''Mycena fuscoaurantiaca'' 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 reported as a new species in 2007, the diminutive mushroom is only found in Kanagawa, Japan, where it grows on dead fallen twigs in lowland forests dominated by hornbeam carpinus and Chinese evergreen oak trees. The mushroom has a brownish-orange conical cap that has grooves extending to the center, and reaches up to in diameter. Its slender

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 colored similarly to the cap, and long—up to tall. Microscopic characteristics include the weakly amyloid spores (turning blue 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 smooth, swollen cheilocystidia and pleurocystidia ( cystidia on the gill edges and faces, respectively) with long rounded tips, the diverticulate hyphae of the

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 ...

, and the absence of clamp connections.

Taxonomy, naming, and classification

The mushroom was first collected by Japanese mycologist Haruki Takahashi in 1999 and, along with seven other ''Mycena'' species, identified 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 derived from 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 ...

words ''fusco-'' (meaning "dark") and ''aurantiaca'' ("orange-yellow"), and refers to the color of the fruit bodies. Its Japanese name is ''Taisha-ashinagatake'' タイシャアシナガタケ(代赭足長茸). Takahashi suggests that the species is best classified in the section ''Fragilipedes'', as defined by Dutch ''Mycena'' specialist

Rudolph Arnold Maas Geesteranus Rudolf Arnold Maas Geesteranus (20 January 1911 in The Hague – May 18, 2003 in Oegstgeest), was a Dutch mycologist Mycology is the branch of biology concerned with the study of fungus, fungi, including their genetics, genetic and biochemistry ...

. Within the section, the North American species '' M. subfusca'' appears to be closely related to ''M. fuscoaurantiaca''. ''M. subfusca'' may be distinguished by its spindle- to broadly club-shaped cheilocystidia without a narrow neck, club-shaped to irregularly shaped caulocystidia, and lack of pleurocystidia.

Description

The cap, which reaches in diameter, is initially conical to convex to bell-shaped, but becomes flattened in age. It is radially grooved almost to the center, and somewhat hygrophanous (changing color as it loses or absorbs moisture). The cap surface is dry, minutely

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 ...

initially (that is, appearing as if covered with a fine white powder), but soon becomes smooth. The cap is brown to brownish-orange when young, with a somewhat darker center, and fades to paler toward the margin with age. The flesh is white, and up to 0.5 mm thick. It does not have any distinctive taste or odor. The

is long by thick, cylindrical, centrally attached to the cap, slender, hollow, and dry. Its color is orange to brownish-orange, and it is initially pruinose, but later becomes smooth. The base of the stem is covered with coarse, stiff white hairs. The gills are adnexed (narrowly attached to the stem), and distantly spaced, with between 16 and 18 gills reaching the stem. The gills are up to 1.8 mm broad, thin, and pale brownish. The gill edges are pruinose, and the same color as the gill face.

Microscopic characteristics

The basidiospores are

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 9–10.5 by 6–7

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. They are smooth, thin-walled, colorless, and weakly amyloid. The basidia (spore-bearing cells) are 19–30 by 7–9 µm, club-shaped, and two-spored. The cheilocystidia ( cystidia on the gill edge) are thin-walled, smooth, 25–47 by 3–20 µm, abundant, spindle-shaped with a prolonged thickened tip, smooth, and colorless or pale vinaceous. The pleurocystidia (cystidia on the gill face) are 27–75 by 5–20 µm, scattered, and similar in shape and color to the cheilocystidia. The hymenophoral tissue (tissue of the

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 structure) is made of thin-walled hyphae that are 10–22 µm wide, cylindrical, often somewhat inflated, smooth, colorless, and

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 when stained with Melzer's reagent). The

is made of parallel, bent-over hyphae that are 2–7 µm wide, and cylindrical. These hyphae are smooth or covered with scattered, warty or finger-like thin-walled brownish diverticulae. The layer of hyphae beneath the cap cuticle is arranged in a parallel manner,

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

(translucent), and dextrinoid, containing short and inflated cells that measure up to 34 µm wide. The cuticle of the stem is made of parallel, bent-over hyphae that are 2–4 µm wide, cylindrical, smooth, brownish, and thin-walled. The flesh of the stem is composed of longitudinally running, cylindrical hyphae that are 8–20 µm wide, smooth, colorless, and dextrinoid. The

strigose Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

(stiff or bristly) hairs at the base of the stem are 2–6 µm wide, and arise directly from the stem cuticle. They are bent-over or erect, cylindrical, with rounded tips, sometimes flexuous (winding from side to side), smooth, colorless, and thin-walled. Clamp connections are absent in all tissues of this species.

Habitat and distribution

''Mycena fuscoaurantiaca'' is known only from Kanagawa, Japan. It is found growing solitary to scattered on dead fallen twigs in lowland forests dominated by 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 Chinese evergreen oak (''

Quercus myrsinifolia ''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 ...

''). Fruit bodies appear in November.

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=Q5681413 fuscoaurantiaca Fungi of Asia Fungi described in 2007 Flora of Japan