Russula pseudopelargonia Bazzicalupo, D. Miller & Buyck.
Index Fungorum number: IF553820; Facesoffungi number: FoF 03653
Etymology: from its prior confusion with R. pelargonia.
Holotype: BW603 (WTU, sub nr F-038653)
Pileus up to 7.5(10.5) cm in diameter, plano-convex to gently depressed in the centre, often uneven, with irregularly-wavy, striate margin; surface deep red to vinaceous red or brownish red, usually darker in the centre, sometimes pinkish toward margin, often irregularly mottled with yellow splotches or discolouring toward the margin with age, when young often with the extreme margin white, peeling up to mid-radius, strongly viscid to glutinous when wet. Lamellae adnate, cream-coloured (of Woo specimens, ~75 recorded as ‘cream’, ~25% as ‘white’), normally spaced (ca 1 L/mm), equal or with a few, sometimes very short lamellulae, and occasional bifurcations; gill edge concolourous, even. Stipe most often shorter than the cap diameter, subcylindrical or more frequently widening toward the base, white but often with a pinkish flush in the lower half, not bruising or with some yellowish brown stains at the base. Context white, unchanging, turning grey-pink to tan with FeSO4. Odor fruity or more frequently, clearly reminiscent of Pelargonium (geranium). Taste medium to very hot in gills and flesh. Spore print cream (of Woo specimens, ~25% Crawshay A; ~75% Crawshay B–C). Spores broadly ellipsoid, (5.9–)7.8–7.85–7.9(–9.8) × (4.8–)6.27–6.31–6.35(–7.9) µm, Q = (1.1–)1.24–1.25–1.27(–1.4), ornamented with amyloid, relatively high, conical warts, (0.2–)0.66–0.68–0.69(–1.4) µm, with rare interconnections; suprahilar spot present as a strongly amyloid patch. Basidia (33–)38–43.5–49(–53.5) × (7–)9–10.5–12(–13) µm, 4-spored, stout and clavate with slightly swollen top. Lamellar trama composed mainly of sphaerocytes, intermixed with cystidioid hyphae. Hymenial cystidia 60–70 × 7–8 µm, clavate, SV+ (of specimens, ~50% grey/~50% dark purple). Pileipellis not sharply delimited from the underlying context of filamentous hyphae and sphaerocytes. Suprapellis composed of loosely arranged, branching and slender hyphal terminations. Pileocystidia sometimes so long that it is hard to determine their length (i.e. find the first septum from their tip); when measurable with terminal cells ~35–40 µm long, up to 7.5 µm in width and with obtuse tips; contents refringent. Cystidioid hyphae containing refractory contents also very abundant in subpellis and trama. Acidoresistant incrustations absent. Clamp connections absent in all parts.
Habitat and distribution: consistently associated with Pseudotsuga menziesii, or Tsuga heterophylla, often intermixed with other trees; only known from Washington west of the Cascades and southern BC.
Examined material: U.S.A., Washington, Denny Creek Camp, 121.441667˚W, 47.412778˚N, 680 m alt., 24 Oct 1993, B. Woo BW562, F-038819 (WTU), GenBank ITS2: KX813295; 11 Oct 1996, B. Woo BW643, F-039024 (WTU), GenBank ITS2: KX813349; 13 Sep 1995, B. Woo BW603, F-038653 (WTU, holotype), GenBank ITS2: KX813324; ibidem, Olympia, Priest Point Park, 122.8961˚W, 47.06972˚N, 30 m alt., 31 Oct 1997, B. Woo BW747, F-038935 (WTU), GenBank ITS2: KX813422; 02 Nov 1998, B. Woo BW779, F-038903 (WTU), GenBank ITS2: KX813442; B. Woo BW784, F-038906 (WTU), GenBank ITS2: KX813446; 03 Nov 2000, B. Woo BW888, F-039282 (WTU), GenBank ITS2: KX813529.
Notes: Russula pseudopelargonia corresponds to Clade 5 in our phylogeny, to Woo sp. 36 in Bazzicalupo et al. (in press) and to UNITE SH DOI: https://plutof.ut.ee/#/datacite/10.15156/BIO/SH297365.07FU. In the phylogeny R. pseudopelargonia was placed as a well-supported sister to the European R. sardonia, the type species of subsection Sardoninae. Aside from R. sardonia’s fruity odour and very acrid taste (Marxmüller et al. 2014), the species lacks strong morphological similarity to R. pseudopelargonia and as a strict associate of Pinus, it contrasts in host preference.
In the Pacific Northwest, the Pelargonium scent of the carpophore possibly led to previous records of this species as ‘R. pelargonia Niolle’. Russula pelargonia lies phylogenetically in the unrelated subsect. Violaceinae (Miller and Buyck 2002). Russula pseudopelargonia could also be confused with many colour forms of R. salishensis but the more consistently hot taste of its flesh would sometimes help to distinguish it.
Distribution of ITS sequences identical to R. pseudopelargonia, including environmental samples, confirmed its restricted distribution to the Pacific Northwest [Canada: Port Renfrew, BC (UDB031534), BC (HQ604842)]. Except for these identical sequences, no other sequences in public databases were 97% or more identical to R. pseudopelargonia (as of March 2017).