Description: "Trunk swollen in anterior portion, posterior portion slender. Hypodermal nuclei confined to anterior portion of trunk. Anterior trunk with 2 fields of spines on at least 1 sex. Anterior field may be incomplete dorsally. Proboscis cylindrical, with or without a swollen area, armed with numerous longitudinal rows of hooks. Neck conspicuous. Proboscis receptacle double-walled, inserted at base of proboscis. Lemnisci not bound to body wall at distal ends. Testes in anterior trunk. Four tubular cement glands. Parasites of aquatic birds. Distribution circumboreal” (Hoffman and Williams Jr., 1999).
Sources: Hoffman, G.L. and Williams Jr., E.H. 1999. Parasites of North American Freshwater Fishes, Second Edition, p. 300.
Schmidt, G.D. 1973. Resurrection of Southwellina. Witenberg, 1932, with a description of Southwellina dimorpha sp. n., and a key to genera in Polymorphidae (Acanthocephala). J. Parasitol, Vol. 59, Issue 2, p. 299-305.