Opalinata

Opa·li·na·ta (o″pə-lĭ-naґtə) in older classifications of protozoa, a subphylum of the phylum Sarcomastigophora, including parasitic, flat, leaflike, multinucleate species; they are usually found as endocommensals in anurans and less often in fish, salamanders, and reptiles. They have cilia arranged in multiple oblique longitudinal rows over the entire body surface, but differ from the Ciliophora in having only one type of nucleus (i.e., no differentiated micronuclei and macronuclei) and in reproducing sexually. This group contains just the single class of Opalinatea.