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 and cheese has remained popular in the United States. A recipe called "macaroni and cheese" appeared in the 1824 cookbook "The Virginia Housewife" written by Mary Randolph. Randolph's recipe had three ingredients: macaroni, cheese, and butter, layered together and baked in a hot oven. The cookbook was the most influential cookbook of the 19th century, according to culinary historian Karen Hess. Similar recipes for macaroni and cheese occur in the 1852 "Hand-book of Useful Arts", and the 1861 "Godey's Lady's Book". By the mid-1880s, cookbooks as far west as Kansas and Festus, Missouri, included recipes for macaroni and cheese casseroles. Factory production