Dichelyne (Cucullanellus) tornquisti n. sp. (Nematoda: Cucullanidae) from corocoro grunt, Orthopristis ruber (Cuvier, 1830) (Perciformes: Haemulidae) from Southeastern Brazil.

Dichelyne (Cucullanellus) tornquisti n. sp. is described from the intestine of the marine fish Orthopristis ruber (Haemulidae) of Rio de Janeiro, Brazil. The new species differs from the congeners by the location of the deirids (same level) and the excretory pore (posterior) in relation to esophagus-intestinal junction and by papillae 5 to 9 not forming a subventral line. It is the first Dichelyne species described from fish family Haemulidae in the Brazilian coastal zone.