Coprinus

© Fred Rhoades

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

Click here for my Pictorial Key to all Inky Caps

Introduction

One of the most interesting results to come out of DNA studies was way back in 1994 (yes, they were sequencing way back then) when they found out that there are two families that create mushrooms that turn to ink, only distantly related to each other. The "shaggy manes" were closely related to the cultivated Agaricus portobello and button mushrooms, and everything else was most closely related to Psathyrella (you have to admit, sometimes they look like little inky caps that just don't turn to ink). Since the first Coprinus (inky cap) named was the shaggy mane, it got to keep the name Coprinus. All the others changed their genus and their family, with Psathyrella getting a promotion to having a family named after it, the Psathyrellaceae, to hold all the others.

How could such odd behaviour evolve twice? A current theory is that when gills evolve to be too crowded together, the spores can't escape. Remember, spores of Basidiomycota are forcibly ejected from the gills, they don't just "fall off". If the gills are too close together the spore will be thrown against the neighbouring gill, which is no good. That puts pressure to "evolve or die" another spore dispersal mechanism, and dissolving into ink was a solution to getting the spores dispersed, albeit as a liquid. You can fill a fountain pen and write or draw with mushroom ink, and like squid ink, it may be edible. I don't know of any dangerously poisonous inky caps, only some that make you very sick if eaten near the same time you consume alcohol.

Did you know that there are more than a half dozen different species of shaggy mane in the PNW? Did you know that the PNW is one of the places in the world where shaggy manes have been most studied, and that almost every single one of the species I talk about below, besides the common, universal shaggy mane Coprinus comatus var comatus, have their type (and only) collection described from Washington? Fred Van de Bogart described a number of species from WA in 1976 as part of his UW PhD requirements, but he found most of them only once and we had no known photographs of any of them. Not only that, few people have ever reported finding any of them since (probably because nobody has really been looking). Most are only known from Fred's original collections, but we have sequenced many of his types, and in many cases they are indeed real, distinct genetic species. Are they rare or have they always been overlooked because nobody knows about them? So please be on the lookout for anything except the common Coprinus comatus var comatus and get good collecting data and photos so we can properly document these mushrooms.

Secotioid shaggy manes that may slightly turn to ink are Montagnea and Podaxis, genetically distinct enough to keep their own genera. Podaxis may even be more closely related to Agaricus than it is to Coprinus, which is puzzling to me.

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.

Coprinus - click to expand
All inky caps have black or nearly black spores and might have free gills (though often initially attached, they secede, or break off the stem fairly easily). Coprinus, the ones covered on this page, can be told apart from the Psathyrella relatives by having truly free gills even from birth (like Agaricus) and gills that can turn an intermediate colour of pink as they mature before they turn dark (like Agaricus). They also have very scaly (shaggy) caps that are an unusual umbrella shape, often much taller than they are wide. There is a well developed ring on the stem, and a cottony thread running through their hollow stem attached at both ends. Microscopically, sterile cystidia are only present on the gill edges and nowhere else (they have cheilocystidia but no pleurocystidia).

Coprinus cf comatus var comatus EU - This species is found worldwide. It is rather large (let's say the cap is 6-12 cm tall (before it liquifies) and the stem adds up to another 20 cm to the height. It is found in grass or disturbed urban areas. Species found on dung or in deserts, or much smaller (caps 3 cm tall) or much larger (caps 12-24 cm tall and stem up to 50 cm tall) are different species described below.
But what is it? There are 2 genetic species commonly found in Europe but we don't know which one is the real one. var. comatus #1 is found once in BC and once in OR so far. If it is not the real thing, it will need a new varietal name. var. comatus #2 is not found yet in the PNW, but it is found back east and is genetically close to var. parvus, below (4 bp and 1 indel different). For now I am assuming that the real thing is the one found here, but a European study is needed to confirm this and assign proper variety names to the two species. A 2015 European paper did note the existence of the two competing concepts (plus a third one that I now know was var. parvus, below), but did not clarify which one was the real var. comatus. We need more PNW collections to see if both species are here, or only one of them.
Coprinus comatus var. caprimammillatus WA (=C. comatus var. parvus WA) - The type sequences of these varieties differ in only one location in ITS, so they may not be distinct varieties. Variety parvus is said to be on the small end (cap 4-5 cm tall) with colourless basidia sterigmata that lack a refractile plug (whatever that means). Variety caprimammillatus has some spores with an eccentric germ pore. Interestingly, var. caprimammillatus seems to be the only species Fred collected more than once (besides the very common var. comatus). He found it a total of 15 times, including once in Montana. It is also the only species of his that somebody else has found. Since var. parvus is only known from one collection in WA in 1951 and has virtually the same ITS sequence as var. caprimammillatus, I am going to assume that it was an aberrant collection, and I am going to declare var. caprimammillatus the proper name for this taxon, since its description reflects how it is almost always found. We should get sequences of other genes besides ITS of both types to confirm that they are not genetically distinct in other gene regions. We have sequences from Alaska, Victoria BC and Oregon.
Coprinus comatus var excentricus AZ - We don't have a type sequence of this variety which was found once in AZ in 1973 and once in WA, but it has much larger spores than the others (14-18u long) and most of the spores have quite eccentric germ pores. It sounds like it is a valid variety.

