Melanogaster dubious (Melanogaster ambiguus) photo and description

Melanogaster ambiguus

  • Department: Basidiomycota (Basidiomycetes)
  • Subdivision: Agaricomycotina (Agaricomycetes)
  • Class: Agaricomycetes (Agaricomycetes)
  • Subclass: Agaricomycetidae (Agaricomycetes)
  • Order: Boletales
  • Family: Paxillaceae (Piggies)
  • Genus: Melanogaster (Melanogaster)
  • Species: Melanogaster ambiguus (Melanogaster dubious)

Synonyms :

  • Octaviania ambigua
  • Argylium liquaminosum
  • Melanogaster klotzschii

Melanogaster dubious - Melanogaster ambiguus


The fruit body is gasteromycete, that is, it is completely closed until the spores are fully ripe. In such mushrooms, not a cap, a leg, a hymenophore are isolated, but a gasterocarp (fruit body), peridium (outer shell), and gleba (fruiting part).

Gasterocarp 1-3 centimeters in diameter, rarely up to 4 cm. Shape from spherical to ellipsoidal, can be regular or with irregular swellings, usually not divided into segments or lobes, with a soft rubbery texture when fresh. Attached by thin, basal, brown, branching mycelium cords.

The peridium is dull, velvety, at first grayish-brown or cinnamon-brown, with age it becomes yellowish-olive, with dark brown “bruises” spots, blackish-brown at old age, covered with a small whitish coating. In young specimens, it is smooth, then cracks, the cracks are deep, a naked white tram is visible in them. In section, the peridium is dark, brownish.

Gleb is initially white, whitish, whitish-yellowish in color with bluish-black chambers; chambers up to 1.5 mm in diameter, more or less regularly located, larger towards the center and base, not labyrinthoid, empty, gelatinized with mucous contents. With age, with the maturation of the spores, the gleb darkens, becomes reddish-brownish, black with whitish veins.

Smell : in young mushrooms it is perceived as sweetish, fruity, then becomes unpleasant, resembling rotting onions or rubber. An English-language source (British truffles. A revision of British hypogeous fungi) compares the smell of an adult dubious Melanogaster with the smell of Scleroderma citrinum, which, according to descriptions, resembles either the smell of raw potatoes or truffles. Finally, mature specimens have a strong and fetid odor.

Taste : young mushrooms have spicy, pleasant

Spore powder : black, slimy.

Under the microscope

Tram plates are white, very rarely pale yellowish, thin, 30-100 microns thick, tightly woven, hyaline, thin-walled hyphae, 2-8 microns in diameter, not gelatinized, with clamping joints; there are few interhyphalic spaces.

Spores 14-20 x 8-10.5 (-12) μm, initially ovoid and hyaline, soon turning into a fusiform or rhomboid shape, usually with a subacute apex, translucent, with a thickened wall from olive to dark brown (1-1, 3) μm), smooth.

Basidia 45-55 x 6-9 microns, elongated brown, 2 or 4 (-6) spore, often sclerotized.

Season and distribution

It grows on soil, on litter, under a layer of fallen leaves, and can be significantly submerged in the soil. Recorded in deciduous forests with a predominance of oak and hornbeam. Fruiting from May to October throughout the temperate zone.


There is no consensus here. Some sources indicate Melanogaster as dubious as an unambiguously inedible species, some believe that the mushroom can be eaten as long as it is young enough (until the gleb, the inner part, has darkened).

No data on toxicity could be found.

The author of this post adheres to the principle of "not sure - do not try", so we will carefully classify this species as an inedible mushroom.

Photo: Andrey.