The unique mushroom featured in today’s edition of Fungi Friday has caused some serious taxonomic debates for years. Amparoina spinosissima is known to many as Mycena spinosissima. On the mushroom cataloging website mushroomobserver.org, one receives no results when searching for ‘Amparoina spinosissima’ but five observations appear when ‘Mycena spinosissima’ is typed. If this species was more common, I’m sure there would be a more definitive answer to these taxonomic oddities, but even so, the species is still insanely cool. After I attempt to clear up its biological classification, I will talk about an awesome adaptation the mushroom has, that will enhance its fitness well into the future. By then, we’ll probably already have another name for the peculiar forest floor inhabitant.
In 1950 this species was found growing from twigs in an Argentinean forest. It was first described as Marasmius spinosissimus, until the world renown German mycologist Rolf Singer transferred the species to Amparoinaspinosissimus in 1958. This taxonomic shift was driven by the observed inamyloid spores, but yet again, categorization of the fungus remains cloudy, as 1995 and 1999 collections reveal amyloid spores. In the 2010 paperI found, researchers found a specimen, and used Melzer’s reagent to see if the spores were amyloid or inamyloid. Like Rolf Singer initial observation, the researchers identified inamyloid spores, so they stuck with the name Amparoina spinosissima.
In amyloid spores, the Melzer’s reagent reacts with starch like polysaccharides on the spore’s surface, and changes the structure’s color. Inamyloid spores don’t have this polysaccharide covering their spores so the reaction doesn’t happen. This is a common tool used to help distinguish different species, though, for this scenario, has only caused confusion. This discrepancy would be clarified if this species was easily found, and had a wide distribution, but unfortunately for us, the mushroom is tiny and pretty rare. There can be but two things going on here. What most likely is going on is multiple non-related, phenotypically similar species are popping up around the world. The other, less likely possibility, is that this starch-like polysaccharide covering its spores is actually a plastic trait.
Although the genus is constantly being shifted around, the one thing ALL mycologists CAN agree on is its species name-spinosissima. This name will stand the test of time, because, well look at it! There are tiny spines covering is cap and stem. Spines and tendrils are found throughout the fungal kingdom. Some spines help perturb mycophagy, making it harder for small invertebrates to take a bite. This species produces these spines to enhance its dispersal. But that’s what spores are for, right? Spores are a fantastic method of dispersal, and I’m not knocking these little packets of potential fungal propagules, but the fact holds that their success isn’t guaranteed. Actually, most airborne spores don’t germinate, that’s some why mushrooms produce billions of spores each day.
These spines break off and actually function as a fungal propagule. Once broken off, they germinate into a clone of the mushroom they just broke off from. This is the fitness enhancing advantage. Spores are haploid, only containing half of the parent’s genes, so if and when they germinate, they need to meet up with another compatible haploid hyphae. Once they do, they can sexually recombine their genes, and form another mushroom. Amparoina spinosissima can readily form new mushrooms with its already genetically recombined fungal tissue flaking off into the forest floor below.
The forest floor never ceases to amaze me. This method skips the need for haploid hyphae to combine with another haploid network. The mushroom still produces spores, so sexual recombination still occurs, but it can easily clone itself to pump even more of these spores into the air. This trait is fitness enhancing and is also used by glow in the dark fungi as well. When enough specimens are collected around the world, and people take more of an interest in the species, genetic techniques will elucidate taxonomic discrepancies. I only wish the species grew in my area. I guess I’ll just have to add it to my bucket list.