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Species Information
Summary: Roseodiscus subcarneus most easily found by observing the dead patches of liverworts or mosses it produces by growing on them. Other features include a pink-colored, cup-shaped fruitbody, relatively long stem, and microscopic characters including clavate spores. Hengstmengel(1) explains some of the nomenclatural history of this species and a different species that grows mainly on decorticated wood or chips of deciduous trees, Hymenoscyphus subcarneus (Schumach.) J. Schroet., now called Phaeohelotium carneum (Fr.: Fr.) Hengstm.
Roseodiscus subcarneus is found at least in WA, (Kanouse), AB, MI, NH, and NY, (Seaver), ON, (White), Poland, and reported in Slovakia, PQ, (in Baral). There is a BC collection labeled Helotium destructor at Pacific Forestry Centre.
Upper surface: fruitbody (0.04)0.05-0.13(0.15)cm across fresh, shallowly cup-shaped to saucer-shaped; whitish but with a distinct pale pink tint, (Baral), up to 0.05cm across disc but usually considerably smaller, up to 0.1cm high, when young papillate, then elongating, enlarging at top, becoming nearly spherical with a rather deep pore; disc becoming shallowly funnel-shaped, finally saucer-shaped with turned up margin, when dried similar in color to exterior and stem or sometimes more opaque creamy yellow; margin smooth, elevated, obtuse [blunt], (White), reaching 0.05cm across, but often much smaller, (scarcely visible to the naked eye), gradually expanding and becoming nearly spherical, at maturity concave with upturned margin; "hymenium similar in color to the outside of the apothecium" [but does not mention what this color is], (Seaver)
Flesh: waxy-cartilaginous when dried (White)
Underside: implies that the fruitbody as a whole is "whitish but with a distinct pale pink tint"; margin of large fruitbodies "often undulating to somewhat irregular", (Baral), in dry condition pale yellow or hyaline-yellow; smooth, not wrinkled in drying, (White), smooth (Seaver), "ochraceous-buff" (probably Ridgway color) when fresh, (Kanouse)
Stem: 0.06-0.12cm x 0.02-0.035cm, abruptly delimited from cup, concolorous, pale ochraceous toward base, exterior nearly smooth under a hand lens, at higher magnification delicately pubescent, especially near margin, (Baral), about 0.03-0.05cm long, long for size of fruitbody, cylindric, slightly widened at juncture with disc, rather firm, not wrinkled in drying; hyaline-yellow in dried material; entirely smooth or more rarely with a thin scattering of white cottony hyphae around base, (White), relatively long, reaching length of 0.03-0.05cm, slender and slightly broadened at junction with cup, (Seaver)
Microscopic: spores free (5.2)6-8.5(10) x (1.8)2-2.6(3) microns, in KOH about 6-8 x 2-2.3 microns, of variable length, slightly to mainly strongly clavate or pyriform or even somewhat cuneate (triangular), smooth, colorless, biseriate within living asci; asci 52-66 x 6.5-7.5(10) microns, in KOH 42-57 x (5.5)6-7(7.5) microns, 8-spored, apex strongly conic, apical ring deep blue in IKI, of the Calycina-type ("rather thick in optical section, widest in its upper part which extends to the very apex"), 0.6-1 microns high and 0.9-1.1 microns wide (dead state), base attenuated or rather broad, arising from croziers; paraphyses cylindric to slightly clavate, even in dead state 3-7 microns shorter than the asci, terminal cell (11)16-37 x 2.8-3.5(4) microns, in living state multiguttulate in the upper 25-40 microns by spherical refractive vacuolar bodies, these vacuolar bodies disappearing in KOH and invisible in dead cells; medullary excipulum near ectal excipulum of a broad textura porrecta, in center of a small region of dense textura intricata (individual cells here in KOH 12-25 x 3-4 microns), ectal excipulum of a horizontally (10-20 degrees) oriented colorless textura prismatica of thin-walled cells, individual cells (12)20-45(67) x (6)10-13(16) microns, externally covered by a loose network of 3-5 microns wide eguttulate hyphae, towards margin of textura porrecta oriented at about 10 degrees, cells (in KOH) 13-18 x 2.5-4 microns, "not differentiated from covering hyphae which terminate here in somewhat projecting hair-like ends" that contain in the living state low-refractive droplets, in stem of textura porrecta, (Baral), spores 4.5-6 x 2-2.5 microns, pyriform [pear-shaped], biseriate, content not granular; asci 40-50 x 5-6 microns; paraphyses simple [unbranched] or once or twice forked, scarcely or not at all widened at tip, 3-3.5 microns wide, (White), spores 4.5-6 x 2-2.5 microns, clavate, the narrow end directed downward, biseriate; asci 8-spored, reaching a length of 40-50 microns and width of 5-6 microns, clavate; paraphyses "simple, or occasionally branched, scarcely enlarged above, 3-3.5 microns in diameter", (Seaver), excipulum "composed of broad parallel hyphae, with thin-walled cells about 20-30 x 10 microns, lying at a very low angle to the surface and covering a flesh formed of more slender loosely wavy hyphae", ascus pore turns blue with iodine, (Dennis(2))
Habitat / Range
growing on and apparently killing various species of liverworts and mosses: Jungermania sp., Dicranum flagellare, (Seaver), on a liverwort on a log, parasitic on liverworts and mosses, (Kanouse), single, sparse, or rather numerous, growing on and apparently killing various species of Jungermaniaceous liverworts and mosses, originating from the leafy branches, all collections in September except once in July, (White)
Similar Species
Roseodiscus rhodoleucus and Roseodiscus equisetinus grow on dead Equisetum and should be watched for in the Pacific Northwest. The spores of the former measure 9-12 x 5-6 and are non-septate (Dennis(1)). The spores of the latter measure 8-13 x 2.5-3 microns and are 1-septate at maturity (Dennis(1)). There is a collection from WA deposited as Hymenoscyphus rhodoleucus at the University of Washington. At least one species of small pink discomycete occurs on dead Equisetum in British Columbia, but Stamnaria is another genus that may produce pink fruitbodies on dead Equisetum (collection listed as Stamnaria persoonii at the University of British Columbia, although spores were measured at (14)15-18 x 4-5 microns, narrower than some measurements such as 15-18 x 5-8 in Dennis(1)). Psilachnum inquilinum (P. Karst.) Dennis was identified by Haines(1) with seven collections examined from Washington on Equisetum during the course of his Master''s thesis. These are not pink but white to cream-colored. He says the sessile to short-stemmed cups are up to 0.1(0.15)cm across, the exterior "sparsely covered with hairs which appear white under the dissecting scope, disc often slightly darker than the exterior", the spores 7-8 x 2-2.5 microns, clavate-cylindric, the paraphyses narrowly filiform-lanceolate, up to 2 microns wide, exceeding asci by no more than 8 microns; the hairs 3-4.5 microns wide and up to 50 microns long, colorless, smooth, thin-walled, irregularly cylindric, septate, slightly constricted at the septa, cells 10-15 microns long.
