The asci are definitely unitunicate, and a member of Helotiales is very probable in which apically thick-walled asci are common. 

I am not sure if the branch was still attached and the fungus drought-tolerant.

Regrettably you did not mount in water. It is a recent collection? It is important to know the contents of the living spores and paraphyses.

The ectal excipulum at the flanks os of globose cells?

Hans-Otto, thank you very much for your comments. Yes, this collection is recent, from just two days ago, and I still have a part of it in a wet chamber (the rest I put in the dryer yesterday). I just tried to scope the fresh tissue in water; the result is in the attached photo. Sadly, I couldn't see any free spores and I'm thinking I should give these cups a few more days to mature before scoping them again. The dark cells in pictures are indeed from the excipulum. 

I don't know about drought-tolerance of these. There has been a lot of rain this winter. In any case, they were growing on free standing sticks/branhes, at the height of about 150-180 cm. It's a deciduous shrub and I'll check later if some of it grows leaves, so we can identify it.

Ha, this is very helpful. You can see the strongly refractive contents in the paraphyses, a very typical feature of Mollisia. I actually suppose such a relationship, despite the unusual spores.

Would be great to identify the shrub. Yes, when these grew on standing dead branches, they must withstand drought for a couple of weeks.

Your area is mediterranean, is it? It may be that these cups do not occur during summer but show only a limited tolerance.

Zotto

Zotto, thank you again. Glad that you found the last photos useful. I didn't, but I may learn a few things with this fungus. I hope we will soon know what the shrub is and I will keep visiting to see what happens with the olive colony. 

Yes, the climate in the area is kind of Mediterranean, with rain in the winter and cool and dry summers, with lot of fog. 

Sava

What you still can do is to make the KOH test. About 30-50% of Mollisia spp. show a more or less striking yellow KOH.reaction of their VBs (refractive vacuoles). This yellow reaction is seen in the surrounding medium but disappears rapidly, so you must watch immediately. Either put a piece of an apo in a drop of KOH (ca. 1-5%) and look under the bino whether the KOH turns yellow,  ot add a small drop of KOH to the water mount and view under 100x.

Zotto, the yellow reaction in KOH is rather strong. After 5 minutes, I could still see it clearly and after 10 minutes it's still there, but much faded.

Wonderful! This reaction is often overlooked and therefore rarely mentioned in the literature. When you mount in KOH and press on the slide, you wil miss it.

So we can be quite sure that it is a Mollisia. Good would be to observe living asci and free spores. It is quite probable that the spores are septate when still in the living asci, but this should be proved. Also the oil drop pattern in the mature, freshly ejected  spores  is important.

Septate spores are rather rare in wood-inhabiting Mollisias.

I suppose now we have a proof you asked for. I'm probably attaching too many photos, but here they are, just in case you find something interesting in them. For the last  photo, I added a drop of Melzer's. 

This weekend I'm going to revisit the place and try to learn something about the shrub, and also check how the discos are doing.

Yes, this gives much new insights. Indeed the spores are in the mature living asci 1-3-septate. Did you measure also living spores? Maybe they are a bit larger? Likewise the asci.

Zotto, thanks again for your comments. In this last session, I measured only three spores: 17.5x4, 17x4, 15x4. There weren't many free ones, so I measured those that appeared largest to me, and they were all within asci. I'm wondering how one getsreliable mearurements in this situation, the main concern being recognizing mature spores. In the composite photo that I posted at the beginning, there were two spores that looked 5-septate and the larger measured 24x5. So I'm thinking that if I had a mature enough specimen, then perhaps the majority of its free spores would be 5-septate. 

I hope I'll find more of these cups soon and then I'll look at samples from serveral of them. I will take any advice you might have about the procedure. I printed a copy of your 1992 paper, perhaps it's all said there...

Actually when you are not sure with 5-septate spores it could still be that they were "plasma bidges" between oil drops, this is sometimes difficult to decide on the dead state.

And if they are truely 5-septate, it can still be that these are overmature ones.

If I had a scale to your photos I could measure more than 3 in the living asci. Often the spores are a little smaller in this case, but in the present species I do not see much difference to outside.

Zotto, I went back to the site yesterday and am pleased to report that the cups are still there, more shriveled than a week ago, but that seems to be how they are: with enough moisture, they open up.

Fortunately, the shrub is alive. Most of it is dead, but there are buds at enough branch tips and soon we will see its leaves. For experts, the photos I took yesterday would probably be enough to tell the shrub genus.

It was interesting to find an asexual form growing alongside the cups. It has round, olive-green conidia, about 4 microns. A likely anamorph, I guess.

The photos are in the attached pdf. The second file contains measurements and microshots from which I selected asci and spores to measure. I used only one cup for this, mounting one slice of it in water and another one in Melzer's. If you think more measurement would be worthwhile, please let me know what you would do.

Thanks again, it's been a nice learning experience.

When you do comparison of measurements in water and MLZ you must cautiously distinguish for the water fraction which asci are alive and which not, otherwise it makes no sense. Your measurements in water are just the same as in MLZ,  so i guess you did not include the living mature ascus on your third new pic.
See http://www.gbif-mycology.de/HostedSites/Baral/

This third image shows above right a spore with a thick gel sheath!

