DISTRIBUTION: NZ (NA,LBI).

ECOLOGY: Rare; saprobic on soil among moss and litter in broadleaved forests, June.

Pileus -15 mm, hemisphaericus dein subumbo - natocomexus, purpureus dein lilacinoroseus, glutinosus, striatus. Lamellae emarginatoadnatae, albidae. Stipes 10-50 x 1.5-3 mm, cylindricus vel subincrassatus, pileo concolor, ad basim luteus, glutinosus. Odor nullus. Sporae  5 5-6.5 x 3 -4 um, ellpsoideae. Ad terram in silvis,  Novazelandia Holotypus PDD 27228.

ETYMOLOGY: ostrinus = purple.

The present knowledge of G. ostrinus is based upon a single collection with numerous basidiomes found in the ecologically unique rainforest near the top of Mt Hauturu on Little Barrier Island. Its slender and fragile basidiomes recall G. lilacinoides (Horak) in habit and colour. However, the two closely related taxa can be distinguished in particular by their spore size and the distinctive colour changes caused both by ageing and/or leaching of the basidiomes. Another distinguishing feature is the morphology of the terminal cells in the ixocutis. In G. ostrinus the terminal cells on the gelatinised hyphae are not differentiated at the tips whereas in G. lilacinoides the terminal cells are constantly found to be subfusoid. In addition, the separation of these two similar agarics is readily accomplished by comparing the size and shape of thc spores.

TYPE: NZ: NA, LBI, near summit of Mt Hauturu, in moss forest, 12 vi 1981, Horak, PDD 27228.