Hello,
Here is another Physarum on decaying plants which I am trying to identify. I only have about 15 fruiting bodies (maybe more will grow) and they are old I think. The myxocarps are very rich in lime almost fluffy, the spores are like collapsed but few were examinable and are round to slightly oval, not ornamented and unless it is my imagination, i am seeing a faint line across some. Those which are starting to collapse or shrivel show this line stronger (line of weakness ?). The lime nodules are chunky and quite rounded at edges. Spores 11-12 um (so it fits too). I am sorry that I do not have better material!