Phaeocalicium polyporaeum is a tiny mycoparasitic fungus, seen here on its most common host, Trichaptum cf biforme, although it has also been reported on Trametes versicolor.
You'll have more luck checking Trichaptum - I've never found them on Trametes yet. There's also a similar looking species, Gliocladium polyporicola, which grows on Stereum hirsutum, so may as well check all the small shelf fungi!