The Black dwarf porcupine (Coendou nycthemera), also known as Koopman's porcupine, is a species of New World porcupine in the family Erethizontidae endemic to northern Brazil. It occurs in Amazonia east of the Rio Madeira and south of the Amazon River. It was described as Coendou koopmani by Charles O. Handley, Jr. and Ronald H. Pine in 1992, but was subsequently found to be identical to a species described in 1818.