Tricholomella
Tricholomella is a fungal genus in the family Lyophyllaceae. The genus is monotypic, containing the single species Tricholomella constricta, described as new to science by the Ukrainian mycologist Mariya Yakovlevna Zerova in 1979. Zerova's original publication was invalid, and it was later republished validly by Kuulo Kalamees in 1992. The fungus is found in Asia and Europe.
Taxonomy
The presence or absence of siderophilous granulation in the basidia has been a point of contention in the taxonomic placement of Tricholomella. While this characteristic would suggest attribution to genera like Lyophyllum or Calocybe, Zerova denied the presence of such granulation in Tricholomella. This character has also presented problems in other genera such as Hypsizygus and is considered by some mycologists to be an unreliable taxonomic feature.Description
Tricholomella constricta is a white, fleshy mushroom of small to medium size, typically with a cap measuring 3–6 cm in diameter. The fruiting bodies are tricholomatoid, meaning they have a general appearance similar to species in the genus Tricholoma. Young specimens have a pure white and pruinose cap that is convex to convex-campanulate. As the mushroom matures, the cap becomes convex-plane to plane, sometimes developing an obtuse umbo. The centre may become slightly brownish, yellowish or greyish with age. The cap surface is silky, shiny, smooth and dry.The gills are white, occasionally developing a pinkish tinge, and are crowded, large, and emarginate to almost free. The stipe is white, dry, and fibrillose-floccose when young. Initially, it features a narrow membranaceous ring at the apex which quickly disappears. The mature stipe becomes fibrillose, smooth, cylindric or slightly tapered at the base, and sometimes develops a rooting base. It typically measures 2–5 cm in length and 1–1.5 cm in thickness. The mushroom has a white veil which is membranaceous and quickly disappears as the fruiting body matures. The flesh is white and thick. Both the smell and taste are strongly mealy.
Microscopically, T. constricta produces a white spore print. The spores are ellipsoid to oval, distinctly echinulate, and relatively large, measuring 7–10 × 4–6 μm. They are hyaline, inamyloid, and cyanophilous. The basidia are 4-spored. Hymenial cystidia are absent. The epicutis is not cellular, the hyphae have clamp connections, and the hymenophoral trama has a regular cellular arrangement.