Abstract
The mallophagan genus Aquanirmus, parasitic on grebes (Podicipidae), is revised. Four new species and one new subspecies are described: emersoni ex Podiceps grisegena, occidentalis ex Aechmophorus occidentalis, podilymbus ex Podilymbus podiceps, bucomfishi ex Podiceps auritus, and bahli chamberlini ex Poliocephalus dominicus. The geographic and host distributions of the parasites are discussed. It is pointed out that geography plays an important role in the distribution of the species of Aquanirmus.