RESUMO
Plagioscion squamosissimus (Heckel, 1840) (Osteichthyes: Sciaenidae) is considered piscivorous and is a generalist species endemic to the Amazon region. This fish is an important part of the natural ecosystems in which it occurs and provides basic functional components in the food web. The genus Neoechinorhynchus Stiles & Hassall, 1905 is distributed worldwide and parasitizes fish and turtles, but there are few reports of parasites of this genus in South America, due to the high diversity of fish that can be found in this region. A new species of thorny-headed worm (Acanthocephala: Neoechinorhynchidae) is described from P. squamosissimus from Guajará Bay, Belém, Pará, Brazil. In general, the unique characteristics of the hooks on the anterior end of the proboscis and the length-to-width ratio relationship separate this new species from other described species in the genus Neoechinorhynchus. Although the species in this genus are mostly found in North America, the dearth of species known from the neotropics may be due to the lack of studies in this region.
