Schlieren texture has been observed in S(C) and S(C)A liquid-crystalline phases. We found that defects of strength s = +/- 1/2 exist in the S(C)A phase in addition to those of s = +/- 1 observed in the S(C) phase. The existence of the s = +/- 1/2 wedge disclination is explained by taking account of a screw dislocation. This complex defect consisting of a wedge disclination and a screw dislocation, i.e. a dispiration, serves as a simple test to confirm the antiferroelectric (S(C)A) structure.