How are Obregonia and  Trichodiadema different from each other?
Obregonia Obregonia, the artichoke cactus, is a genus of cacti with a single species, Obregonia denegrii. The species is endemic to the state of Tamaulipas in Mexico.
Onchocercidae The Onchocercidae are a family of nematodes in the superfamily Filarioidea. This family includes some of the most devastating human parasitic diseases, such as lymphatic filariasis, onchocerciasis, loiasis, and other filariases.