Cyathus stercoreus, the "dung-loving bird's nest", has 39 different possible MAT-A's, and 24 MAT-B's. This means that there are a total of 936 (39×24) different genders, and an arbitrary fungus will be able to mate with 874 (38×23) of them.John Kellden
Image: University of Guelph
h/t: FJ