Yuma is one species of Ricordea. Aquacon's site says: "Ricordea yuma is readily distinguished from Ricordea florida by the fact that the Ricordea Yuma has pseudotentacles on the oral cone, while Ricordea florida does not. Also, Ricordea florida often has numerous mouths and elongated irregular shapes, while Ricordea yuma is usually circular, with only one mouth."
HTH,
Mariner