Clitocybe harperi

Clitocybe harperi, commonly known as Harper's whitetop, is a species of mushroom in the Clitocybe genus.

Interesting characteristics and ecological roles:

Saprotrophic Nature: Clitocybe harperi is a saprotrophic mushroom, which means it plays a crucial ecological role in breaking down dead organic matter in forest ecosystems. It helps decompose leaf litter and woody debris, recycling nutrients back into the soil.

Ecological Associations: This mushroom species is often found in association with coniferous trees, including spruces, pines, and hemlocks. Its preference for such environments makes it an indicator species for certain types of forest ecosystems.

Distinctive Appearance: While Clitocybe harperi may appear unremarkable to some, its subtle beauty lies in the details of its cap and gill colors, as well as its unique growth patterns, which can be fascinating to those with a keen interest in mushroom identification.

Seasonal Fruiting: Like many mushrooms, Clitocybe harperi has a specific fruiting season, typically from September to November. Observing the seasonal patterns of mushrooms in the wild can be an interesting aspect of mycology.

Variable Amyloidity: The amyloidity (ability to stain with iodine) of its spores can vary within the same species depending on factors like age, environment, or testing conditions. This characteristic can be intriguing to mycologists studying the variability of mushroom spores.

Clitocybe harperi features:
Cap:
Size: The cap of Clitocybe harperi typically ranges from 5 to 11 centimeters in diameter.
Shape: Initially convex, becoming slightly depressed with age and often developing an umbonate (raised central bump) at the center.
Texture: The cap surface is dry and can vary from smooth to finely scaly.
Color: The central portion of the cap is pale brown to brown, while the margin is whitish to grayish. The margin is also described as having a rolled or curved appearance.

Gills:
Attachment: The gills are short and decurrent, meaning they run slightly down the stem.
Thickness: They are thin and tightly packed.
Color: When young, the gills are whitish, but as they mature, they turn brown to gray.

Stem:
Size: The stem measures 4.5 to 8 centimeters in length and 1.3 to 2.2 centimeters in width.
Shape: The stem is equal in width throughout its length and is described as full or solid.
Color: The stem color matches that of the cap, being concolorous.

Flesh:
The flesh of Clitocybe harperi is whitish to brownish in color.

Smell and Flavor:
This mushroom species is noted to have an indistinct smell.

Spore Print:
The spore print is white.

Microscopic Characteristics:

Subhymenium: The subhymenium, which is the layer just below the gill surface, can be up to 15 µm thick. It consists of branchy and arbuscular structures formed by short-branched hyphae measuring 3–3.5 µm in diameter.

Basidia: The basidia are cylindrical-clavate in shape and typically have four sterigmata, which can be up to 4 µm in length. Sometimes, only two sterigmata are present. Basidia lack carminophilic/siderophilic granulation and are weakly amyloid on the apical part. Their size ranges from (13)21-28 x 4-5 µm.

Spores: The spores of Clitocybe harperi are ellipsoid when viewed from the front and slightly ovoid to amygdaloid when viewed from the side. They are not found in tetrads or collapsed groups. Spores are smooth, weakly amyloid (staining with iodine), often cyanophilic (affinity for blue staining), and measure (4.5)5–6(7) x (2.5)3–4 µm, with an average size of 5.3 x 3.5 µm. The spore ratio (Q) is in the range of 1.40–1.65, with an average Q of 1.53.

Cheilocystids: Cheilocystids are absent.

Pleurocystids: Pleurocystids are scattered, cylindrical, and feature apical antler-like protrusions, reaching sizes of up to 26 x 8 µm.

Lamellar Frame: The lamellar frame is regular and formed of cylindrical to swollen hyphae, which measure 5–16 µm in diameter. Thromboplerous hyphae are especially frequent toward the base and edge of the gills, featuring yellow content and measuring 5–7 µm in diameter. Thromboplerous hyphae are characterized by their irregular shapes and content resembling clots.

Pileitram: The pileitram is homomorphic, formed of hyphae often running parallel. These hyphae have smooth walls, are 4–6.5 µm in diameter, and are mixed with branched and anastomosing thromboplerian hyphae. Thromboplerian hyphae have homogeneous yellowish content and measure 5–9 µm in diameter.

Pileipellis: The pileipellis is duplex: a) Trichocutis: Comprising swollen hyphae arranged radially with yellow, finely granular intracellular pigment, these hyphae are 5–12 µm in diameter. They are mixed with slender, dispersed hyphae that are attenuated at the septa and have encrusted walls, measuring 2.5–3 µm in diameter. b) Thick subpellis: The thick subpellis is formed of regular cylindrical hyphae with thin walls, measuring 3–8 µm in diameter. It is mixed with abundant thromboplerian hyphae with yellowish contents that react in Melzer's reagent (iodine-based) test.

Stipitipellis:
The stipitipellis is formed of a caulohymenium.

Loops:
Loops are absent.

Growth Mode:

Clitocybe harperi can grow either singly or gregariously (in groups).

Ecology:
Trophic Mode: This species is a saprotroph, meaning it obtains nutrients by decomposing organic matter.
Habitat: It is typically found on soil under coniferous trees such as spruces, pines, and hemlocks.

Fruiting Period:
Clitocybe harperi typically fruits from September to November.

Edibility:
This species is considered inedible, likely due to its small size and unremarkable taste.

Molecular Confirmation:
A molecular confirmation reference is provided as CMMF014712, collected from Shipshaw by Gérard Guérin, with a Genbank accession number MG321364. This reference may serve for genetic identification and comparison with other specimens of the species.

Remarks:
Clitocybe harperi can be easily identified based on its growth habit, ecological niche, and the presence of uncurled hyphae.
The amyloidity (iodine staining property) of its spores can vary within the same taxon depending on factors such as the age of the mushroom, environmental conditions, strain variation, or the specific testing protocol used for staining.

References

1. MycoMatch (MatchMaker) Mushrooms of the Pacific Northwest Version 2.4.1.
2. Alvarado, P., Moreau, P.-A., Dima, B. & Coll. (2018) Pseudoclitocybaceae fam. nov. (Agaricales, Tricholomatineae), a new arrangement at family, genus and species level. Fungal Miscellaneous.