Observation 94069: Stemonitis splendens Rostaf

When: 2012-05-06

Collection location: Frances Slocum State Park, Luzerne Co., Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

No specimen available

Proposed Names

70% (2)
Eye3 Eyes3
Recognized by sight
Used references: Audubon

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Missing line
By: Clive Shirley (myxo)
2012-05-22 02:42:51 CDT (-0400)

There was a missing line of text from my last posting thats now been fixed sorry about this.

By: Patrick Harvey (pg_harvey)
2012-05-21 18:23:52 CDT (-0400)

400X doesn’t require immersion oil, so you should be able to get away with not
using a cover slip.

By: Dave W (Dave W)
2012-05-21 10:57:00 CDT (-0400)

I think I’m getting close to being able to at least attempt some sort of procedure….

First observe a sporangium (correct singular word for “sporangia”?) with a hand lens to determine if and where the mesh (network of capillitii… capillitia?) may be observable. Then try to view the targeted area with a scope. Certainly 400x is more than enough magnification for this. Then, if I am correctly extrapolating upon what I have learned so far, determine the diameters (diagonals) of the subpolygonal regions, and this constitues the mesh measurment.

Irene points out that one wants to avoid crushing the mesh (capillitii). This does appear to present a problem, because the part one wishes to view must be mounted within a plane that is normal (perpendicular) to the line of sight through the scope. Maybe it’s possible to carefully scrape some material from a sporangium?

I think
By: Irene Andersson (irenea)
2012-05-21 09:43:03 CDT (-0400)

the mesh (it’s the outer surface of the sporangia) is best viewed with a loupe. I don’t know how to measure it though..

You could try to look at a sporangium in the microscope without crushing it..

So then one would look for…
By: Dave W (Dave W)
2012-05-21 09:34:03 CDT (-0400)

capilitium. From what I have found online, this appears to mean that one looks for threadlike structures. Are these found on the surface of a strand? If so, then is there a particular area within a strand, and a best way to mount/view?

Mesh size would be
By: damon brunette (damonbrunette)
2012-05-21 09:02:51 CDT (-0400)
the capilitium that is surrounding the columella I believe.
I am not certain what is meant by “mesh size.”
By: Dave W (Dave W)
2012-05-21 08:58:33 CDT (-0400)

Does this refer to the thickness of an individual strand within the fruit body? If so, does one measure this thickness at… the tip? the midsection? or the point of attachment to substrate?

Looking again at my spore photo, I notice a few spores that qualify for “broadly elliptical.” Although my scope is not good enough to discern amongst the various types of ornamentation, it looks to me (when I zoom in) like these spores are rather smooth.

Stemonitis species
By: Clive Shirley (myxo)
2012-05-21 03:40:38 CDT (-0400)

Hi Dave,

There are around 18 known species of Stemonitis fortunately most of these can be eliminated from been a possibility due to there small size. The most likely possible species are S. fusca, S. splendens and S. axifera mainly as these are common, widely distributed and of a large size.

S. fusca has a small mesh size <30µm reticulated spores 7.5-9µm diameter.

S. splendens has a large mesh size >30µm, warted spores 7-9µm diameter.

S. axifera has a small mesh size <30µm, smooth spores 5-7µm diameter.

S. fusca is normal id by the reticulated spores but looks like it could also be done by mesh and spore size. At 400x you should be able to measure the mesh size well enough. There are macro diffrances between these but unless you are famila with them its not going to help much.

Thanks Clive.
By: Dave W (Dave W)
2012-05-20 10:56:26 CDT (-0400)

This is one big reason why I post observations here… to learn things. Sometimes I’ll accompany a post with a high level of confidence, because I don’t know of any other possibility, and so “That’s what I call it.” Granted, information gleaned from field guides is often incomplete. But for an amateur like me, manuals (books and online) are almost always the starting point.

Unfortunately, my max 400x scope is probably insufficient for examination of spore ornamentation. So the posted spore photo is about as good as it gets for this obs. The measuring scale inside my scope reads out a bit small. Multiplying by 1.2, I would say these subglobose to globose spores are in the 7 to 9 mu range.

What else
By: Clive Shirley (myxo)
2012-05-20 04:58:03 CDT (-0400)

I am at a loss how any one can recognise a Stemonitis with out looking at it with a microscope and measuring the spores, mesh size and noting the spore texture. So it can be key it out.

What else besides S. splendens
By: Dave W (Dave W)
2012-05-07 07:41:49 CDT (-0400)

could this possibly be?

Created: 2012-05-06 21:01:34 CDT (-0400)
Last modified: 2016-07-05 09:19:38 CDT (-0400)
Viewed: 638 times, last viewed: 2017-10-31 14:33:10 CDT (-0400)
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