Gliophorus europerplexus Dentinger, A. M. Ainsw. & P. F. Cannon 2013

Pileus 10–25 mm diam., hemispherical to conical or campanulate, sometimes with incurved margin, becoming plano-convex or remaining broadly conical, often umbonate, sometimes with irregular, lobed outline, margin faintly to strongly translucently striate to half-way, viscid or at least very lubricous, sometimes partially flared, at first usually pink-brown to orange-brown (brick, rusty tawny to fulvous), margin paler sometimes with orange (sienna to apricot) tints, hygrophanous, dried pilei dull orange (saffron to rust). Lamellae ventricose, mostly narrowly to broadly adnate with some slightly decurrent elements, intervenose, concolorous with pileus near pileal attachment, becoming paler towards free edge. Stipe 12–60 × 2–8 mm, cylindrical or compressed, sometimes with clavate base, hollow, sometimes flexuose, viscid but usually slightly less so than pileus, apically concolorous with pileus, paler below, sometimes basally tinted orange (apricot). Dried lamellar trama (lens) often darker than subhymenium and lamellar surfaces. Green pigments entirely absent. Without distinctive taste or smell, although one specimen [K(M)181241*] was noted to have a faint rubbery smell reminiscent of Gliophorus laetus. Spores [70, K(M)181241*, K(M)181245*, K(M)181246*] (6.5–)7.0–9.0 × (4.0–)4.5–5.5(–6.0) µm, per-basidioma mean values 7.5–8.0 × 5.0 µm, Q=1.3–1.8, mean 1.6, short-ellipsoidal to ellipsoidal, not constricted. Basidia predominantly 4-spored, clavate with attenuated base, (30–)34–57 × 5–9 µm excluding sterigmatal length (3.0–7.0 µm). Clamp connections on basidia, within lamellar trama and pileipellis usually normal, occasionally with conspicuously looped hook cells (medallion clamps). Lamellar trama subregular, compartments 20–120 × 4–21 µm. Stipitipellis and pileipellis are ixotrichoderms.

Identified from two sites in west Wales (Merionethshire and Pembrokeshire) supported by DNA sequence data. Fruiting was probably observed at the type locality by D.J. Harries on 6 August 2009 but no material was kept.

Gliophorus europerplexus is a species of agaric (gilled mushroom) in the family Hygrophoraceae. It has been given the recommended English name of butterscotch waxcap. The species has a European distribution, occurring mainly in agriculturally unimproved grassland. Threats to its habitat have resulted in the species being assessed as globally "vulnerable" on the IUCN Red List of Threatened Species.