Various species in the Porphyrio genus of the Rallidae family, including Porphyrio porphyrio, Porphyrio madagascariensis, Porphyrio poliocephalus, Porphyrio indicus, Porphyrio pulverulentus, and Porphyrio melanotus.
How often have the words marsh hen and purple swamphen occurred in a corpus of books? (source: Google Ngram Viewer )