Myrmecia nigriceps is a species of ant endemic to Australia. A member of the genus Myrmecia in the subfamily Myrmeciinae, it was first described by Austrian entomologist Gustav Mayr in 1862. These ants are large, varying from 19 to 23 millimetres (0.75 to 0.91 in) in length. However, colonies contain workers that are much smaller, usually half the size of normal workers.