Page "Dorado" Paragraph 1

Even though the name Dorado is not Latin but Spanish, astronomers give it the Latin genitive form Doradus when naming its stars ; they are treating it ( like the adjacent constellation Argo Navis ) as if it were a feminine proper name of Greek origin ending in-ō ( like Io or Callisto or Argo ), names that have a genitive ending in-ūs.