Abstract: 【Aim】The distinctive arrow-shaped morphology and large size of the spermatozoa of Gampsocleis gratiosa makes it a useful model to explore spermiogenesis in Tettigoniidae. In order to better understand the mechanism of spermiogenesis, especially the mechanism of nucleus morphogenesis and arrow-shaped acrosome formation in katydids, the nuclei of spermatid and spermatozoa of G. gratiosa were observed in the present study. 【Methods】 The testes of G. gratiosa in sexually mature males were used as the materials. We observed the nuclei of spermatid and spermatozoa by transmission electron microscopy, ordinary optical microscopy, fluorescence microscopy and with H&E and DAPI (DNA specific probe) staining method. 【Results】 According to the morphology and structure, the nuclei during spermiogenesis of G. gratiosa were divided into four phases: rounded, leaf, prismatic and mature phases. During the spermiogenesis of G. gratiosa, there are two globular structures at the rounded phase, one is the nucleus and the other is pro-acrosome. The cytoplasm droplet, which would be derelict along the tail of spermatozoa at the mature phase, contains DNA. 【Conclusion】 The observation revealed that spermatid nucleus of G. gratiosa undergoes dramatic morphological changes during its spermiogenesis. The nucleus shaping is driven by cytoskeletal microtubules, and the chromatin reorganization is together with nucleus shaping. This study will be the foundation to clarify the molecular mechanism of spermiogenesis in Orthoptera.

Key words: Orthoptera, Gampsocleis gratiosa, nucleus, pro-acrosome, ultrastructure, H&E staining, DAPI, spermiogenesis