Pluteus atromarginatus

Description

Pluteus atromarginatus is a dark-brown mushroom with a slightly raised cap that turns grayish-brown. The cap has dark streaks, and the gills are white to gray-brown with darker edges. It is a type of mushroom that decomposes wood and has pink spores and free gills. It prefers to grow on conifer wood and is relatively large in size.

While this mushroom is considered safe to eat, its rarity means it shouldn't be collected for consumption. Although it's not commonly harvested for eating, it's important to note that some similar-looking Entoloma mushrooms, which are often toxic, also have pink spores. You can differentiate between them by examining their gills; Pluteus mushrooms have free gills attached to the stem. Additionally, considering their habitat and spore shape can help in telling them apart.

Common names: Blackedge Shield, Black-edged Pluteus, German (Schwarzschneidiger Dachpilz).

Mushroom Identification

1. Cap

   The cap measures 2.36 to 4.33 inches (6 to 11 cm) in diameter and has an obtuse-conic shape, which later expands to become plano-convex or flat with or without a small raised center (umbo). Initially, the margin is curved inward, then it curves downward to become level, occasionally displaying slight waviness. The cap's surface is a blackish-brown to dark-brown color at the center (disc), sometimes exhibiting a satin-like sheen when young. Towards the edges, it appears lighter brown and is covered with dark radial fibrils, which can be somewhat fibrous in texture. The inner context of the cap is whitish, but turns greyish-black beneath the outer layer. It remains consistent in color when cut, is soft, and relatively thin, reaching a thickness of up to 0.39 inches (1 cm). The odor is mild, and the taste ranges from mild to slightly resembling radish.

2. Gills

   The gills are free, closely spaced, and can reach up to 0.79 inches (2 cm) in width. In their early stages, they are whitish, but as they mature, they adopt a dingy-pink hue. The gill edges are even and have a distinct border, showing a white to gray-brown coloration. There can be up to five series of smaller gills (lamellulae) between the main gills.

3. Stem

   The stem measures 1.97 to 4.72 inches (5 to 12 cm) in length and 0.39 to 1.18 inches (1 to 3 cm) in thickness, having a cylindrical shape and being solid in structure. It has a fleshy-fibrous texture and remains uniform in width or slightly widens at its base. The surface of the stem is covered with closely pressed grey-brown fibrils, set against a pale background. There is no visible veil present.

4. Spore Print

   The spore print is pinkish-tan in color.

5. Spores

   The spores have dimensions of 5.5-8.0 x 4.0-5.0 µm and display a broadly elliptical to oblong-elliptical shape when viewed from the front. When seen from the side, they are similar in shape but slightly asymmetrical, with one side being straight and the other curved. The spore surface is smooth and thin-walled, lacking a prominent appendage at the hilar region. The pleurocystidia, which are specialized cells found on the gill faces, have a fusoid-ventricose shape with horned tips. The cheilocystidia, also specialized cells on the gill edges, are thin-walled and club-shaped.

6. Habitat

   This mushroom species is typically found growing alone or scattered on conifer stumps, logs, wood chips, and piles of sawdust. It's quite common in Europe and North America. Its fruiting season spans from fall to mid-winter.

Look-Alikes

1. Pluteus cervinus

   Displays a sleek, lighter brown or fawn cap and does not possess the dark border on its gills.

2. Pluteus atrofibrillosus

   Exhibits a high degree of resemblance, albeit its current documented occurrence is limited to the Great Smoky Mountains National Park. Its fibrils and scales display a "more loosely arranged" pattern according to Justo et al. (2014). Additionally, its spores are slightly diminutive, and its pleurocystidia feature only two hooks.

History

In 1925, German-born American mycologist Rolf Singer provided the initial description of this distinct woodland mushroom. He granted it the scientific name Pluteus cervinus var. atromarginatus. Elevating its status to that of a species, French mycologist Robert Kuhner (1903 - 1996) designated it as Pluteus atromarginatus in 1935.

Derived from Latin, the genus name Pluteus literally conveys the notion of a protective fence or screen - akin to a shield. The specific epithet atromarginatus signifies 'possessing a black edge or margin,' alluding to the darkened rim of the gills.

Synonyms and Varieties

• Pluteus umbrosus ss. Bresadola (1892), Fungi tridentini, novi vel nondum delineati, 2(8-10), p. 11, tab. 116

• Pluteus cervinus var. nigrofloccosus R. Schulz (1913) [1912], Verhandlungen des botanischen vereins der provinz Brandenburg, 54, p. 102

• Pluteus cervinus var. atromarginatus Singer (1925), Zeitschrift für pilzkunde, 4, p. 40 (nom. inval.)

• Pluteus cervinus subsp.* atromarginatus Konrad (1927), Bulletin de la Société mycologique de France, 43(2), p. 148

• Pluteus tricuspidatus Velenovský (1939), Novitates mycologicae, p. 143

• Pluteus nigrofloccosus (R. Schulz) J. Favre (1948), Beiträge zur kryptogamenflora der Schweiz, 10(3), p. 104

Video

Photo copyright:

All photos were taken by the Ultimate Mushroom team and can be used for your own purposes under the Attribution-ShareAlike 4.0 International license.