Operculate and inoperculate asci

[rich ard]

I presume the Microscopy sub-forum is for microscopes and microscopy techniques and not for discussion micrcscopic apparances of fungi?? Please move this thread if in the wrong place.

Posch has found some orange-red discomycetes growing on soil, possibly in association with moss (but no burning) that could well be an Octospora sp. See the thread:

Octospora sp. ?

In trying to key them out using E&E I note that Octospora have 'operculate asci' but I have no experience of viewing asci with 'lids'.

At what stage of ascus development does the operculum become visible?

I had assumed that the 'lids' are visible even on immature asci but maybe I am mistaken.

Perhaps the lid / operculum develops as the ascus matures so only becoming visible when the ascus is fully mature and about to discharge its spores??

When viewing a squash of the possible Octospora sp I found numerous asci with intact rounded tips. Only after a prolonged search did I find these three



The left one looks to me as though it does not have an operculum (ie it is inoperculate) and is opening to discharge it spores.

The middle ascus (discharged) looks as though there may be an opercum on the right side below the tip.

The one on the right has also discharged its spores but I cannot tell if operculate or inoperculate!

Can anyone make sense of this for me please?

Richard

[Chris Yeates]

hi

this a perfectly valid part of the forum to be posting this

I haven't a lot of time at the moment but as a starting point it should be pointed out that the terms operculate and inoperculate are fine but they do conceal a wide range of ascus "dehiscence" (rupturing in some way to eject the spores) types

as a general rule broadly rounded ascus tips like yours coupled with broad ascospores (again like yours) would strongly suggest an operculate asco

those asci are behaving in an odd way - are they in any sort of stain?, because that will have the effect of killing the asci and their spores, often accompanied by alteration of their shape

as a general rule always look at fresh material in water first - you can add stains and reagents later

I shall return to this thread - promise - (and will try to post some useful images as well)

cheers

Chris

[fairplay]

Chris, another question for when you're back from the p.. oops, corner shop.

I did the BMS Discomycete workshop at Wells, Norfolk in 2002, and quite honestly it was pretty heavy stuff.
We were all lucky to receive Brian Spooners 'not for publication' Keys to try out and test before they were published, but what I would like clarification on is where you talk of adding stains or reagents 'later'.

I saw people doing this, but cannot remember if the slide was taken out of the scope or whether let's say Melzers, was drawn through the slide whilst on the stage.

If on the stage, naturally you would need to ease off the pressure of the oil immersion lens I assume ?
And also by placing tissue the opposite side of the cover slip to where you place a drop of Melzers, this 'draws' the water out and the Melzers in.
But isn't there a chance the Melzers is diluted this way ?

Although were all received illustrated material about the different types of asci and the way they opened and ejected their spores, I never understood it in a way in which I can pass on any constructive advice, so am quite happy to let Chris take the stage (and avoid making a fool of myself)

Neil.

[rich ard]

Thanks to you both,

Yes Chris, the picture was taken after the squash had been stained with Congo Red.

I have just had a look in water and all asci have uniformly rounded tips, none appear to be damaged in the way shown in my earlier picture.

I cannot reach a conclusion for those orange discos - I have followed through the E&E key for both operculate and inoperculate asci. I wonder if the specimens are past their best and have lost excipular hairs, if those had been present I could make a good case for Melastiza chateri.

That aside I would like to learn more about the two types of asci when you get time.

Richard