Observation 164998: Morchella diminutiva M.Kuo, Dewsbury, Moncalvo & S.L.Stephenson
When: 2014-05-10
Herbarium specimen reported
0 Sequences

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Thanks, Dave.
By: Rocky Houghtby
2014-05-16 08:04:15 EDT (-0400)

Morchella micro features are interesting in that the paraphyses, asci and spores are highly variable in shape and size. I have made lots of measurements and intend to update these two observations with averages. I have limited time to work on these things.

The diminutiva type differs from the esculentoides type in several pertinent ways:

1) The apicies of the paraphyses on the ridges of both species range from clavate to capitate. In the diminutiva type the clavate to sub capitate apex is more common and in general there is less variation cell to cell. In the esculentoides type there appears to be at least two distinct intermediate apex shapes between clavate and capitate with no one cell shape standing out more than the other. Additionally, the paraphyses in diminutiva are uniformly hyaline while those in esculentoides appear to have a higher refractive index as a result of cell contents, perhaps oil droplets.

2) the cells in the hymenium of both species react to koh, in diminutiva there appears to be a more noticeable reaction, the asci, hyphal elements and paraphyses darken more readily en masse. Kuo notes that diminutiva tends toward a brown reaction and esculentoides an ocheraceus reaction. I cannot confirm this assertion currently, but I can confirm that there is a different reaction to koh between the two collections, with the diminutiva type producing a much higher contrast.

3) this one is ambiguous, but the general layout of the hymenium appears to differ in the two collections, with paraphyses appearing more abundantly between asci in the diminutiva type. The determination here is occluded by the lack of differentiation between highly refractive clavate paraphyses and developing asci in the esculentoides type. As the asci mature they tend to project out of the hymenium and develop a chamber in the upper half of the cell in which spore can be made out through a primordial soup. Asci (tentatively) appear to be more abundant on the hymenium of the esculentoides type.

I would like to point out that this is the first Asco that I have studied microscopically. I would like to spend more time with these collections before making confident statements about their microscopic differences, but for now I can attest that there ARE microscopic differences between the two.
The high variation of dimensions in this genus (even the mature spores rang +\- 10 microns at times!) make determination a challenge. I personally feel that average lengths of cells would be useful in species delimitation, but I’m not sure I have the desire to invest much more time into Morchella besides these two collections.


Nice micro, Rocky.
By: Dave W (Dave W)
2014-05-16 03:31:11 EDT (-0400)

Anything that points toward diminutiva and/or away from esculentoides

I’m not sure now
By: Rocky Houghtby
2014-05-11 09:37:56 EDT (-0400)

There isn’t a hardwood forest in this state that doesn’t have Ash, even a sapling can host. Plus, you have a good point about the vertical arrangement of the pits. I’ll post the micro tonight if I can.

You’re welcome, Rocky.
By: Dave W (Dave W)
2014-05-11 09:28:47 EDT (-0400)

In my experience, the diminutiva type(s) often start out as “grays”, just like the “esculenta” types. I have also IDed examples with thickened stipe base.

But the macroscopic line between these two groups seems to be anything but obvious.

Thanks for your comment, Dave.
By: Rocky Houghtby
2014-05-11 09:16:45 EDT (-0400)

I do not consider americana to be a valid epithet and instead elect to use the epithet that was supported by extensive microscopic and molecular research at the time of publication.

This Morel was found in a homogenous stand of Elm. M. cryptica may be possible, I should be able to delimitate between the two by looking at the hyphal elements on the ridges. I have collected M. diminutiva in TN beneath tulip poplar, I found it to have less pits, yellowish ridges and a stipe that does not bulge. I will consider diminutiva when I examine the collection more closely.

Rocky, the current NA name…
By: Dave W (Dave W)
2014-05-11 07:02:14 EDT (-0400)

for the classic yellow morel is Morchella americana. At least this is the name applied within the NA Asco book. Also M. cryptica = M. ulmaria, a look-alike elm/ash associate known from the midwest, is said to be paler with flatter ridges. The one seen here may fit this description, although an immature “yellow” will generally have pale ridges.

The morel seen in this obs has a relatively small number of pits that are vertically elongated. So I think M. diminutiva (and maybe even M. virginiana) may be considered. These morels are generally smaller than M. americana and appear in forests of living tulip poplar, ash, or hickory.

Created: 2014-05-10 22:28:49 EDT (-0400)
Last modified: 2015-02-28 16:22:09 EST (-0500)
Viewed: 289 times, last viewed: 2017-10-07 18:31:16 EDT (-0400)
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