Truffle Genus: Gymnomyces

Gymnomyces monosporus basidiospore scale = 10 µm Gymnomyces brunnescens basidiospores

Kingdom: Fungi Phylum: Basidiomycota Order: Russulales Family: Russulaceae

Spore Characters

Surface: Ornamented with rods and spines, lines and ridges, a partial to complete reticulum, or any combination of the above; rods and spines range from 0.5-2.5 µm tall; lines and ridges are usually less than 1 µm tall.
Shape and Size: Longitudinally symmetrical, globose to ellipsoid, 7-20 x 6-16 µm (excluding ornamentation); attachment straight, prominent on many species.
Wall: 1-4 layers, up to 2 µm thick.
Color in Water: Hyaline to brown.
Melzer's Reaction: Spore ornamentation may be strongly gray to purple or black or simply black-spotted; spore walls range from nonreactive to gray or purple. One rare species of Gymnomyces has nonreactive ornamentation with only a pale purple reaction from the spore wall. In this case, in order to be assured of a purple reaction, the spore must be compared in Melzer's and KOH.
Comments: Gymnomyces and Arcangeliella cannot be distinguished at the genus level by spore characters alone; they are mostly separated on the basis of sporocarp morphology. Cystangium, Gastrolactarius, and Macowanites differ from the three genera of Gymnomyces by sporocarp morphology and by having spores that are often longitudinally asymmetric with offset attachments. Gymnomyces is related to the mushroom genus Russula.

View photos of Gymnomyces spores

Sporocarp Characters

Shape and Size: Subglobose to turbinate or irregular, 0.5-5 cm.
Peridium: Lacking to thick, smooth to felty or pubescent, when present white to orange-yellow or brown, sometimes rose to red-spotted, composed of interwoven hyphae and in many species with a turf of cystidia or hyphal tips on the surface.
Gleba: With small to prominent, rounded to labyrinthine chambers; columella lacking or present as a few, narrow, sterile veins or as a basal pad; color white to pink, orange-yellow or brown.
Odor: Not distinctive to iodine or chlorine-like.

View photos of Gymnomyces sporocarps

Name Derivation

Named by British mycologist George Edward Masee (1850-1917) and colleague Leonard Rodway (1853-1936) from Tasmania Australia (Massee, 1898) from Greek, gymno- (naked) and -myces (fungus), "naked fungus" . The type species lacked a peridium, so the gleba was exposed or "naked" (Singer and Smith, 1960).

Distribution

In forests of ectomycorrhizal conifers and hardwoods of North America, Europe, Australia, Asia, and New Zealand.
Season: Throughout the year when not limited by dry or cold weather.
Species known from North Temperate Forests: Twenty or more, including several as yet undescribed taxa.

Keys and Descriptions

Singer and Smith (1960) cover most species described from the Northern Hemisphere, but their nomenclature included most Gymnomyces spp. in Martellia. Pegler and Young (1979) and Miller (1988) describe and illustrate representative spores. Lebel and Trappe (2000) redefined the genus. Trappe et al. (2002) corrected the nomenclature and present a complete list of all Gymnomyces species known as of that date.