Miller OK, Brace RL, Evenson V. 2005. A new subspecies of Mycenastrum corium from Colorado. Mycologia 97: 530-533.

Mycenastrum corium ssp. ferrugineum O.K. Mill, R. Brace & V. Evenson ssp. nov.

Fructificatio 5.5–7.5 cm lata, quum inexpansa ovalis vel subdepressa, sub maturitate in radios 6–9 obtusos vel acutos findens, quum plene aperta usque ad 8–10 cm lata, ovalis vel subdepressa, 3.5–4.5 cm alta. Exoperidium tenax (1–2 mm crassum) glabrum exasperatum aurantiaco-bubalinum vel colore hebeti-albescenti. Gleba firma, glomus glebale laeve distincte rubiginosorubrum vel rufidulo-aurantiacum formans. Columnae parvae contortae e materia glebali compositae visibiles, protrudentes vel erecto-digitiformes. Basis sterilis nulla.

Capillitium e cellulis arcte circinatis crassitunicatis compositum, 6–10 μm diametro, processibus spiniformibus plerumque 2–5 μm diametro, aliquibus partibus terminali-bus ramulos apicales contortos formantibus. Partes capillitii pigmento valde aurantiaco incrustatae. Sporae globosae vel paene subglobosae, 9.0–12.6 × 9.0–12.6 μm (Q = 1.01: 1.0–1.1, n = 31) ornamenta includentes, verrucis obtuso-acutis erectis 1.2–2.0(–3.2) μm ad basem reticulo infirmo ornatae, hyalinae, parietibus in aqua flavis, in 3% KOH valde flavis praeditae.

Holotypus in prato aprico in communitate graminea lectus, Jefferson County, Colorado, 14 Mar 1998. Leg. R-L D. & R.D. Brace (DBG 19432 Holotype, CO).

Fruiting body 5.5–7.5 cm broad slightly depressed when unexpanded, at maturity splitting into 6–9 blunt to pointed rays expanding to 8–10 cm wide when fully open, oval to slightly depressed, 3.5–4.5 cm high. Exoperidium tough (1–2 mm thick) glabrous, becoming roughened pale orange-buff (Met 7A B2) to dull whitish, peeling in places to reveal a dull brown endoperidium (Met 7 D5). Gleba firm, forming a smooth distinctive rusty red to reddish orange (Met 9D 6–7, Met 8E 7–8, Met 8C 6–7 to Met 7E 6) glebal ball which does not break down readily and may become free from the peridium. When gently broken apart the gleba is powdery but does not stick to fingers. Small delicate columns of gleba are visible which protrude or stand erect finger-like. In cross section the gleba has irregular chambers caused by the finger-like projections or glebal columns. There is no sterile base, and the gleba fills the fruiting body.

Capillitium of densely coiled thick-walled cells 6–10 μm diam with spine-like projections, usually 2–5 μm diam, which are most abundant over the tapered ends. Some terminal elements have contorted end branches. Cross walls are not present, the capillitial elements are encrusted with strong orange to orangered pigments in water mount (FIG. 2). The pigments leach out when treated with 3% KOH (FIG. 1).

Spores globose or slightly subglobose, 9.0–12.6 × 9.0–12.6 μm (Q = 1.01: 1.0–1.1, n = 31) including the ornamentation composed of bluntly pointed erect warts 1.2–2.0(–3.2) μm with a weak reticulum at the base, hyaline with yellow walls in water, deeply yellow in 3% KOH.

Habit, habitat and distribution.—

Terrestrial, commonly gregarious and often clustered in open meadows flooded in the spring and bordered by cottonwoods, willows and elms in a grass community. Occurring singly, several or in an arc. Fruiting in February and March and known only from a meadow in the Wheat Ridge Greenbelt west of Kipling Street, Jefferson County, Colorado (39°46′49″N, 105°06 ′87″W, elev. 5398 ft). 

Material examined.—

UNTIED STATES: Colorado; Jefferson County, Coll. R.L. & R.D. Brace 2/28/98 DBG 19431; 3/14/1998 DBG 19432, holotype; 2/25/2001 DBG 21356.

 Observations.—

The distinct rusty red to orange-red (Met 8E 7–8 to Met 9A-B 6–7) glebal pigmentation (FIG. 4) of this new subspecies differs from all collections and reports of Mycenastrum corium in which the gleba is olive-brown at first (FIG. 3) and umber to purple-brown in age (Met 5D 5–7 to 6E 6–7). The finger-like columns described above are typical of the variety corium but usually not described as such. The glebal columns found in M. corium ssp. ferrugineumare more delicate than those in M. corium ssp. corium. Mycenastrum corium is a worldwide species commonly collected in Colorado and the western United States but also collected from the eastern United States (Smith & Smith 1973).