[ Ascomycota > Pezizales > Pezizaceae > Rugosporella . . . ]

Rugosporella atrovinosa

by Michael Kuo, 1 November 2024

I've collected this cup fungus a few times over the years, and it's pretty distinctive. It appears in hardwood forests in the Midwest, growing directly from the ground. It's a small to medium-sized cup with a bald upper surface, and its colors are somber, ranging from dark brown to purplish brown to black. Under the microscope, it features ascus tips that turn blue in Melzer's Reagent, slightly swollen paraphyses, and distinctive ellipsoid spores with very prominent ornamentation—a series of ridges and nodule-like warts up to 2 µm high (enlarge the bottom illustration).

Since I usually find Rugosporella atrovinosa in the spring, comparison to Phylloscypha phyllogena (AKA Peziza badioconfusa) is warranted; could my collections merely represent old specimens of the latter species, beginning to blacken? But the specimens in my collections are not particularly old, and plenty of black, but immature, specimens have been among them. Also, the nearly fusiform, delicately ornamented spores of badioconfusa are not even remotely similar. In summer and fall Legaliana badia (formerly Peziza badia) is also similar, but the ornamentation on its spores is a fine, low-ridged reticulum.

Thanks to Django Grootmyers and Ethan Crenson for help identifying this fungus.

Peziza atrovinosa is a synonym.

Description:

Ecology: Probably mycorrhizal; growing gregariously in bare soil in hardwood forests; spring; distribution uncertain. The illustrated and described collections are from Illinois and Ohio.

Fruiting Body: Cup-shaped when young, remaining so in maturity, or becoming saucer-shaped; 1–3 (rarely 5) cm across; upper surface bald, dark brown to black, becoming a little wrinkled centrally, the margin blackening; undersurface finely fuzzy (with a hand lens) or nearly bald, dark brown to black; stem absent; attached to the substrate at a central location; flesh brown, brittle, not exuding juice when squeezed.

Odor: Not distinctive.

Spore Print: White (enlarge the 4th illustration to see spore print caused by the scanner's light).

Microscopic Features: Spores 12–20 x 6–12 µm including ornamentation; more or less ellipsoid; at first smooth, but soon developing nodules and ridges up to 2.5 µm or more high, often arranged longitudinally, creating the impression of striae or a partial reticulum; developing large polar caps up to 4 µm wide and 3 µm high; in KOH hyaline to yellowish and 1- or 2-guttulate; in Melzer's yellowish to golden, with some ornamentation amyloid. Asci 8-spored; with amyloid tips. Paraphyses hardly exceeding the asci; 4–8 µm wide at the apex; apices subclavate to clavate; smooth; hyaline to yellow-brown (en masse) in KOH. Excipular surface of textura globulosa-angularis, appearing nearly hymeniform; terminal elements 20–40+ µm long, globose to ellipsoid or pyriform, smooth, hyaline to brownish in KOH.

REFERENCES: (M. C. Cooke, 1875) D. H. Pfister, R. Healy & K. L. LoBuglio, 2024. (Seaver, 1928; Pfister, 1978; Norman & Egger, 1996; Sánchez-Jácome & Guzmán-Dávalos, 2005; Raymundo et al., 2012; Medel et al., 2013; Pfister et al., 2024.) Herb. Kuo 05300401, 06241001, 10071203, 06071301, 06082401.

This site contains no information about the edibility or toxicity of mushrooms.

Asci in MLZ, developing spores

Paraphyses

Spores

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2024, November). Rugosporella atrovinosa. Retrieved from the MushroomExpert.Com Web site: December://www.mushroomexpert.com/rugosporella_atrovinosa.html.