Description: "Body oval with rather pointed anterior end or elongate with sides nearly parallel and rounded ends; shoulders or lateral projections absent. Tegument with or without spines. Papillae on ventral surface form three rows of discrete papillae. Oral sucker small, terminal or subterminal. Caeca simple, terminate medially or posteriorly to testes without uniting. Testes some developed or not. Cirrus-sac median, claviform, slender anteriorly. Cirrus smooth or may bear small tubercles. Genital pore typically immediately postbifurcal but anterior to bifurcation in some species. Ovary rounded, intercaecal, intertesticular. Mehlis' gland median, pre-ovarian. Laurer's canal reported in some species. Uterine coils occupy third quarter of body. Excretory vesicle small; pore dorso-subterminal. In intestine and/or caeca of birds (manily Anseriformes, Ardeiformes, Charadriiformes, Galliformes, Gruiformes, Phoenicopteriformes) and mammals (Mormoopidae, Muridae, and perhaps other chiropterans); cosmopolitan. Type species N. triserialis Diesing, 1939" (Bray et al., 2005).
Life Cycle: “Adults live in the cecum of aquatic birds and mammals. Eggs pass in the feces, undergo a period of development, and a miracidium emerges. The miracidium infects aquatic snails, and passes through the mother sporocyst, mother redia, and daughter redia stages. Cercariae emerge from the daughter redia and leave the snail. They encyst as metacercariae on aquatic vegetation or even on the shells of other molluscs. When eaten by another bird or mammal, they excyst in its intestine and mature in its cecum” (University of Alberta).
Sources: Bray, R.A., Gibson, D.I., and Jones, A. 2005. Keys to the Trematoda, Vol. 2, p. 393.
Department of Biological Sciences, University of Alberta. http://www.biology.ualberta.ca/parasites/ParPub/text/index/param03i.htm