A new Allacta xizangensis sp. nov. (Blattodea: Ectobiidae: Pseudophyllodromiinae) is described and assigned to the polygrapha species group. Four known species, A. robusta, A. bimaculata, A. transversa, A. ornata, are re-described and illustrated based on type material and specimens kept in the collection of Southwest University (SWU), Sun Yat-Sen University (SYSU), Hebei University (HBU), China and Institute of Zoology, Chinese Academy of Sciences (IZCAS) and the Russian Academy of Sciences (ZIN). The hitherto unknown male of A. transversa is described with a special display of its genitalia. A key is given to identify the males of Allacta from China. The tarsomere ultrastructure of all the legs of A. ornata was examined by scanning electron microscopy.