Summary:
Features include 1) a mould-like, cottony growth on many kinds of fungi, especially Aphyllophorales, white becoming rose-colored or red, with dark red pimple-like perithecia, 2) large spores (usually over 30 microns long) that are verrucose and conspicuously apiculate, 3) an anamorph in nature forming a delicate yellowish to red mycelium on which erect conidiophores are standing, each conidiophore bearing a number of conidia at the top that appear as white tufts, and 4) in addition to conidia 18-30 x 8-10 microns, the anamorph produces thick-walled cells (chlamydospores) that are 60-90 x 15-20 microns.

Microscopic:
SPORES (20)25-30(38) x (3)4-5(7.5) microns, fusiform to lanceolate, prominently verrucose (verrucae up to 1 micron high), two-celled, septum median, conspicuously apiculate, apiculus 4-6 microns long, often curved; ASCUS 150-160 x 5-7 microns, cylindric, spore-bearing part 100-125 microns long, apex thickened, with a pore; PERITHECIA gregarious, 250-460 x 150-360 microns, ovate, obovoid to obpyriform, "immersed in subiculum with apex free, typically red but sometimes brown, purplish red in KOH", papillate or nonpapillate, papilla obtuse; hyphae 2.5-5 microns wide, "the cells usually short, smooth, septate, much branched and loosely interwoven, walls smooth, KOH+ purplish red"; CONIDIUM (16)18.5-27.5(35) x (7)8-9.5(13) microns, cylindric to narrowly clavate, (0)1-2(3)-septate, with conspicuous basal hilum, "produced singly and appearing to adhere in a dry radiating head"; conidiogenous cells 20-40 microns long, 3-4.5 microns wide at base, 2-3(3.5) microns wide at tip, conidia forming at tip, "the conidiogenous locus proliferating percurrently with annellides sometimes seen, or sometimes proliferating sympodially as a short, thin-walled rachis"; CONIDIOPHORES "arising in aerial mycelium, indefinite in length and barely morphologically distinct from vegetative hyphae, main axis 3-5 microns wide, verticillately branched, each branch a conidiogenous cell"; Blastotrichum-like chlamydospores "comprising large, 1-5 celled globular masses 60-90 x 15-20 microns, brown, reddish brown, olivaceous to black and often sclerotioid", (Rogerson), SPORES 25-35 x 4-6(7.5) microns, fusiform, verrucose, (verrucae up to 1 micron high), ends apiculate, apiculi 4-6 microns long, with acute tips, spores 1-septate, septum median; ASCUS 140-160 x 5-7 microns, "with apex thickened, penetrated by a pore"; PERITHECIUM "semi-immersed in the subiculum", 250-460 x 150-360 microns, "red, KOH reaction with the whole perithecium turning purple", perithecial papilla 80-150 microns high, 75-140 microns wide at base, 2.3-6 microns wide at top, tip obtuse, "of pseudoparenchymatous texture, with cells in divergent files, becoming narrower toward the ostiolar canal and more rounded towards the outer surface"; SUBICULAR HYPHAE 2.5-5(8) microns wide, loosely interwoven with cells becoming swollen; CONIDIUM 18-30(36) x (6)8-10(12) microns, cylindric to elliptic, equilateral, 1-3-septate, colorless, "with central or occasionally laterally placed basal hilum"; conidiogenous locus with no proliferation observed, forming 1 conidium; conidiogenous cells by 3-5 in a verticil, 20-50 microns long, 3-4.4 microns wide at the base, proliferating progressively; forming 1-10(15) conidiogenous loci; CONIDIOPHORES arising from aerial hyphae, hardly or not differentiated from these, 3-5 microns wide, branching verticillate or irregular; thick-walled cells "formed in irregular globular masses in terminal position on lateral branches or in hard subglobose to globose sclerotia, among aerial or submerged hyphae", brown or red, "with cells subglobose to globose, held by 1-5", wall smooth; aerial mycelium scanty or abundant, (Poldmaa)

Notes:
Hypomyces rosellus was collected from BC by Kevin Trim (on the underside of Polyporus), It was also reported from BC in Redhead(5). It has been reported from NY, Estonia, Poland, and Ukraine, (Rogerson). It is probably cosmopolitan, with both the teleomorph and anamorph common: there are records from CA, NY, Cuba, Argentina, Estonia, Lithuania, Portugal, Russia (northwest, Siberia), Ukraine, United Kingdom, Iran, Japan, and New Zealand, (Poldmaa). There is a collection from VA at the University of British Columbia. The M Beug photograph represents a collection that probably came from near Sisters Oregon.

Synonyms and Alternate Names:
Corticium roseocremeum Bres.
Hypomyces purpureus Heinr.-Norm.