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Danny’s DNA Discoveries – Russula
by Danny Miller
Clade Russula “crown” - Encrusted Pileal Primordial Hyphae and Yellow Russulas
This is the most common of the three local species, a European species found under various conifers that sometimes has an odor of iodine in the base of the crushed stem. The caps are most often dark purple, but may occasionally have some red tones or even have faded to yellow-brown. If you look carefully at the caps, there is something special about that “matte” appearance, an almost powdery look that makes this group especially beautiful, especially when dry. The genetic variation found in our local species (2-5 bp differences in ITS2) is not necessarily enough to justify considering ours a separate species. An unusual amount of variation in this species and R. murrillii has been found, possibly indicating that some kind of evolutionary pressure is currently causing speciation. Perhaps we are witnessing the formation of new species, and eventually, they will sort themselves out into distinct clades with further distance between them.
R. ‘turci’ © Ben Woo
Russula sp. Woo 71
This very closely related species cannot yet be told apart from R. turci. It was found 3 times in WA near Glacier Peak with fir, Doug fir, hemlock and cedar nearby. Twice it was deep purple like R. turci, but once it had red tones like R. murrillii more often does, below.
R. sp. Woo 71’ © Ben Woo
In 1913, Burlingham described this mushroom collected by W. Murrill in Corvallis, OR under conifers. She didn’t directly compare it to R. turci, but others soon did, and recognized it as a related but separate species. This species is more often reddish-purple than R. turci is (but might also be deep purple or yellow-brown), and lacks the iodine odor. The caps may not be as obviously pruinose as R. turci, and the stature is usually a bit smaller. I don’t have type sequences of either species, but many sequences of specimens from the type areas of both species are consistent with each other so there is a consensus of what represent these species. However, the descriptions of this species and R. turci seem somewhat switched with each other which I can’t quite explain. The description for R. turci says it’s often wine coloured and the description for R. murrillii is supposedly almost always pure violet. I await type sequences or some official decisions being made to make sure I have our species names correct.
R. ‘murrillii’ © Ben Woo
Yellow Russulas – encrusted hyphae or not
Russula aff postiana
This often bright yellow Russula has been going by the name R. lutea (synonym R. risigallina) over here for many years. This is another case of there being two similar European Russulas, in this case R. lutea (risigallina) and R. postiana, with mycologists deciding that our bright yellow Russula was probably R. lutea, but getting that wrong. Ours is closer to the European species R. postiana, not lutea. (A similar thing happened as described on previous pages with R. pallescens vs. R. farinipes, with R. vinososordida vs. R. decolorans, with R. cerolens vs. Russulas sororia and pectinata and also with R. sapinea vs R. puellaris). Ours may not be the same species, though. Ben's sequences of ITS2 showed 1-3 differences, not necessarily enough to justify a new species, but more recent sequences of ITS1 have shown that there are an additional 3-4 differences in ITS1.
It’s not always yellow, and specimens with other colours have been called R. chamaeleontina, for its chameleon-like properties, but that species is now assumed to be the same as R. lutea. Although R. postiana can have olive or brown tones (and maybe even a hint of pink or lilac), the only documented case of it being in the PNW is being bright yellow in Seattle under Madrone, although it’s famous for its spruce habitat in Europe. Like the R. turci group, R. postiana is in the clade with encrusted primordial hyphae, but not to the same extent, because although you can find them under a microscope, they are not sufficient in this species to make the cap matte or pruinose, it’s still relatively shiny. The spores are especially dark yellow, almost orange, possibly the darkest colour of any of our Russulas.
R. aff postiana © Ben Woo
Russula ‘olivina’ (olivobrunnea)
This lookalike of R. postiana can also be bright yellow, but it is unrelated and does not have the encrusted pileal hyphae. It is said to grow with spruce and fir, but when it was found here three times in the blue mountains of eastern Washington and Idaho, the trees were not noted. Like R. postiana, it can be greenish olive or brownish, but it has always been somewhat yellowish when found here so far. The spores are dark yellow, but not quite as dark as R. postiana, and a little larger. Our sequences are only 2 different in ITS2 than R. olivobrunnea, described from Europe in 1994, so I feel comfortable saying they are probably the same. They are 4 different from the European R. olivina (and R. olivina and R. olivobrunnea are 3 different and one indel from each other) so it is not clear if all three are the same species or not. If so, R. olivina is the oldest name, and that would be the proper name of our species. If not, then R. olivobrunnea is probably the proper name of our species. Without enough evidence yet to separate our species from R. olivina, we are assuming for now that our species is R. olivina, and that R. olivobrunnea is not a distinct species either.
R. ‘olivina’ © Ben Woo
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