PILEUS: deep carrot orange to apricot, somewhat lighter at the margin in older FBs or upon drying (hygrophanous); shallowly umbillicate; (sub-)velutinous; ~12-28mm in diam., more or less circular when young to kidney bean shaped in age, umbillicate above the stipe attachment; margin fertile, very slightly incurved, undulating in age; flesh fragile to rubbery-cartilaginous, not breaking cleanly; context concolorous with darkest pileus shades but drying lighter (hygrophanous); 1mm thick at disc and tapering toward margin. LAMELLAE: very pale cream colored to very pale yellow-blonde, taking on a a distinct marigold cast upon drying/with age, up to 3mm broad near stipe, tapering slightly toward pileus margin; lamellulae in ~3 series; lamellar edge concolorous though appearing slightly frosted/encrusted under the hand lens (cheilocystidia?); attachment adnexed to minutely sinuate with slight decurrent tooth. STIPE: up to ~25mm long x ~3mm wide, slightly larger above though generally equal; eccentrically attached; with same surface ornamentation and coloration as pileus though lighter at the base; bottom-most portion of base segregated by a distinct constriction, beneath which are abundant white rhizomorphs; CONTEXT solid and concolorous with pileus but ligher upon drying (hygrophanous). Pileus, stipe, and gill edge immediately darkening in KOH, though initially exuding an orange extractable pigment, later becoming dark blue-green.
MICRO: cheilocystidia dark blue-green in KOH, abundant, crowded, some apically enlarged, others broadly clavate, finger-like or lageniform, protruding beyond hymenium; pleurocystidia not observed; basidia alternately two- or four-sterigmate; spores broadly ellipsoid to ellipsoid, small, ~1-guttulate, possibly with hilar appendage, some hyaline and some pigmented like the gill edge.
SUBSTRATE: in soil and on very rotten, partially buried wood beside the trail
HABITAT: in primary pre-montane to montane humid broadleaf tropical forest
A mostly solitary, conspicuous, seldom collected agaric, occurring exclusively in undisturbed Neotropical forests, whose ITS sequence data bear no close matches in either GenBank or UNITE, likely requiring either the erection of a new genus or a recombination significantly distant from any core Lactocollybia spp.