Dear colleagues, 

no, i do not know Durella macrospora, or even know where to place the genus rightly. 
Just looked at this thread as i saw it was done by Tsuyoshi. 
I do answer, because i liked to say sorry for missing to publish my results concerning systematics and nomenclature of genus Stamnaria. Perhaps one reason, Tsuyoshi why your concept of this genus in Mycosystema 32(3) 2013 could not be right or complete. 
I will explain more in detail at separate thread, or personal message, just tell i do agree with species concept as presented by Danny Haelewaters & al. 2018 in publication of S. yugrana. 

My main question to you all: Zotto wrote "There is in fact an amyloid and an inamyloid form of D. macrospora", so far so good and debatable. I differed between Stamnaria americana as having strictly anamyloid asci, versus amyloid S. laetissima comb. ined. (bas. Peziza laetissima Cesati 1846) in wide sense. 
When reading description of S. americana from Hokkaido in Tsuyoshi & al. 2013, this does agree with the identified species, except it got J+ asci. 
So that raises the question: will this ascomycete be more close to S. laetissima, or shall it represent amyloid S. americana. Shall this be proved by sequencing a wider range of samples of S. americana - laetissima alignement? I do know plenty of specimen from N hemispere, yet to Java, Indonesia.

Yes, i do intend to publish hitherto unpublished names of several Stamnaria spp., as these names are more than 20 years provisorial, so i could not ID new reports correctly.
My E-Mail: gruberwin0529 [at] gmail.com without space and @ for sure

Best regards, Erwin

Stamnaria-americana

Stamnaria

Equisetum infected by genus Stamnaria

Hallo lieber Zotto!

Yes, time to come back here after long delay. Thanks a lot for your kind response! 
As with you, i argued that loss of amyloidy of apical ascus structure is not necessarily a gap diverging species' in general. As you said, sometimes yes, yet not as a rule. Still the loss of amyloid substance (whatever it is chemically) is no big matter as long the structure works well. Hence i could imagine J+ beside J- races within species, still capable of fully fertile interbreeding. 
From that point of view, Tsuyoshi & al. may be right by IDing as Stamnaria americana.
Consequently my Id keys using an-amyloidy of S. americana will work in America and Europe, but perhaps not in far E Asia.
I am as well curious for Tsuyoshi's answer and experience. You migh have a look at linked new occurrences of Stamnaria (prob.) americana, and S. sp. indet. at iNaturalist. Most of these were found by me on photos of Equisetum hyemale by watching closely.

Indeed, it is high time to publish new species validly. This shall happen before end of 2020. Perhaps Danny Haelewaters, or another colleage liked to contribute with sequencing data. I need to create a good concept for publication. we may discuss at separate thread about partizipation. 

Best regards to all, keep care of your health

Erwin

Zotto and all together,

so we turn back to amyloidy and use of apical ascus ring. 
Well, you may be right when telling that fungi with inamyloid asci are correlated with (more) drought tolerance in general, and perhaps these may not discharge spores at same speed as amyloid relatives. 
In special case of Stamnaria americana, ecologic conditions of infected host populations will be pretty the same at all continents. In fact chances of "far" distance dispersal are by appoximately zero, as sustained by own observations as well as infection experiments. Disciform ascocarps are best adapted to shrivel at !relatively! lower air humidity, and rehydrate quickest in contact with water. Saying spores, relatively large, with thin walls, will consequently be released at air humid weather conditions in cold season. As foggy, or rainy days with low to zero wind. Ascospores won't be transported for long distance, or surpass dehydration, but infect shoots at close proximity. Main reason why disjunct, small populations of hosts stay free from infection, as well as large ones, when distance to infection sources is too wide. 
I do assume this is the same in all occurrences of this species, again supported by visible conditions of infected, and free horsetail occurrences. Saying "the wetter the better" plus "the closer the better" for the acomycete, not necessarily their hosts. 

Loosing the amyloid structure, so spores will perhaps be expelled somewhat less wide, won't change a lot to that coevoluted adaption, hence will have happened by chance.
As with many ascomycetes this feature of apical structure will be neccessary for dispersal, this could be lost in case of Stamnaria americana. What may, will happen.

May you agree, colleagues?

Erwin

Dear Tsuyoshi, 

since you wrote in 2013 you had not found another occurrence of Equisetum hyemale infected by apparent amyloid Stamnaria americana, i liked to bring a potential new find to your attention. 

This is not in the vicinity of Higashimogoto, but in the southern part of Hokkaido, still needs verification at time, as the fungus is not clearly visible at photo. Till now i turned out to interprete right, please see linked occurrences of Stamnaria at my first response to here. 
Stamnaria in southwestern Hokkaido? 

As this place is not too far from Sapporo, it shall be easy to prove for the fungus.

Best regards

Erwin