Gasterocarp 1-5 cm diam., subglobose, ellipsoid, pyriform, irregular, often lobed. Peridium whitish to ochraceous, often cyanescent on bruising, smooth, tomentose or glabrous, indehiscent, non-separable. Gleba initially pale becoming darker brown, at times violaceous on exposure, firm, loculate, consisting of minute, irregular chambers, almost invisible to naked eye. Tramal plates thin, gelatinized or not. Hyphal system monomitic, with hyaline, thinwalled or gelatinized, narrow, generative hyphae; clamp-connexions absent. Columella reduced or absent, often forming fine radial branches from the base; sterile base very reduced to absent. Spore deposit rusty brown. Spores statismosporic, orthotropic, 9-20 µm long, ellipsoid to fusoid, subhyaline to golden brown, with a slightly thickened, smooth wall forming 4-6 or more longitudinal, meridional ridges, with plane or strongly concave facets; a thin, hyaline myxosporium overlies the exosporium and sometimes becomes detached around the spore base; hilar appendix short cylindric with a terminal hilar pore, sometimes retaining sterigmal remnants. Basidia short clavate, with slender sterigmata, soon autolysing, not forming a regular hymenium. Hymenophoral trama regular, gelatinized or not. Peridiopellis a repent epicutis of thinwalled hyphae. Development angiocarpic. World-wide, uncommon, hypogeal to subepigeal. Type species: C. caespitosa Rolland.

The position of the monotypic family Chamonixiaceae within the Basidiomycota remains uncertain. It is usually stated to be allied to Gyrodontaceae (Singer) Heinem. of the Boletales, on the basis of similarity in gasterocarp pigmentation and possible mycorrhizal associations, yet differing in the constant absence of clamp-connexions. A comparison is also frequently made between Chamonixia and Gautieria Vittad. in the Cortinariales, owing to the spore type with longitudinal costae, and Dodge & Zeller (1934), Cunningham (1944), and Cribb (1958a) listed Chamonixia as a later synonym. However, the similarity is only superficial. The ridges on the Gautieria spore are formed by outgrowths of the exosporium and therefore solid, whilst the ridges of the Chamonixia spore are formed by an undulation of the entire eusporial wall and are, in a sense, hollow. Gautieria also differs in the production of a fuscous brown, rather than a rusty brown spore deposit and by the presence of clamp connexions.
Chamonixia gasterocarps are rarely encountered in most regions of the World, and although a monographic treatment of the North American species was published by Smith & Singer (1959), the species remained poorly defined. In the present paper, three species are accepted for Victoria State, with spore size and form being used as the primary character for their separation.