It has 23,328 distinct mating types. Individuals of any mating type are compatible for mating with most other mating types. There are two genetic loci determining the mating type, locus A with 288 alleles and locus B with 81 alleles. A pair of fungi will only be fertile if they have different A and different B alleles; that is, each mating type can enter fertile pairings with 22,960 others.