A new species of Dichelyne (Nematoda: Cucullanidae) parasitizing fish of the family Pimelodidae in the Amazon estuary, northern Brazilian coast.

A new cucullanid, Dichelyne (Dichelyne) jutubensis n. sp., collected from the intestine of Propimelodus eigenmanni (Van der Stigchel, 1946), from the Amazon estuary on the northern coast of Brazil, is described based on light and scanning electron microscopy. The prevalence of infection was 39.6% (36 infected fish/ 91 examined). Morphologically, the nematodes lacked a ventral sucker, and the number of caudal papillae in males identifies them as members of the nominotypical subgenus Dichelyne of the genus Dichelyne. The new species differs from its congeners by the presence of a conical, spiny appendage at the tip of the tail and in the number and distribution of its 10 pairs of caudal papillae: six pre-cloacal, one adcloacal, and three post-cloacal. This new species represents the fourth record of the genus in Brazilian territory and the first record for estuarine waters in northern Brazil, with Propimelodus eigenmanni registered as a new host for the genus.