Explorations in Brazil to find parasites of the red imported fire ant, Solenopsis invicta Buren, have uncovered a new species of the Tetradonematidae, Tetradonema solenopsis n. sp. The nematode parasite was fatal to about 25% of the colony. The female nematodes are large and sausage shaped and the males are small and difficult to find, which is typical of the genus. The ant is a new host record for tetradonematids.
Keywords: Nematoda; Solenopsis invicta; Tetradonema solenopsis; ant; biological control; new species; taxonomy.