''Mycena mustea'' is a species of

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

in the family

Mycenaceae The Mycenaceae are a family of fungi in the order Agaricales. According to the ''Dictionary of the Fungi'' (10th edition, 2008), the family contains 10 genera and 705 species. This is one of several families that were separated from the Tricholom ...

. First described as a new species in 2007, the fungus is known only from Kanagawa, Japan, where it grows on dead fallen twigs in lowland forests. The mushroom's dull violet to grayish-violet cap, initially covered with a fine whitish powder, becomes smooth as it matures, and eventually reaches a diameter of up to . The

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

is slender, up to long, and is covered with stiff white hairs at the base. Underneath the cap are distantly spaced pale brownish gills that are narrowly attached to the stem. Microscopic characteristics of the mushroom include the weakly amyloid spores (turning bluish to black when

stained A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials app ...

with Melzer's reagent), the club-shaped cheilocystidia ( cystidia on the gill edge) featuring one or more short knob-like protuberances, the absence of pleurocystidia (cystidia on the gill face), the diverticulate

cap cuticle The pileipellis is the uppermost layer of hyphae in the pileus of a fungal fruit body. It covers the trama, the fleshy tissue of the fruit body. The pileipellis is more or less synonymous with the cuticle, but the cuticle generally describes th ...

hyphae, and the absence of clamp connections.

Taxonomy, naming, and classification

The species was first collected in Japan by Hiraku Takahashi in 1999, and reported as a new species in a 2007 publication. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

is the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''mustea'', meaning "fresh". The Japanese name is ''Sumire-ashinagatake''. The infrageneric

classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

of the fungus is unclear, and depends on what

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

characters are deemed most important. According to Takahashi, the mushroom's violet

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

, the inamyloid (not staining when treated with Melzer's reagent) hymenophoral tissue (

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some ...

-bearing tissue), and the smooth hyphae of the outer layer of stem suggest a placement in the section ''Adonideae'' (Fr.) Quel., as defined by the Dutch ''Mycena'' specialist Maas Geesteranus. However, if greater taxonomic emphasis is placed on the weakly amyloid basidiospores, it would be more appropriate in the section ''Fragilipedes'' (Fr.) Quél.

Description

The cap is conical to convex to bell-shaped, occasionally with a low and broad umbo, and reaches in diameter. When moist, it is partly translucent, and grooves corresponding to the position of the gills under the cap can be seen. The surface is somewhat hygrophanous—it changes color as it loses or absorbs moisture. The surface is initially

pruinose Pruinescence , or pruinosity, is a "frosted" or dusty-looking coating on top of a surface. It may also be called a pruina (plural: ''pruinae''), from the Latin word for hoarfrost. The adjectival form is pruinose . Entomology In insects, a "blo ...

—covered with what appears to be a fine white powder (remnants of the universal veil that covered the immature fruit body)—but this soon sloughs off, leaving it smooth. The cap surface is a dull violet color when young, then becomes somewhat paler near the margin. The flesh is up to 0.5 mm thick, white, and lacks any distinctive odor and taste. The slender

is long by thick, cylindrical, centrally attached to the cap, and hollow. Its surface is dry, dull violet to grayish-violet over the entire length. Like the cap surface, it is initially entirely pruinose, but becomes smooth in maturity. The base of the stem is covered with sharp, straight, and stiff white hairs. The gills are narrowly attached to the stem, and distantly spaced, with between 15 and 19 gills reaching the stem. The gills are up to 1.2 mm broad, thin, and pale brownish. The gill edges are pruinose, and the same color as the gill faces.

Microscopic characteristics

The

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s are roughly

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

and measure 11–12 by 6–7 µm. They are smooth, colorless, inamyloid to weakly amyloid, and thin-walled. The basidia (spore-bearing cells) are 28–37 by 8–10 µm, club-shaped, and mostly four-spored. The cheilocystidia ( cystidia on the gill edge) are club-shaped, abundant, and measure 30–45 by 8–11 µm. They form a sterile gill edge. Near their tips they have one or more short knob-like excrescences (outgrowths) that are colorless, and thin-walled. ''M. mustea'' does not have cystidia on the gill face (pleurocystidia). The hymenophoral tissue is made of hyphae that are 5–16 µm wide, cylindrical (often somewhat inflated) with thin walls, smooth, colorless, and inamyloid. The

is made of parallel, bent-over hyphae that are 2–6 µm wide, cylindrical, and covered with scattered, warty or finger-like hyaline (translucent) thin-walled diverticulae. The layer of hyphae under the cap cuticle are parallel, hyaline or pale violet,

dextrinoid In mycology a tissue or feature is said to be amyloid if it has a positive amyloid reaction when subjected to a crude chemical test using iodine as an ingredient of either Melzer's reagent or Lugol's solution, producing a blue to blue-black staini ...

(turning reddish to reddish-brown in Melzer's reagent), and contain short and inflated cells that are up to 25 µm wide. The stem cuticle is made of parallel, bent-over thin-walled hyphae that are 2–6 µm wide, cylindrical, smooth, and hyaline or pale violet. The stem tissue is made of longitudinally running, cylindrical hyphae that are 8–15 µm wide, smooth, colorless, and dextrinoid. Clamp connections are absent in all tissues.

Similar species

''Mycena mustea'' is similar to the North American species '' M. umbrinovinosa'', which is distinguished by having a vinaceous-brown to purplish-black cap, irregularly shaped cheilocystidia that are covered at their tips with long, flexuous excrescences, and clamp connections. ''Mycena mustea'' is also similar to the European species '' M. urania'', which differs in its blackish-violet cap, broadly club-shaped cheilocystidia covered with numerous, evenly spaced warts, and clamp connections. ''Mycena mustea'' also resembles the Japanese '' M. fonticola'', a species described concurrently with ''M. mustea''. Unlike that of ''M. fonticola'', the cap of ''M. mustea'' typically becomes pale grayish-purple when mature; the cheilocystidia have several short finger-like excrescences at their tips; and the stem cuticle is made up of smooth hyphae. In contrast, the cap of ''M. fonticola'' becomes dark violet-brown when mature; there are no excrescences on the cheilocystidia; and the hyphae of the stem cuticle are sparsely covered with diverticulae that resemble warts or fingers.

Habitat and distribution

''Mycena mustea'' is known only from Kanagawa, Japan. The mushroom is found growing solitary to scattered on dead fallen twigs in lowland forests dominated by the hornbeam carpinus (''

Carpinus tschonoskii Hornbeams are hardwood trees in the flowering plant genus ''Carpinus'' in the birch family Betulaceae. The 30–40 species occur across much of the temperateness, temperate regions of the Northern Hemisphere. Origin of names The common English n ...

'') and the Chinese evergreen oak (''

Quercus myrsinaefolia ''Quercus myrsinifolia'' is an Asian species of tree in the ring-cupped oaks subgenus of the family Fagaceae. It has several common names, including bamboo-leaf oak, Chinese evergreen oak, and Chinese ring-cupped oak. Its Chinese name is ; piny ...

'').

References

External links

The Agaricales in Southwestern Islands of Japan
Images of the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen {{Taxonbar, from=Q2837246 mustea Fungi of Asia Fungi described in 2007