Coprinus comatus #1 and C. comatus var. caprimammilatus © Jonathan Frank

Coprinus colosseus WA - This species has very large spores (17-20u long) and can also grow quite large (cap 12-24 cm tall, stem an additional 35-50 cm tall)! It was described from a dry area in dense brushy scrub in 1966, but has since been found in grass in OR and CA. It is quite genetically close to Coprinus asterophoroides, described next, a smaller desert species with similarly large spores (the type sequences differ by 3 bp in ITS). Both the OR and the CA sequence were 1 bp different than the type sequence, but still 3 bp different from the type of C. asterophoroides. Neither the OR nor the CA collection were anywhere near as tall as originally described (6" tall caps instead of up to 24" tall), but they did seem larger than the average C. comatus. Perhaps, without checking for very large spores, this species might be recognized by being, on average, bigger than C. comatus and its varieties.
Coprinus asterophoroides WA - Also with very large spores, but a small species (cap only 3 cm high and stem <12 cm tall) also from desert areas. There is said to be a star shaped universal veil patch on the cap when young. Genetically very similar to the much larger Coprinus colosseus, above, differing by 3 bp. Known only from Washington in 1974. Given that the modern collections of C. colosseus were not nearly as huge as the type collection, and the similar dry habitat, it's possible that they could be the same species. We need to study more collections.

Coprinus colosseus © Jonathan Frank

Coprinus xerophilus WA - A similar small, desert species with large spores, but instead of a star shaped patch, the universal veil remnants leave one irregular shaped patch or several smaller patches. It also has a bulbous, volvate stem base. DNA shows it is indeed a very distinct species. Known from Washington and Utah in 1957. Both of these desert species may look like Montagnea at first glance, the secotioid genus described below.

The rest of these species are fairly small, described as "miniature shaggy manes".

Coprinus umbrinus UK - This small species was reported once by Fred in WA. It was found on horse and cow dung. We need local and UK DNA to compare to see if this is indeed what Fred found.
Coprinus spadiceisporus WA - This small species is found on deer or rabbit dung in the wild. The stem apex turns black in age. We do not have DNA to confirm that it is a unique species from Coprinus roseistipitatus. They both have the same size spores (8-10u long), but this species has spores that appear translucent brown in KOH under a scope, as opposed dark purplish grey for Coprinus roseistipitatus/palmeranus.
Coprinus roseistipitatus WA - This similar deer or rabbit dung species has a pink stem apex in age, but white stem base. No clamp connections. The type sequence exactly matches the type sequence of Coprinus palmeranus in ITS. Both are known only from WA in 1975.
Coprinus palmeranus WA - The type sequence is the same as Coprinus roseistipitatus, but it was found in grass and disturbed areas. Rarely, you can find a few microscopic clamp connections in the stem only, so it seems plausible that it could be the same species, where they were just overlooked or not present in the type collection of the Coprinus roseistipitatus. However, the different ecologies (dung vs. grass) speak to the possibility that they could still be separate species. We need to study more collections.

'Coprinus' alnivorus WA and 'Coprinus' arachnoideus WA - The two species that Fred placed in section Coprinus (in the case of Coprinus alnivorus because it has a ring) that turned out to be Psathyrella relatives instead of Coprinus species, are these two. Closer inspection reveals that they do not have a stem thread like other Coprinus and they do have pleurocystidia on the gill faces, which true Coprinus do not. To his credit, he noticed they fit kind of halfway between section Coprinus and other sections, and his placement was tentative. The former is a small, pale species of Coprinopsis that was found on wood that just has a little more developed ring than the others. It is very rare, or at least always overlooked. The latter turns out to be a synonym of Coprinellus flocculosus, as the type sequence is at most 2 bp different than all the European sequences of that mushroom. They are discussed on the other inky cap page.

Montagnea and Podaxis - click to expand
Secotioid relatives of the inky caps are not genetically close enough to belong in Coprinus, which is somewhat unusual. They do deserve their own genera. Montagnea is a sister genus to Coprinus. Podaxis is closer to Agaricus and may have somewhat independently developed inkyness.

Podaxis cf pistillaris - The "desert shaggy mane" looks like a shaggy mane growing in the desert, but has a contorted spore mass instead of gills under the cap. It is surprising that it is not a sister genus to Comatus, but instead may be more closely related to Agaricus. I'm not sure what the type area is (Europe? India? ???) and we don't have local sequences, so more study is needed to determine what species of Podaxis we have here, although it seems to resemble P. pistillaris. Desert species.

Podaxis cf pistillaris © Harley Barnhart

Montagnea cf arenaria - At first deeply buried, an outer membrane ruptures to leave a sac-like volva at the base of the stem. The cap is not taller than it is wide, unlike the other species on this page, but splits into a series of spore bearing plates (not gills). I believe it is a European mushroom, but we have neither European nor local sequences to compare to see which species we have, although it seems to resemble M. arenaria. It is a desert species, as many secotioid mushrooms evolved in desert climates.

Montagnea cf arenaria © Michael Beug

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