Lactifluus ramipilosus Verbeken & De Crop, sp. nov.
MycoBank number: MB 815138, Facesoffungi number: FoF 02057, Figs. 1, and 2
Etymology – with branched (rami-) hairs (-pilosus), referring to the striking hairs in the pileipellis structure.
Holotypus – MFLU E. De Crop 14–503
Diagnosis – A medium-sized, warm yellowish orange species which is microscopically characterized by the very lowly and indistinctly ornamented spores, the absence of true cystidia and ramified thick-walled hairs in the pileipellis structure.

Pileus 55 mm diam., convex to planoconvex with undeep depression in the center; surface soft, chamois-leather like and pruinose, almost smooth but slightly irregular, yellowish orange (5A3 – 4A4); margin entire, straight to slightly reflexed. Stipe 25 × 17 mm, strongly tapering downwards; surface pale yellow (4A2), slightly paler towards the lamellae, very finely fibrillose. Lamellae broadly adnate to decurrent, up to 4 mm broad, medium thick, brittle, yellow (4A3). Context whitish yellow. Latex not observed.

Spores 5.6 – 7.2 – 8.9(9.1) × 5.5 – 6.2 – 7.2(7.3) μm, Q = 1.03 – 1.16 – 1.32, broadly ellipsoid, sometimes subglobose; ornamentation amyloid but very low and weakly developed composed of low and irregular warts that are often connected by very fine ridges forming a partial reticulum; plage mostly not amyloid, but sometimes with a very weak central amyloid spot. Basidia 4 – spored, with some rare 2 – spored basidia present, 45 – 55 × 8 – 10 μm, subcylindrical to subclavate, with guttate contents. True cystidia absent. Pleuropseudocystidia abundant, not emergent to slightly but distinctly abundant, 6 – 8 μm diam., cylindric but often swollen at the apex, with rounded apex, with needle-like to granular content. Hymenophoral trama mixed with some hyphae present but especially abundant sphaerocytes of up to 25 μm diam., with abundant lactifers. Subhymenium cellular. Lamellar edge sterile; marginal cells 15 – 28 × 6 – 8 μm, subclavate to irregular, mostly hyaline, sometimes with refringent walls, sometimes with slightly needle-like content. Pileipellis lamprotrichoderm-like, composed of a layer of hyphae with 3 – 5 μm diam., which are mainly horizontally arranged and often terminating in remarkable thick-walled hairs which are pericline to oblique; hairs thick-walled, 35 – 125 × 3 – 5 μm, often branched, sometimes septate, sometimes tapering near paex, sometimes with rounded apex.

Material examined – THAILAND, Chiang Mai Province, Mae Taeng district, Baan Tapa (22 km marker along road 1095), N19°8′0″ E98°46′15″, alt. 829.6 m, on soil in mixed forest, with Dipterocarpus sp., Castanopsis sp., Lithocarpus sp. and Quercus sp., 31 July 2014, E. De Crop 14–503 (holotype in MFLU, isotype in GENT)

Fig. 1 a Lactifluus armeniacus (holotype) b Lactifluus ramipilosus (holotype).

Fig. 2 Lactifluus ramipilosus (holotype) a Section through pileipellis b Marginal cells c Basidiospores d Basidia e Pleuropseudocystidia f Terminal elements of the pileipellis. Scale bars: a – f = 10 μm.