocephala, agglutinata, fuscodisca, virgata, fuscicothumata, obscuroides, cincinnata var. major, pyrotricha, griseolilacina, pusio, catalaunica, leiocephala, picrosma, kauffmanii, brunneolipes, semifulva, chalcodoxantha, submuricellata var. stenospermina, nitidiuscula, involuta, volvata, vaccina, laetior, cinnamomea, subdestricta, flocculosa, plurabellae, sindonia, melleiconica, oetziana, fraudens, olympiana, microlepidota n.p., griseoscabrosa, hotsoniana, glabripes, fuscidula, chondroderma, lanatopurpurea, lacera, helobia, moravica, beaucensis np, monticola, pseudodestricta, eutheloides, hemileuca, pallidipes, praecox, siskiyouensis, splendens


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