The new sp. is described from 1 3 and 4 $. Holotype 3 and allotype S: Brazil: Sao Paulo State, Fazenda Santana do Rio Abaixo (24°14’55”S – 46°00’27”W), alt. 569 m, 30-XI-2002, collected in tandem; deposited in author’s collection. It is compared with the original description of I. ancilla Sel., I860 (the type sp. of the gen.) and with specimens identified as that sp. Diagnostic illustrations and notes on Idioneura distribution and biology are provided.