Observation 169679: Megacollybia rodmani R.H. Petersen, K.W. Hughes & Lickey

When: 2014-07-13

Collection location: Wharton State Forest at Batsto Lake, New Jersey, USA [Click for map]

39.6466° -74.6446°

Who: I. G. Safonov (IGSafonov)

Specimen available

> A single basidiome growing in a pitch pine thicket.
> Cap diameter </= 5 cm; stipe length </= 10 cm.
> The spore print is pure white.
> Stature type is collybioid/tricholomoid/naucorioid (from How to ID Mushrooms to Genus VI).
> Microscopy:
[21/1/1]; L x W = (7.4-) 7.9-9.0 (-9.4) x (5.7-) 6.0-6.5 (-7.0) um
L x W = 8.4 × 6.3 um
Q = (1.21-) 1.28-1.43 (-1.46)
Q = 1.34
I only measured spores with visible apiculus, and none of those were round or subglobose. Surprisingly there was little variation in spore size.
The typical spore shape was ovoid/broadly ellipsoid.
The shape and size as well as internal content (1-2 “oil droplet” or multiguttulate) are consistent with Megacollybia spore descriptions from www.bio.utk.edu/mycology/Papers/MEGACOLLYBIA.pdf.

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Add Comment
By: I. G. Safonov (IGSafonov)
2014-07-15 00:04:22 PDT (-0700)

Thanks for your input. The spore profile supports Megacollybia (vide supra), so you could be right after all.
Visual identification of M. rodmani is very straightforward, but in this case, the combination of habitat, pale cap and narrow gills didn’t evoke the species concept readily.

Gill attachment…
By: Dave W (Dave W)
2014-07-14 15:52:18 PDT (-0700)

is fairly variable for M. rodmani. Also, I often find it growing seemingly terrestrially, from buried wood. Often a coniferous stand includes a few birch or other harwoods. With a saprobe like the platterful, the question often is “what kind of tree used to be here.”

My “could be” level of confidence is basically a function of the reported habitat.

By: I. G. Safonov (IGSafonov)
2014-07-14 13:59:33 PDT (-0700)

Is M. rodmani known to grow in coniferous woods? My mushroom appeared to be mycorrhizal, not saprobic. The cap is too pale and the gill attachment is sinuate/uncinate.

Created: 2014-07-13 17:28:39 PDT (-0700)
Last modified: 2014-07-15 00:06:19 PDT (-0700)
Viewed: 62 times, last viewed: 2018-04-11 02:59:16 PDT (-0700)
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