Pi1eus 3-8 mm diam, hemispherical when young, becoming convex or plano-convex in age, disc neither depressed nor umbilicate, margin weakly plicate; surface dull, dry, minutely pruinose; at first white overall, soon becoming pale grey, finally changing to pale brown. Texture membranaceous; context very thin, white.- Lamellae broadly adnate to subdecurrent, subdistant (912) with 0-1 series of lamellulae, white; edges even, concolorous.- Stipe 5-7 x 0.5 mm, central, equal, cylindrical, often curved, tough, minutely pruinose overall, non-insititious, base with short, strigose, concolorous hairs attached to substrate; white overall or with the base becoming pale brown in age.- Odor and taste not distinctive.
Basidiospores 5.5-7.0 x 3.5-4.0(-4.5) µm, ovoid to ellipsoid, smooth, thin-walled, hyaline, inamyloid. - Basidia 18-22 x 5-6 µm, subclavate, 4-spored, unclamped.- Cheilogloeocystidia common, 40-60 x 10-14 µm, broadly fusoid to narrowly lageniform, subcapitate, thin-walled, hyaline or with yellow contents.- Pleurogloeocystidia uncommon, like cheilogloeocystidia.- Pileipellis a hymeniform layer of broadly clavate to globose, smooth, hyaline cells, 12-20 x 8-16 µm; with numerous pileogloeocystidia interspersed, 20-40 x 6-8 µm, cylindrical-subcapitate to lageniform-capitate, often with yellow contents.- Tissues inamyloid, non-gelatinous. - Caulogloeocystidia numerous, 30-45 x 7-10 µm, like cheilogloeocystidia. - Clamp connections absent.

Habit, habitat and distribution.- Solitary, rarely cespitose, in groups on rotting wood in Nothofagus-Melicytus-Weinmannia forest. New Zealand.

Pileus 3-8 mm, convexus vel planoconvexus, haud umbilicatus, subplicatus marginem versus, minute pruinosus, albidus dein pallide griseus vel pallide brunneus. Lamellae adnatae vel subdecurrentes, subdistantes, albae. Stipes 5-7 x 0.5 mm, centralis, cylindricus, minute pruinosus, haud insititius, albidus, raro pallide brunneus ad basim. Odor saporque nulli. Basidiosporae 5.5-7.0 x 3.5-4.5 µm, ovoideae vel ellipsoideae, leves, hyalinae, inamyloideae. Basidia 18-22 x 5-6 µm, 4-spora. Cheilogloeocystidia 40-60 x 10-14 µm, late fusoideae vel anguste lageniformia, subcapitata, hyalina vel pigmento luteo impleta. Pileipellis hymeniformis, ex cellulis late clavatis vel globosis, 12-20 x 8-16 µm, pileogloeocystidia capitata numerosa, 20-40 x 6-8 µm, cylindrica vel lageniformia, pigmento luteo impleta. Trama inamyloideum, haud gelatinosum. Caulocystidia 30-45 x 7-10 µm, ut cheilogloeocystidia. Fibulae nullae. Solitarius vel rariter caespitosus, ad lignum putridum Nothofagi, Melicyti vel Weinmanniae. Nova Zelandia. Horak 69-19 (Holotypus, PDD).

Gloiocephala gracilis is characterized by the following features: small, plicate, white to pale brown pilei; well-developed, subdistant lamellae; a white, pruinose, non-insititious stipe; fructification on rotting wood; relatively small basidiospores; numerous subcapitate gloeocystidia with yellowish contents on pileus, stipe and hymenophore; and the absence of clamp connections. Gloiocephala gracilis belongs in sect. Gloiocephala, subsect. Gloiocephala in Singer's (1976) classification. The new species is closely allied with G. alvaradoi Singer, an unclamped species described from Argentina. Gloiocephala alvaradoi differs, however, in forming a white pileus, fewer lamellae, longer, basidiopores (7.0-9.5 µm), much narrower pileipellis cells (3-6 µm diam versus 8-16 µm diam in G. gracilis), and sporulates on wood of Alnus and Polylepis (fide Singer, 1976).

Material examined- - NEW ZEALAND: South Island, Prov. Nelson, Murchison, near Buller Bridge, 25 I 1969, Horak 69-19 (Holotype, PDD; Isotype, SFSU, ZT).