Macaroni penguin been considered separate species, but the close similarities of their DNA sequences has led some, such as the Australian ornithologists Les Christidis and Walter Boles, to treat the royal as a subspecies of the macaroni. The two species are very similar in appearance; the royal penguin has a white face instead of the usually black face of the macaroni. Interbreeding with the Indo-Pacific subspecies of the southern rockhopper penguin ("E. chrysocome filholi") has been reported at Heard and Marion Islands, with three hybrids recorded there by a 1987–88 Australian National Antarctic Research Expedition. The macaroni penguin is a large, crested
Macaroni (horse) entering the straight and held off the sustained challenge of The Oaks winner Queen Bertha to win by one and a half lengths. At Newmarket in October he walked over in the Select Stakes and was then retired to stud. Macaroni was retired to his owner's stud at Hooton until 1866 when was sold for 7,100 guineas to Baron Meyer de Rothschild who moved the stallion to his stud at Mentmore. Macaroni sired several successful racehorses, including the 2000 Guineas winner Macgregor but was more notable as a sire of broodmares. He was the damsire of the Triple Crown winner