Piedraia
Piedraia is a genus of fungus within the Piedraiaceae family in the Capnodiales order. There are 2 known species (according to Species Fungorum);
 Piedraia hortae 
 Piedraia quintanilhae 

Former species;
 P. hortae var. paraguayensis  = Piedraia hortae
 P. javanica   = Piedraia hortae
 P. malayi   = Piedraia hortae
 P. sarmentoi   = Piedraia hortae
 P. surinamensis   = Piedraia hortae
 P. venezuelensis  = Piedraia hortae

Piedraia hortae is responsible for causing black piedra. References

Dothideomycetes genera
Animal fungal diseases
Capnodiales