Dear colleages, i have been absent again for a while here. Having found a small population of Equisetum hyemale hosting Stamnaria americana in Pfäffikon, CH, i am back to report this finding. 
Although Stamnaria americana is known from some places in northern Switzerland it shall be a rather rare ascomycete here, and this site might still be unknown. I could not find a Swiss website to report it, thus decided to report here.
Position: 47.196568, 8.768407 and 47.197588, 8.772588 in two places at Staldenbach, Pfäffikon.
At two rather small patches of the host plant, maybe someone here could prove if the occurrence is known. I will add a link to further images at flickr later on.