First record and new species of the parasitoid wasp Chaenotetrastichus Graham (Hymenoptera: Eulophidae) for the Neotropical Region, with notes on its biology and a key for the species of the genus.

Chaenotetrastichus neotropicalis sp. nov. from the Atlantic Forest, Brazil, is described and illustrated. This new species is associated with a species of the pompilid wasp Auplopus Spinola (Hymenoptera: Pompilidae) and it represents the first record of the genus for the Neotropics. A key for the extant species of the genus Chaenotetrastichus Graham is also presented.