Pileus 4-10 mm diam., gelatinous texture, pure white, downy, dry, radially grooved following the outline of the lamellae, margin slightly incurved, drying ochraceous to sepia, depending on age. Lamellae white, thick and fold-like, well-spaced, 1-2 series, 5-6 reaching the stipe in small basidiomes, 8-10 in larger ones, sparsely furcate to intervenose at a lower level. Stipe 8-15 x 2 mm, more or less central, white at apex shading through yellow brown and sepia to black at the base, dry, even in diameter, cystidiate, insititious, tough, stipes often remaining attached to the substratum when the rest of the basidiome has disappeared. Taste and smell unknown. Spore print unknown.
Spores 10-13 x 6-9 (11.9 x 7) µm, Q=1.7, ellipsoid, lacrymoid, sometimes humped on abaxial side in lateral view, hyaline, smooth, thin-walled, inamyloid, not dextrinoid, acyanophilic, with a distinct apiculus with a terminal, dark scar. Basidia 30-35 x 11-13 µm broadly clavate, clamped at the base, 2-, 3-,.or 4-spored, sterigmata short and fat, -3 µm long. Pleurocystidia absent. Cheilocystidia 30-40 x 6-11 µm, in the form of cystidioles, cylindrical to lageniform, sometimes nodulose at the apex, thin-walled, infrequent. Trama of sub-gelatinous, more or less parallel, narrow hyphae 3-4 µm diam. Subhymenium of filamentous, slightly coralloid hyphae. Context of narrow (2 µm.diam.) gelatinised, interwoven hyphae. Pileipellis of repent hyphae with well developed rameales to asterostromelloid structure, with short diverticulations 1 µm diam. Stipitipellis of narrow (-3 µm), brown, repent hyphae with short, hyaline, thin-walled, simple or shortly diverticulate projections. Trama of lamellae and stipe not dextrinoid.

Habitat : On old dead leaves of New Zealand flax (Phormium tenax), growing in damp swampy areas.

Pileus 4-10 mm. diam., convexus, albus purus, gelatinosus, lanuginosus, aridus, sulcatus radialiter secundum imaginem lamellarum, margine parum incurvata, ochraceus vel sepiaceus pro aetate ubi aridus. Lamellae albae, velut plicatae, inter se bene distantes, in parvis basidiomatibus 5-6 ad stipitem pervenientes, in maioribus 8-10, in 1-2 seriebus, parsim furcatae vel intervenosae inferius. Stipes 8-15 x 2 mm, plus minusve centraliter iacens, umbrinus, aridus, cystidiatus, diametro aequali, valde adfixus ad substratum, saepe manens ubi basidioma reliqua evanescit. Odor et sapor ignoti. Sporarum imago inota. Sporae 10-13 x 6-9 (11.9 x 7) µm, Q = 1.7, ellipsoideae, lacrimiformes, interdum excrescentes in latere abaxiali aspectu, hyalinae, laeves, parietibus tenuibus, inamyloideae, nec dextrinoideae nec cyanophilae, apiculo manifesto cum nigro cicatrice terminali. Basidia 30-35 x 11-13 µm, late clavata, ad basim fibulata, di- tri- vel tetrasporata, sterigmata parva et obesa, -3 µm longa. Pleurocystidia desunt. Cheilocystidia 30-40 x 6-11 µm, cystidiolis similia, cylindrica vel lageniformia, nonnumquam nodulosa ad apicem, parietibus tenuibus, frequentia. Trama ex hyphis angustis, subgelatinosis, plus minusve parallelis, 3-4 µm diam. Subhymenium ex hyphis frlamentosis, parum coralloideis. Contextus ex hyphis angustis (2 µm), gelatinosis et intertextis. Pileipellis ex hyphis repentibus structurae bene effectae rameales vel asterostromelloideae, cum brevibus diverticulationibus 1 µm diam. Stipitipellis ex hyphis repentibus,- angustis (-3 µm), brunneis, cum prominentiis brevibus, hyalinis, simplicibus vel diverticulatis. Trama lamellarum stipisque non dextrinoidea. In foliis veteribus et mortuis Phormii tenacis, quod in regionibus umidis et paludosis crescit. Nova-Zelandia. HOLOTYPUS PDD 60264.

M. bonii bears a strong resemblance to M. trabutii var.trabutii but differs in the rather smaller size of the basidiome, the shallow, distant, thick, fold-like lamellae, mainly in 1 series, smaller spores, more strongly developed rameales structure in the pileipellis, and shorter protuberances on the stipitipellis.

Material : NEW ZEALAND : SOUTH IS.: Buller: on coast near Greymouth, R.Petersen, B.Segedin, 14 v 1990, PDD 60264 (HOLOTYPUS, icon).