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segregate

(pl. segregates)

Terms discussed: lumper (pl. lumpers), lumping, segregated, split, splitter (pl. splitters), synonymize, synonymous


Topics:
What is segregation and synonymy?
in the professional world
in this website

     

What is segregation and synonymy?



Photo of Armillaria mellea by John Denk
Armillaria mellea
A segregate taxon is one created by dividing an existing taxon into (presumably) more precise taxa. Once upon a time, for instance, all "honey mushroom"s were considered a single, very variable species called Armillaria mellea. However, this species has since been split into several species (a dozen in North America alone). These species (Armillaria gallica, for example) are segregates from Armillaria mellea. Segregating new taxa gives you more names to learn, but it gives you a much clearer idea of what to expect from each name.

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Photo of Armillaria gallica by John Denk
Armillaria gallica
For some reason, mycologists tend to say that they're splitting off new species from the old one, but segregating new genera. Go figure.

A person who likes to split taxa is sometimes called a splitter. The opposite of a splitter is a lumper. A lumper likes to decide that two or more taxa are synonymous (that is, really the same thing) and lump them together under a single name.

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in the professional world


Modern taxonomists have done a lot of lumping and splitting of 19th century (and older) taxa, mostly splitting of genera and lumping of species. We tend to lump the older species because 19th century (and older) mycologists often named a mushroom as new just because it was unusually large, or had an unusual color for that species, or had some other unusual developmental characteristic. There was another problem, too: many tropical and asian species were named by european mycologists ( Berkeley and Hennings come to mind) who had material brought to them by expeditions. Since they were unfamiliar with these fungi in their original habitat, and had never seen the range of variation to which they were subject, if a second (or third) expedition brought them the same fungus, they often failed to recognize it and gave it a second (or third) name. 20th century mycologists have put in a lot of hours cleaning up messes like that. That a lotta lumping

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Modern mycologists have also split quite a few older "variable" species (like the honey mushroom), where people have long suspected that more than one species was being treated under a single name. In this case, modern mycologists are able to split the species because they have more sophisticated tools (primarily DNA analysis) available to differentiate the mushrooms. This sort of work gets more publicity, because people actually use the new names (and this annoys other people, generating still more publicity). By contrast, a lot of the old names that get synonymized haven't been used in a while, so no one cares; and in a lot of cases, names that probably should get synonymized aren't, because they aren't used anyway and no one wants to bother.

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The changes that most annoy the average mushroom-hunter, however, are the segregation of new genera, based on (a) the ever-increasing number of species and the need to divide them into manageable groups and (b) ever-increasing sophistication in our methods of differentiating fungi. Maybe an example will help.

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Photo of Favolus alveolaris by John Denk
Favolus alveolaris
Linnaeus used one genus (Boletus) for all mushrooms with pores. He did this even though the genus Polyporus was available, created by Micheli. Think of it: all the Boletaceae and all the Polyporales in one genus. The mind boggles. Fries helped things out somewhat by resurrecting Micheli's genus Polyporus. He furthermore divided it into three subgenera: Favolus (with large pores that resemble a honeycomb), Microporus (small pores, more or less round), and Polysticta (no real tubes; just little round impressions in the fertile surface)

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Image of Fomes fomentarius from Eugen Gramberg (1913) Pilze unserer Heimat
Fomes fomentarius
What followed is a miniature history of the creation/segregation of new genera in general. By 1850, there were six Friesian genera, mostly created on the principle of "one of these things is not like the other". There was Fomes, for all perennial polypores (most of them hard and woody).

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Image of Trametes suaveolens from Jean Louis Émile Boudier (1904 - 1909) Icones mycologicae ou iconographie des champignons de France, principalement Discomycètes
Trametes suaveolens
There was Trametes, for leathery things with fur on top. Favolus was preserved, but Hexagona was added, for things with even bigger hexagonal pores (most of them are just about the size of actual honeycombs). Polyporus and Polysticta were used as the garbage categories, for "everything else". Daedalea was already in existence (created by Persoon), but it seems to have taken quite a while for people to realize that Daedalea was somehow "like" a polypore.

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Image of Polysticta reticulatus from Christian Gottfried Daniel Nees von Esenbeck (1816 - 1817) Das System der Pilze und Schwämme
Polysticta  reticulatus
In any case, Polysticta soon fell by the wayside. As you might guess from the description above, any mature fungus that actually fits Polysticta is not really a polypore. Its two original species seem to have been resupinate polypores that were just getting started - - polypores grow their cap, and then grow their pores out from it; thus, if you catch it when the pores are just getting started, it will look like the "pores" are just shallow pits rather than true tubes. His second species is based on Nees von Esenbeck's Boletus reticulatus (Nees, an earlier author, was following Linnaeus' system, where everything with pores is a bolete), pictured here.

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Image of Polysticta molluscus from Christian Gottfried Daniel Nees von Esenbeck (1816 - 1817) Das System der Pilze und Schwämme
Polysticta  molluscus
I don't know why Fries didn't also include Nees' Boletus molluscus, shown here; but his other flagship Polysticta was clearly more of the same. In any case, several attempts were made at redefining Polysticta so that it could be distinguished consistently and productively from the other genera. Most of them developmental in nature (the entire cap grows before the pores start forming, versus the pores start growing immediately); Overholts & J. L. Lowe's (1953) Polyporaceae of the United States, Alaska, and Canada has an interesting summary of these attempts in its introduction. They all failed, however. By the early 1900s, Polysticta had been abandoned by all except a few fanatics like Lloyd, and its remaining species were all transferred to other genera.

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That's what modern taxonomy is like all over the place: sometimes you lump, sometimes you split...
     

in this website



Photo of Cortinarius obliquus by Leon Shernoff
Cortinarius obliquus
I have synonymized several species on this website when the descriptions of each species available to me were identical in microscopic features, and differed in macroscopic features only in ways that are often due to environment. These synonymies are not intended to be statements about the absolute identities of these fungi, just about the realistic possibility of identifying them given the data available, especially when that data is as confused and contradictory as that on taxa such as Cortinarius argentatus and the members of Coarsely Fibrillose Inocybe.

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Photo of Amanita SM2 var. albovaginata by John Denk
Amanita SM2 var. albovaginata
Similarly, I have also included several species not in the books. Sometimes these are things that professional mycologists are working on and just haven't published yet; sometimes they are things that no one alive seems to know about yet. It's still fairly routine to find new species of mushrooms, even quite large ones. It's hard to say whether it adds more excitment or frustration to the study of fungi.

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