These were growing on a dead, fallen stem of Filipendula ulmaria together with Ollas and Trichopezizellas. Ammonia fumes turned the apos reddish orange. 

Asci with eight spores. Spore measurements: 

(6.7) 7.2 - 8.2 (9.1) × (1.8) 1.81 - 2.1 µm
Q = (3.5) 3.6 - 4.27 (4.3) ; N = 10
Me = 7.8 × 2 µm ; Qe = 4

Fungi of Temperate Europe mentions that P. rubrotinctum should have four spores per ascus. But asco-sonneberg.de says eight and in centrodeestudiosmicologicosasturianos.org the asci also seem to have eight spores. When I examined the sample the spores seemed to be in two rows and sometimes gave the impression of 4-spored asci. So... could this be P. rubrotinctum or is there another possibility?