Neotropical Monogenoidea. 28. Ancyrocephalinae (Dactylogyridae) of piranha and their relatives (Teleostei, Serrasalmidae) from Brazil and French Guiana: species of Notozothecium Boeger and Kritsky, 1988 and Mymarothecium gen. n. Journal of the Helminthological Society of Washington, 63(2), July 1996: 153-175. 161 [Zoological Record Volume 133]