Lactifluus raspei

Lactifluus raspei Verbeken & De Crop

Mycobank number: MB818508

Basidiocarps small, pleurotoid, growing on a subiculum. Subiculum white to grayish white, thinly to moderately densely effused when growing on soil, densely effused on plant seedlings. Pileus 4–7 mm diam, plano-convex when young, applanate when older; young basidiocarps sometimes papillate, depressed when older; margin slightly inflexed; margin edge entire; white, with yellow tinge when old; surface velvety, covered with hairs. Stipe very small, 2–4 × 0.5–1 mm, laterally attached, cylindric, tapered towards the base, velutinous, with a white and hairy tomentum at the base, concolourous with the pileus. Lamellae narrowly adnate, about 9–12 lamellae per pileus with 1–5 lamellulae, rather distant (in proportion to its size), relatively thick, white, edges concolorous and entire. Context 0.3–0.5 mm thick in the pileus, white, no color change where bruised. Latex not abundant, white, no color change. Spore print white. Basidiospores subglobose to broadly ellipsoid, (6.8)6.9–7.8–8.8(9.0) × 5.7–6.7–7.6(8.0) μm (Q = 1.09–1.18–1.27, n = 20); ornamentation amyloid, dense, composed of interconnected warts up to 1 μm high, usually connected by lower ridges, forming a subcomplete reticulum; plage often totally amyloid. Basidia 40–45 × 10–11 μm, subcylindrical to subclavate, 4-spored. Pleuromacrocystidia abundant, 50–60 × 7–12 μm, emergent, irregularly subclavate, sometimes narrower near apex, usually thin-walled, sometimes slightly and locally thick-walled, with a dense acicular, needle-like content. Pleuropseudocystidia very abundant, 2–3 μm diam, cylindrical and very narrow, slightly tortuous, not emergent to emergent. Lamella edge mixed, with basidia, pseudocystidia, and marginal cells; marginal cells shortly cylindrical to subclavate, 10–25 × 4–8 μm; basidia distinctly smaller than the basidia at the face of the lamellae, 25–30 × 7–8 μm. Pileipellis a lampropalisade; subpellis up to 40 μm thick, consisting of globose to subglobose cells, 10–15 μm diam; suprapellis with long, hair-shaped, thick-walled, and often septate elements, 40–120 × 7–10 μm, broader at the base, becoming narrower and sometimes very acute at the apex. Subiculum composed of hyaline hyphae which are 2–7 μm wide, septate, thick-walled, walls ±1 μm wide. Clamp connections absent.

Ecology and distribution: On soil and seedlings in mixed forest with Dipterocarpus, Castanopsis, Lithocarpus, and Quercus. Thailand.

Notes: Lactifluus raspei is most closely related to Lf. bhandaryi and Lf. uyedae. Lactifluus bhandaryi differs macroscopically by its cream to orange basidiocarps in mature stage and by its unchanging latex. Microscopically, it has longer and more emergent pleuromacrocystidia (90–165 × 12–15 μm) and pileipellis hairs with rounded apices. Lactifluus uyedae differs macroscopically from Lf. raspei by its smooth surface, latex that stains the lamellae brownish after 30 min, and the absence of subiculum. Microscopically, it has longer pleuromacrocystidia (75–95(120) × 8–11 μm) that are not very emergent but arising very deep in the subhymenium.