Polyplacidae is a family of lice in the suborder Anoplura, the sucking lice. Lice in this family are known commonly as the spiny rat lice. The family has a cosmopolitan distribution. As of 2010 there were 193 species. These are small to medium-sized lice. They are usually sexually dimorphic. They have 5-segmented antennae and small, slender, clawed forelegs. Their middle and hindlegs may be almost equal in size, or the hindlegs may be larger. Genera include: