Notes:
Growing in grass, solitarily and in small clusters of 2 or 3. Same species and location as Obs 371402 and Obs 319081. Macro: Pileus glabrous, dull whitish with buff colors in the disc upon maturity and also some slight grayish/blue tones present, the cap sometimes cracking in age and/or upon loosing moisture, developing a more vibrant brown hue around the cracks, also a couple of mushrooms that weren’t initially collected developed a pinkish/magenta hue/tone after about 2 days in full sun (see last photo), not sure if its anomalous or a genuine characteristic, I’ve never noticed/observed it before; Lamellae concolorous with pielus (maybe a tad lighter shade?), emarginate/sinuate with a prominent decurrent tooth at the stipe, edges somewhat jagged in age, becoming brownish near margin; Stipe firm and tough, concolorous with pileus and lamellae, though frequently a darker grey tone; somewhat equal or tapering downward to a ‘pinched’ base, generally glabrous when younger, becoming fibrillose, fibrils becoming brownish when mature and also somewhat when handled, finely pruinose near apex; odor nondistinctive to slightly farinaceous when fresh, becoming more pungent after drying; did not taste. Micro: Basidiospores, elliptical/ellipsoid to ovoid, apiculate and monogutulate and/or with granule contents, mostly smooth though some exhibiting some faint ornamentation (crassospores), especially noticeable in Melzer’s, amyloid – becoming a darker blue within 5 minutes; ~ (5.4) 5.5 – 7.0 (8.0) x 4.0 – 5.0 (-5.3 – 5.5) μm, (L’ = 6.07 μm; W’ = 4.57 μm; Q = 1.08 – 1.63; Q’ = 1.33; N = 40); Hymenial cystidia absent, consisting only of basidia and basidioles, both of which containing one to several oil globules; Basidia clavate to subclavate, mostly 4-spored, rarely 2-3 spored (sterigmata generally around 2-4 μm long, rarely up to 6-7 μm in length), ~ 25 – 34 × 6 – 8 μm (avg. = 28.3 × 6.89 μm); Basidioles very similar to basidia, slightly more slender/shorter; Pileipellis a hymeniderm, elements consisting of globose to subglobose to broadly clavate (infrequently subpyriform) terminal cells, sometimes branched, ~ 15 – 25 × 5 – 9 μm; Lamellar trama essentially regular, multi-layered, bottom layer made up of parallel, elongated cells with upper layer consisting of irregular hyphae, clamps present; Stipitipellis a cutis, hyphae thin walled and with clamps, not sure if caulocystidia is present or if its terminal hyphal ends, very similar to pileipellis.

Images

Lamellar hyphae
Stipitipellis and possibly caulocystidia
Stipitipellis and possibly caulocystidia
Stipitipellis and possibly caulocystidia
Spores in Melzer’s and water after about 5 minutes
Spores in Melzer’s & water after about 5 minutes
Spores in Melzer’s and water after about 5 minutes
Hymenial edge
Hymenial edge
Lamellar trama
Pileipellis
Pileipellis
Pileipellis
Stipitipellis
Stipitipellis
Stipe trama
Pileipellis
Pileipellis
Stipe trama hyphae
Stipitipellis and possibly caulocystidia
Stipitipellis and possibly caulocystidia
Spores in Melzer’s and water after about 1 minute or so
Same group of fruitings 2 days after initial observation.

Proposed Names

29% (1)
Recognized by sight: Smooth, but minutely bumpy cap with pale flesh beneath cracking cuticle, emarginate gills, tapered-fibrillose stipe, saprophytic habitat (grass/lawn); farinaceous/mealy odor becoming a bit rancid in age and upon drying
Based on microscopic features: Pileipellis a hymeniderm/cellular, amyloid spores, relatively short basidia, hymenial cystidia absent, caulocystidia present/clavate/variable; clamp connections present/frequent
Based on chemical features: Amyloid spores
57% (1)
Based on microscopic features: spores amyloid
29% (1)
Recognized by sight: Paler-whitish-gray basidiocarps
Used references: A Revision of Dermoloma (Arnolds 1991,1993)
Based on microscopic features

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= Observer’s choice
= Current consensus

Comments

Add Comment
Thank you Else,
By: Chris Cassidy (cmcassidy)
2019-08-10 09:12:09 EDT (-0400)

I have indeed read that. That paper was one that really helped me deduce this one down to Dermoloma. There’s not much (if any) literature on the genus with respect to North America, and likely nothing at all of which focuses on the Eastern & Southeastern US. Everything I can find generally describes darker colored basidiomes, haven’t found anything that really resembles this whitish collection. Thanks so much for your input, it’s highly valued!!

Dermoloma
By: else
2019-08-09 23:30:33 EDT (-0400)

Dermoloma seems a very good match.
did you read Arnolds’ paper in Persoonia 14: 519-532 (1992) – to be downloaded form https://www.repository.naturalis.nl/ – this focuses on Europe, but might give you leads.

After some reading, I believe the most likely contender (based on macro/micro features)
By: Chris Cassidy (cmcassidy)
2019-08-09 19:08:16 EDT (-0400)

other than Dermoloma, is Hygotrama (formerly Camarophyllopsis subgenus Hygotrama) based on the hymeniderm pileipellis, or possibly Porpoloma, however the gills of Hygotrama are apparently more widely spaced and decurrent, spores inamyloid, with longer basidia and a nondistinctive odor/taste. The latter (Porpoloma) resembles Dermoloma with respect to macro features, however the pileipellis is a cutis of cylindrical hyphae. I’ve been reading Arnolds (1992) and I’m pretty sure that this collection is Dermoloma – Does anybody have any other possible proposals? I personally don’t really know how to go about sequencing, but if anybody is interested, please let me know!

Thanks Dave,
By: Chris Cassidy (cmcassidy)
2019-07-05 11:39:46 EDT (-0400)

I’ve found this in grassy areas for the last year or two now. Have been somewhat puzzled, but believe I’m getting closer, step by step. Dermoloma may be the genus, but I’m still a little hesitant. Plus, hardly any literature out there with respect to North America, let alone the Southeast US. I’ve really been trying to narrow this down to genus and this is the best fit I have. Forget about a species though, I’ve not found anything close at that level. I’ve been hoping some MO members could help me. Porpoloma was another similar possibility, but micro was way off. I’ve been digging/looking at some of these monotypic/undescribed genera within the Agaricaceae and Tricholomataceae s.l., but again, hard to find much of anything. And everything I do find usually requires translations.

Nice find, Chris!
By: Dave W (Dave W)
2019-07-04 11:59:54 EDT (-0400)

New genus for me… Dermoloma. Lotta nice work here! If this turns out to be Dermoloma, then I imagine quite a few MO members gain knowledge here… for that matter, even if this is something other than Dermoloma.

Other close members
By: Chris Cassidy (cmcassidy)
2019-06-30 17:05:43 EDT (-0400)

In Tricholomataceae sensu stricto, that exhibit the typical tricholomatoid morphological features generally have hymenial cystidia (ie. Dennisiomyces, Porpoloma, Corneriella and Pseudotricholoma etc.); and those without said cystidia have either verrucose spores (ie. Leucopaxillus) and/or inamyloid spores (ie Albomagister and Tricholoma etc.). Thus, I believe this could be a legitimate contender for Dermoloma; hymenial cystidia absent, hymeniderm pileipellis and amyloid, smooth spores.