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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 warty or nodulose spores. The ones without the interesting cystidia represent the oldest evolutionary lineages in the family, but interestingly enough, the warty spored species are not a related group; warty spores seem to have evolved back and forth a few times in Inocybe, something I can't explain.

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


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.

Click here to download the FASTA data of all my DNA sequences

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 key to the individual genera and much more information, see Brandon's paper.

Species mentioned: Inocybe calamistrata, hirsuta, mucidiolens, maculata, lanatodisca, neobrunnescens var. leucothelota, fibrillosa, subdecurrens, dulcamara, terrigena, delecta, leucoblema, breviterincarnata, flavella, holoxantha, niveivelata, obsoleta, occidentalis, rimosa, sororia, spuria

Inocybe - nodulose spores - click to expand

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

Species mentioned:

Inocybe - smooth spores - click to expand

One giant clade of Inocybe lost their nodulose spores (they are smooth spored) but kept the metuloids. All smooth spored species seem to be monophyletic, but make the nodulose clades paraphyletic when removed. In other words, smooth spored Inocybes are "inside" Inocybe just like Leucocoprinus is "inside" Leucoagaricus. 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:


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