mossgeek's Identifications

High elevation chaparral and mixed forest, Pseudotsuga macrocarpa, Pinus ponderosa, Quercus chrysolepis, Hesperoyucca whipplei.
Growing on leaves and twigs submerged underwater ~4 in deep in mildly turbulent stream from snowmelt runoff. Area had been covered in snow two weeks previously, but it was absent at the time of the observation, with last traces visible in between peaks at the highest elevation.

Most caps clearly developing and expanding underwater; others starting above water out of saturated margins of the stream. “Aquatic” caps bursting through layer of algae on surface of the water, but no algae on the underwater substrate.
Underwater caps alabaster at button stages, expanding to brown with white cracked pattern. Above-water caps more dome-shaped, velvety, zonate. Both hygrophanous. Gill margins white; consistent feature.
Stipe lacking annulus, extraordinary flexible for Psathyrella. Rigid inner layer (revealed by microscopy to be a dark conglutination) and a squishy, plastic-bag-like outer layer (consisting of lighter hyphae in pyramidal ridges).

Spores deposit purple black. Spores cigar brown. KOH+ fuscous. With apical pores. [11.8] 12.25-13.18 [13.9] x [6.2] 6.62-7.2 7[7.8] μm
Q [1.71] 1.74-1.89[2]

Spores measured from spore print deposited from mushroom cap that developed underwater; evidence for this is the presence of diatoms in the cross section of this mushroom.

On this same cross section are spores that appear to have germinated on the gills.

From microscopy, compared to P. aquatica the basidia of this specimen are more obtuse and pleurocystidia more elongate. The spores and cheilocystidia are similar.

High elevation chaparral and mixed forest, Pseudotsuga macrocarpa, Pinus ponderosa, Quercus chrysolepis, Hesperoyucca whipplei.
Growing on leaves and twigs submerged underwater ~4 in deep in mildly turbulent stream from snowmelt runoff. Area had been covered in snow two weeks previously, but it was absent at the time of the observation, with last traces visible in between peaks at the highest elevation.

Most caps clearly developing and expanding underwater; others starting above water out of saturated margins of the stream. “Aquatic” caps bursting through layer of algae on surface of the water, but no algae on the underwater substrate.
Underwater caps alabaster at button stages, expanding to brown with white cracked pattern. Above-water caps more dome-shaped, velvety, zonate. Both hygrophanous. Gill margins white; consistent feature.
Stipe lacking annulus, extraordinary flexible for Psathyrella. Rigid inner layer (revealed by microscopy to be a dark conglutination) and a squishy, plastic-bag-like outer layer (consisting of lighter hyphae in pyramidal ridges).

Spores deposit purple black. Spores cigar brown. KOH+ fuscous. With apical pores. [11.8] 12.25-13.18 [13.9] x [6.2] 6.62-7.2 7[7.8] μm
Q [1.71] 1.74-1.89[2]

Spores measured from spore print deposited from mushroom cap that developed underwater; evidence for this is the presence of diatoms in the cross section of this mushroom.

On this same cross section are spores that appear to have germinated on the gills.

From microscopy, compared to P. aquatica the basidia of this specimen are more obtuse and pleurocystidia more elongate. The spores and cheilocystidia are similar.

On living branch of white fir. Thallus imperceptible. Spore mass on stalk up to 1 mm tall. Spores 2-celled, brownish, ornamented with ridges in pinwheel pattern; ( 11.8 ) 12-13 ( 13.8 ) x ( 4.5 ) 5-5.5 ( 5.8 ) μm.