Mucormycosis (also called zygomycosis) is a rare infection caused by organisms that belong to a group of fungi called Mucoromycotina in the order Mucorales.At one time these fungi were called Zygomycota, but this scientific name has recently been changed.ucormycosis (also called zygomycosis) is a rare infection caused by organisms that belong to a group of fungi called Mucoromycotina in the order Mucorales.