Here is a quote from the college textbook "FUNDAMENTALS OF THE FUNGI" 4rth ed 1996 - Landecker, concerning research with A. Mellea.
Sympatic speciation involves the origin of species as a result of ecological, behavioral, or genetic barriers that arise within a single population. The barriers prevent gene flow between the populations, resulting eventually in the divergence of sympatic species. These species are unable to exchange genes even though they occupy a common habitat.
This is the case for the honey fungus Armillaria Mellea, which was classified as a single species. Mating experiments with isolates from North America and Europe revealed that a group of morphologically similar but biologically distinct species was designated as Armillaria Mellea --------
In a dikaryotic mushroom like the cubensis, the spores germinate in monokaryotic form, with the genes being incomplete. To complete the gene set, the hyphae from the spores have to mate, and then it can produce fruitbodies. So if two monokaryon hyphaes are paired in vitro in the lab, and no mating of the hyphae (no clamp connections - no exchange of genes) is observed - then the two monokaryons are a different specie or spore race. If the hyphae from two spores connect and join (clamp connection), this is evidence that they are of the same specie, spore race or race strain. Lab work on this is very detailed and complex because in the cubensis, only one in four hyphae (spores) are compatabile, so many monokaryons must be tried (one in sixteen chance for mating). And add to that the reality that only a small percentage of cubensis spores actually germinate.
When a spore sample of a given mushroom is germinated, the mycelium differentiates into types with different growing characterstics. These are the strains, that come from the spores. The strains can be seen in the fruitings themselves. For example, a cake with PF shrooms will have specimens growing next to each other or clumped on different areas of the cake that have a different look. The colors, the cap shape, speed of growth and even propensity towards bluing is varied. There can be even sterile strains in which the gills do not develope spores. These sterile strains are sometimes selected by growers because of the "cleaness" of shrooms growing without sporulating. A strain is selected by cloning, which is done by operating on the shroom, excising a tiny fragment of flesh and transplanting the fragment into a culture medium. The mycelium that grows from the fragment is a clone of the mushroom (identical genes) and when transplanted into growing medium, it will grow into a mushroom genetically identical to the parent.
The diverse spore races that PF sells are not strains. They are very different from each other and always grow that way. Each one is identifiable from each other with distinct characteristics. Because of this, there needs to be an update on the taxonomy of psilocybe cubensis. In Biology, organisms are identified as genus and specie. In psilocybe cubensis, the genus is Psilocybe and the specie is cubensis. But what about the different cubensis races? They fit like this:
race (complete genotype)
race strain (individual)
Also, - spore atrophy sets in. When a fruitbody is cloned and then continually reproduced that way, the spore system is bypassed which eventually makes the whole system go dead. Even if the mushroom continues to sporulate, the spores become weakly germinatible and unfruitfull. The senescent spores can even become inert with no germination - a dead end. So one can not "develope" a strain, but only select it out. Strains apparantly can not be "improved". They are what they are and stay that way.
The idea of hybridizing mushrooms has been jangled around for years. And apparantly, from the research and discoveries concerning the Armillaria Mellea mushroom, it is now scientifically proven that the idea of hybridizing different mushroom races or species is a myth.
The so called "hybridizing of fungi" is more like mating two selected strains. That would be possible, but then the result would still be the same specie and race and possibly a new strain, which is kind of absurd when strains are apparantly infinite. It would seem very possible that "strain hybrids" can occur. That isn't a HYBRID according to the definition (Websters New World Dictionary definition). But of course, when the spore print is taken, it is back to the full genotype spore race - with the strain or strain hybrid lost.
The research with A. Mellea has revealed the existance of these spore races which are unable to mate. The Mycologists describe this as "morphologically similar but biologically distinct species", or that these races are actually different species. This makes the taxonomy of the shrooms impossible and unworkable. But the idea of dividing the specie into spore races makes total sense. Instead of creating myriads of new specie names to designate these new spore races, the races just need to be specified in the taxonomy. For instance - Psilocybe Cubensis Equador - Psilocybe Cubensis Fanaticus - Psilocybe Cubensis Treasure coast ect. And in the case of the A. Mellea races, one can have: A. Mellea California - A. Mellea Europa or A. Mellea Japanensis ect.
In summary, this new knowledge about the unmatability of isolates of N. American and European honey mushrooms (Armillaria Mellea) shows that the theoretical hybridizing of A. Mellea is impossible. And when the clear differentiation displayed by the various races of available P. Cubensis is added to the mix, the hybrid myth is exposed.