Danny’s DNA Discoveries – Russula
by Danny Miller
Clade Russula “crown” - Encrusted Pileal Primordial Hyphae and Yellow Russulas
Russula ‘turci’ (Woo 72)
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 any of the three normally purple species have faded to yellow, they could be confusable with the unrelated conifer species R. olivina, below. But if you look carefully at the caps of a fresh specimen (or under a microscope), there is something special about that “matte” appearance, an almost powdery look that makes this group especially beautiful, especially when dry, due to encrustations on certain cells in the cap cuticle.
Species in the EU labelled R. turci make up as many as three different species, and without a type sequence, we don't know for sure which species is the real thing, but ours most closely matches a consensus of what probably is the real one. The genetic variation found in our local species (about 5 bp differences in ITS between us and Europe) is not necessarily enough to justify considering ours a separate species. An unusual amount of genetic 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.
Russula ‘turci’ © Ben Woo, uncommon yellow form © 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.
Russula sp. 'Woo 71’ © Ben Woo
Russula ‘murrillii’ (Woo 70)
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 reportedly lacks the iodine odor that R. turci sometimes has. The caps may not be as obviously pruinose as R. turci, and the stature is usually a bit smaller.
Species in this group fluoresce in UV light (at least this one does). This is a character that should be investigated more, as some groups have fluorescing caps and/or stems, and some don't.
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, but dozens of collections I've examined show the opposite is true. I await type sequences or some official decisions being made to make sure I have our species names correct.
Russula ‘murrillii’ © Ben Woo, encrustations on the pileal primordial hyphae © Danny Miller
Yellow Russulas – encrusted hyphae or not
Russula aff postiana (Woo 69)
This often bright yellow Russula has been going by the name R. lutea (synonym R. risigallina) over here for many years. 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 our species DNA is twice as close to R. postiana as it is to R. lutea, the one collection with spore measurements better matched R. lutea. Hmm.
Although in Europe the true R. postiana can have olive or brown tones (and maybe even a hint of pink or lilac), the only documented case of our species 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 do not seem to be 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.
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 DNA evidence showing it is closer to R. postiana. (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. Russula 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.
Russula aff postiana © Ben Woo
Russula aff olivobrunnea (Woo 46)
This lookalike of R. postiana can also be bright yellow, but it is not closely related to any of our other local Russulas and does not have the encrusted pileal hyphae. The spores are dark yellow, but not quite as dark as R. aff postiana, and a little larger. It is said to grow with spruce and fir, instead of hardwoods, but the three times it was found in the Blue Mountains of Eastern Washington and Idaho, the trees were not noted (although they are largely conifer forests).
R. olivobrunnea is a wine coloured species with a very dark centre. Our yellow species is only 2bp different in ITS2 but we don't have an ITS1 sequence yet to see how many additional differences there are in ITS1. Another sister species is Russula olivina, a yellowish species with olive or brown tones.
Russula ‘olivina’ © Ben Woo
Russula aff intermedia
This is a very pale yellow capped Russula (almost white), with very dark spores notable by the fact that the gills are much brighter than the cap.
It is rare, only found once so far near Mt. Rainier (and a memory that I might have seen one 10 years ago near Leavenworth). The nearby trees were not noted, but the closely related R. intermedia is a birch species with a bright red cap that might fade to yellow in the centre. Our species is 8bp and 1 indel different in ITS.
Russula aff intermedia © Danny Miller