Russula parapallens Bazzicalupo, D. Miller & Buyck.
Index Fungorum number: IF553818 Facesoffungi number: FoF 03651
Etymology: refers to the sometimes pale colour of the cap.
Holotype: BW791 (WTU)
Pileus 2–10 cm diameter, plano-convex, not becoming infundibuliform with age, shortly striate at margin; surface smooth, patchy mixture of paler and darker shades of pinkish, tan, brownish wine red. Lamellae adnate, equal or with few lamellulae, bifurcations few or absent, normally spaced (ca 1 L/mm) and narrow in width, white to pale cream (of Woo specimens, ~50% recorded as ‘white’, ~50% as ‘cream’); edge even, concolourous. Stipe mostly longer than the cap diameter, slender, cylindrical, firm, white or sometimes with a pinkish blush. Context white, unchanging with age or on injury, reacting tan to FeSO4. Odor fruity. Taste variable (noted as hot or mild in both gills and flesh). Spore print very pale (of Woo specimens, 90% Crawshay A, ~10% Crawshay B–C). Spores broadly ellipsoid, (6.1–)7.32–7.35–7.39(–8.8) × (4.9–)6.12–6.15–6.18(–7.7) µm, Q = 1.19–1.2–1.25(–1.4); ornamentation reticulate, composed of interconnected amyloid, conical warts, (0.2–)0.67–0.68–0.69(–1.3) µm high; suprahilar spot present as a strongly amyloid patch. Basidia (28.5–)36.5–41–45.5(–49) × (8–)9–10–11(–13) µm, 4-spored, stout and slightly clavate. Lamellar trama mainly composed of sphaerocytes, intermixed with cystidioid hyphae. Hymenial cystidia 45–60(–65) × 6–7 µm, broadly clavate to fusiform, thin–walled, SV+, turning dark purple in sulfovanillin: (~25% specimens had a grey reaction). Pileipellis not sharply delimited from the underlying context of filamentous hyphae and sphaerocytes; suprapellis composed of loosely arranged hyphae with cylindrical terminal cells having obtuse tips. Pileocystidia so long that their length was hard to determine (i.e. the first septum proximal to their tip was often difficult to find), up to 9 µm thick; contents refringent. Acidoresistant incrustations absent. Clamp connections absent in all parts.
Habitat and distribution: host association unknown, but recorded with species including Picea sitchensis, Pseudotsuga menziesii, Tsuga heterophylla, and Pinus contorta. Only known from the Pacific Northwest (USA: Alaska, Oregon, Washington; Canada: British Columbia).
Examined material: U.S.A., Oregon, Lincoln City, East Devils Lake Park, 123.997778˚W, 44.966667˚N, 8 m alt., 13 Nov 1998, B. Woo BW791, F-038394 (WTU, holotype), GenBank ITS2: KX813453; Washington, Denny Creek Camp, 121.4425˚W, 47.412778˚N, 680 m alt., 07 Oct 1997, B. Woo BW712, F-039290 (WTU), GenBank ITS2: KX813398; ibidem, La Push, Mora Campground, 124.606944˚W, 47.918056˚N, 10 m alt., 28 Oct 1994, B. Woo BW581, F-038864 (WTU), GenBank ITS2: KX813309; ibidem, Sloan Creek Camp, 121.287778˚W, 48.0575˚N, 630 m alt., 08 Sep 1996, B. Woo BW629, F-039202 (WTU), GenBank ITS2: KX813343; ibidem, Sol Duc Campground, 123.857778˚W, 47.966944˚N, 510 m alt., 11 Oct 1993, B. Woo BW558, F-038823 (WTU), GenBank ITS2: KX813292; ibidem, Spirit Lake, 03 Oct 1976, B. Woo BW107, F-039383 (WTU), GenBank ITS2: KX812964.
Notes: Russula parapallens corresponds to Clade 3 in our phylogeny and to Woo sp. 32 in Bazzicalupo et al. (in press). The phylogenetic placement of R. parapallens within subgenus Russula was unsupported and its closest relatives were unresolved. Although without support, the closest distinct species in the phylogeny, R. helodes, is considered rare in Europe and characteristic of sphagnum peat bogs with birch and spruce (Sarnari 1998-2005). The closest SH found in UNITE was R. luteotacta with a 94% match (UNITE SH DOI: https://plutof.ut.ee/#/datacite/10.15156/BIO/SH284902.07FU). Russula luteotacta is ecologically very different, as it associates mostly with Quercus, Carpinus, and Castanea (Sarnari 1998–2005). Other species that appeared genetically related when looking at BLAST results included species of subsection Citrinae sensu Romagnesi (but not R. solaris Ferdinandsen & Winge), as well as some of the paler acrid-tasting west coast Russulas such as R. cremoricolor.
As of March 2017, in UNITE and in PlutoF, no SH matched this taxon’s ITS2. However, identical sequences were recorded from Canada (March 2017): Port Renfrew, Vancouver Island BC (UDB031531), Capilano Regional Park, Vancouver BC (KX579783); USA: Delta Junction, Alaska (EU222979), Bonanza Creek, Alaska (KF617596).