Holotype (PDD 27061); Isotype (Herb. HK. ZT 68/382): 'Track to St. Arnaud Range., Lake Rotoiti, Prov. Nelson, N.Z.; leg. Horak, 5 V.1968'.

Gastrocarp 15-30 x 8-20 mm, globose or ovoid when young, becoming depressed at the centre, margin of the peridium appressed to the stipe but in the end partially exposing the gleba, at the centre red-brown or chestnut brown, towards the margin lilac or violaceous (like Phlegmacium dibaphum), colours fading on over-mature carpophores, glutinous, smooth, margin without veil remnants. Gleba loculate, chambers irregularly arranged, up to 2 mm diam., rust brown, exposed in aged specimens but always covered with white or lilac fibrils. Stipe 10-20 x 7-10 µm, cylindric, attenuated towards the apex (columella), and extending above into the cuticular layer of the peridium, white or lilac, longitudinally covered with white or lilac fibrils, glutinous and membranaceous ring or volva present, initially ring or volva continuous with the gelatinous cuticle of the peridium. Context white, not gelatinised. Odor unpleasant, like acetylene. Taste mild. Chemical reactions on peridium: KOH and HCl- negative.
Spores 11-14 x 7-8.5 µm, ovoid or elliptic-oblong, mostly axially symmetric, verrucose, warts coarser towards the apex, ferruginous, germ pore absent. Basidia 30-40 x 8 µm, 4-spored. Cystidia absent. Epicutis consisting of a thick layer of strongly gelatinised, hyaline hyphae (2-6 µm diam.), with a thin-walled membrane, clamp connections numerous.

On ground under Nothofagus cliffortioides, N. menziesii and N. fusca. New Zealand.

Gastrocarpio 15-30 x 8-20 mm ex hemisphaerico ovoideo, demum centro depresso, marginem versus involuto, violaceo-lilacino, apicaliter castaneo, glutinoso, glabro. Gleba lacunosa, ferruginea fibrillis albido-violaceis obtecta. Stipite (columella) 10-20 x 7-10 mm, percurrente, cylindraceo, apicaliter attenuato, ex albido lilacino, annulo violaceo vel volva concolori, glutinosa membranaceaque instructo, Odore ingrato. Spore nullo. Sporis 11-14 x 7-8.5 µm, ovoideis vel ellipticis, verrucosis, ferrugineis. Basidiis 4-sporigeris. Cystidiis nullis. Epicute ex hyphis gelatinosis cutem formatibus, septis fibuligeris. Ad terram in silvis nothofagineis. Novazelandia.

Th. violaceovolvatum Hk. is suggestive of three other species of Thaxterogaster (Th. glutinopallens Hk., Th. lubricum Moser, Th. gliocyclum Hk.) occurring in the Nothofagus forests of South America. The distinct red-brown and lilac colours, however, serve to separate clearly the New Zealand species from their relatives in Patagonia. With respect to the microscopical characters all four species also show close relationships.

Holotypus (PDD 27061): 'St. Arnaud Range., Lake Rotoiti, N.Z.; leg Horak, 5.V.1968'.