Indeed spores are 3-septate, one can see it in free living spores by slight constrictions. Asci arise from croziers.
What I still miss is a median section  to show the excipulm at margin and flanks.
Zotto

Zotto, thanks again for comments. Really appreciated. I'm just starting to pay attention to live vs. dead material under the scope, so there's going to be some learning. I'll study your paper when I get a chance. 

In the attached file, the first three photos show excipular cell from near the cup margin. The next three are from the flanks or near cup base. If you don't see what you want in these photos, please let me know what you'd like to be done differently. 

The last three photos show some branching 'binding' hyphae that looked unusual to me. I tried to find them on another mount, but couldn't. 

Lastly, a macro feature that I haven't mentioned so far: these cups are quite sticky (resinous?). When I'm making sections, they stubbornly get themselves attached to needles and tweezers.

Yes, dark brown globose cells as they occur in many Mollisias. The branched hyphae could belong to a parasite.

In any case, with a razor blade it should be possible to make a median (vertical) section, at least at the flanks, with yome luck also at the margin. In addition, the anchoring hyphae (subiculum), usually also brown in Mollisia, might be of interest.

Zotto, thanks again for the instructions. This time I took vertical sections through dried cups to avoid struggling with the fresh fungus sticking to my instruments. Interestingly, the slices opened up (spread out) in Melzer's in a few minutes. I hope (but am not sure) that these photos will show more of the excipulum than the previous ones. Anyway, the first photo is taken at 10x and shows the positions for the next four shots taken at 40x. 

The remaining photos are an attempt to show the anchoring hyphae. I took a vertical section down to the substrate and including a piece of it. You can see it in the photo that begins this sequence (page 6). In the remaining photos I tried to capture the tissue between the wood and excipulum. There was no subiculum that I could discern through the dissecting scope. 

If there is something more that I can do, it will need to wait for a week because I'll be out of the country. When I'm back, I'll revisit the location to get a photo of the shrub with its leaves. 

Many thanks!

This is better but only the survey photo shows the undisturbed situation. Any pressure should be avoided. Under bright field it should be possible to make closeup photos of the texture.

On the beforelast pic I see some brown hyphae which are anchoring hyphae. So there seems to be no abundant subiculum.

This is Nipterella parksii, originally described as Belonidium parksii from dead stems of various shrubs (Vaccinium, Rhamnus, Physocarpus, etc.) in California, occurring in early spring.

I've only seen herbarium specimens, which still showed the nice green hymenium but the ectal excipulum was darker. It is nice to see this one fresh, I'll have to keep an eye out for this here in British Columbia.

Ok, no pressure. Is this any better?

Joey, thank you very much for the name. I'm looking at  "A reassessment of Belonidium" (Dennis), which is the only source I can see online, and everything mentioned there does seem to match. 

Hello Sava, the description is in the following paper (I just emailed it to you):

Cash, E. K. (1936). Some ascomycetes new to California. Mycologia, 28(3), 247-252.

Great, Joey! Never seen this. Of course I know Dennis' description.

Again a case where the yellow KOH-reaction seems to have been overlooked. 

No sequence seems to exist in GenBank. I suspect that placement in Nipterella is not justified, depending on where the type N. duplex belongs. N. duplex reminds me somewhat of Mollisia atlantica ined., which has a bit smaller spores.

It seems curious that Dennis and also Müller & Defago still laid so much stress on spore septation or did they see more distinguishing features against Mollisia?

If I remember correctly, Dennis considered Nipterella in Encoelioideae but distinct from other genera because of the amyloid asci and septate ascospores. Starback described N. duplex in Niptera but stated that it probably belonged in its own genus and remarked that the ectal excipulum was Mollisia-like.

Nipterella parksii definitely in Mollisiaceae but it would be great to have sequences of N. duplex to see if they form a clade or not. The bright hymenium, scurfy ectal excipulum comprised of monilioid cells, and ascospores are quite distinct. I realize now that I have access to N. tsugae specimens including the holotype; I'll have to take a look at these soon and see if it belongs in this family or not.

I almost forgot about these species but they are very striking, I'll keep an eye out for them.

This means you have a sequence of parksii? Does it show affinities with known Mollisia species?

I also wonder if there is a scutum-like structure in parksii, judging from the present micro-pics.

And I wonder if the gel sheath around the spores is real and if it stains lilaceous in Cresyl Blue as I observed in Nimbomollisia.

I got an okay quality ITS sequence from one specimen and it is in Mollisiaceae but not really close to any of the available reference sequences if I recall correctly. 

Looking through my pictures of N. parksii, I don't see any gel sheath in cresyl blue or water, but Sava's pictures do seem to show some apparent ascospore sheaths.

I found this species yesterday! I made a collection of mostly-immature apothecia on a fallen Alnus rubra branch. It was among the damp alder leaf litter at the shore of a small lake. Hopefully they mature in the moist chamber and I will get some cultures from ascospores.