The fungus Bartheletia paradoxa is a 'living fossil' (an organism that has remained essentially unchanged from earlier times and whose close relatives are usually extinct).  It is found on Ginkgo leaf litter.  It has unique characteristics among the basidiomycetes.   In autumn the asexual stage (anamorph) forms on newly fallen leaves.  Later, the sexual state (teleomorph) is formed as minute black hemispherical leaf spots, each surrounded by a grey halo.  The spots consist of thick-walled, dark brown teliospores.  

host

Photograph on the host tree; note substrate and host in your comments.   Ensure that your photos show the black telia; we recommend that these are examined on a specimen.

Found on Ginkgo leaf litter.

See Scheuer, C., Bauer, R., Lutz, M., Stabentheiner, E., mel'nik, V.A., Grube, M. 2008. Bartheletia paradoxa is a living fossil on Ginkgo leaf litter with a unique septal structure in the Basidiomycota.  Mycological Research, 112 (11) 1265-1279.  Available here.  or full text here.