edvin_johannesen's Identifications

Hemitrichia montana (Morgan) T.Macbr., 1899, seems the best fit but spores are larger.
Sporophores: sporocarps 0.6 - 1.3 mm and plasmodiocarps up to 3 mm long. Peridium: membranous, shining/iridescent, reddish brown, dehiscing from above, persisting below as almost petaloid lobes; two layered by TL, with an outer granular coating on an ochraceous-yellow membrane, +/- wrinkled. Hypothallus: yellowish. Capillitium: threads long, sparsely branched, 4.0-5.5 µ, smooth or with minute spikes (oil immersion), 4 left-turning spiral bands, often loose, ends with short, single spinule or capitate where spiral bands tightly aggregate. Spores: (12.1)13.9-15.1(17.9) (avg. 14.9) µ, globose with many having irregular oval to subglobose shapes, ochraceous in mass, bright yellow by TL, minutely spinulose. Habitat: nivicolous, on ~1 cm thick Alnus branch.

Hemitrichia montana (Morgan) T.Macbr., 1899, seems the best fit but spores are larger.
Sporophores: sporocarps 0.6 - 1.3 mm and plasmodiocarps up to 3 mm long. Peridium: membranous, shining/iridescent, reddish brown, dehiscing from above, persisting below as almost petaloid lobes; two layered by TL, with an outer granular coating on an ochraceous-yellow membrane, +/- wrinkled. Hypothallus: yellowish. Capillitium: threads long, sparsely branched, 4.0-5.5 µ, smooth or with minute spikes (oil immersion), 4 left-turning spiral bands, often loose, ends with short, single spinule or capitate where spiral bands tightly aggregate. Spores: (12.1)13.9-15.1(17.9) (avg. 14.9) µ, globose with many having irregular oval to subglobose shapes, ochraceous in mass, bright yellow by TL, minutely spinulose. Habitat: nivicolous, on ~1 cm thick Alnus branch.

An exceedingly rarely reported and very exciting find!!! I do not see what else these beautiful myxos could be except Diderma rufostriatum, which have been recorded fewer than 30 times worldwide to date -- only in three countries in Western Europe and a single observation in western Australia (per GBIF). Microscopy will be done to confirm, but the descriptions in the literature are very clear and these fit the description perfectly as far as I can tell. And, to make this all the more amazing, these were all found in dry leaf litter and on tiny twigs in my very own front yard by my friend @graysquirrel !