Lactifluus armeniacus De Crop & Verbeken.
MycoBank number: MB 815137; Facesoffungi number: FoF02056
Pileus 69–72 mm diam., planoconvex with central depression to slightly infundibuliform; margin sometimes slightly striate, sometimes concentrically wrinkled; edge rather irregular, sometimes crenulate or locally undulate; surface chamois leather-like, locally wrinkled but smooth in the centre, pruinose, bright orange(as 5B5/6, but more yellow), unicolourous. Lamellae adnate with decurrent tooth to subdecurrent, distant (2 L + 1 l / cm – 4 L + 3 l / cm), bright orange to yellow (4A3 to 4/5A4), very broad, rather thick and brittle, slightly intervenose; edge entire and concolourous. Stipe 27–28 × 11–18 mm, cylindrical to slightly tapering downwards, sometimes curved, centrally attached to pileus; surface very soft, pruinose and finely striate, concolourous with pileus (bright orange 5B5/6 with a more yellowish tinge). Context solid and quite firm, white, unchanging; taste sweet, mild; smell not distinctive. Latex abundant, white, unchanging; taste sweet. (Fig. 2)
Basidiospores broadly ellipsoid, sometimes subglobose, sometimes ellipsoid, 6.4–7.7–9 × 5.1–6.2–6.7 μm (n = 20, Q = 1.11–1.24–1.41); ornamentation amyloid, forming an almost complete reticulum, composed of very low warts connected by fine ridges, up to 0.2μm high; plage inamyloid. Basidia 4-spored, sometimes 2-spored, 59–71 × 8–9μm, cylindric to subclavate, with refringent to slightly thickened walls; content guttate to granular. Pleurolamprocystidia abundant, slightly emergent up to 17μm, cylindrical, septate, 50–80 × 4–8 μm, with slightly thickened walls (<1 μm). Pleuropseudocystidia very scarce, 7–9μm, cylindrical, mostly collapsed at apex; content granular. Lamellae-edge sterile; completely composed of cheilolamprocystidia which are 41–45 × 4–7 μm, cylindrical, septate, thick-walled. Hymenophoral trama cellular, with abundant lactifers and sphaerocytes. Pileipellis a lampropalisade; elements of the suprapellis 28–64 × 3–5 μm, cylindrical, obtuse, thick-walled; subpellis 132–174 μm thick, sphaerical cells 9–22μm diam., with thickened wall. Stipitipellis hymeniderm; elements of the suprapellis 15–26 × 5–11 μm, cylindrical to clavate, sometimes with strong congophilous content, thick-walled. (Fig. 3)
Material examined: THAILAND, Chiang Mai Province, Mae Taeng district, Baan Tapa (22 km marker along road 1095), N19°7′45″ E98°46′1″, alt. 766.8 m, on soil in mixed forest, with Dipterocarpus sp., Castanopsis sp., Lithocarpus sp. and Quercus sp., 31 July 2014, E. De Crop 14–501 (holotype in MFLU, isotype in GENT).
Fig. 1 Maximum likelihood tree of Lactifluus subg. Lactariopsis and L. subg. Rugati, based on ITS-LSU sequence data. Maximum likelihood bootstrap values >70 are shown. New taxa are in blue and species for which obtained sequences are based on type material have names in bold.
Fig. 2 a Lactifluus armeniacus (holotype) b Lactifluus ramipilosus (holotype).