The structure of vasa deferentia and spermatophores has been described in Parapenaeopsis stylifera. The male reproductive system consists of two symmetrical halves; each half bears testis, vas deferens and an ejaculatory duct. Each testis comprised of two to three short, broad and milky white lobes; vas deferens is divisible into proximal, medial and distal parts. The proximal vas deferens (PVD) is a convoluted mass made up of an extremely long and thin tube having elongated rod like spermatozoa. The median vas deferens (MVD) is broad, straight, somewhat flattened and bears many membranous folds internally and contained complete spermatophores; the distal vas deferens (DVD) is straight and cylindrical tube. The ejaculatory duct is a simple dilation with a tubular basal part tapered posteriorly for extrusion of spermatophores. The spermatophores are minute, spindle shaped bodies present in large numbers in each ejaculatory duct; the size varied from 0.148 to 0.161 mm; each spermatophore bears six to eight rows of regularly arranged spermatozoa. Histological studies reveal no internal partitioning of either vas deferens or ejaculatory duct.Keywords: Parapenaeopsis stylifer, vasa deferentia, spermatophore
