In this study, supplementary information on the morphology of the siphonostomatoid copepod Caligus quadratus Shiino, 1954 (Copepoda: Caligidae) is given based on the new material collected from the gills of the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) caught in the Gulf of Antalya, Turkey. The morphology of C. quadratus is re-examined for the first time by adopting a recently developed visualisation technique by Kamanli et al. [1]. Appendages of Congo red stained specimens of C. quadratus were dissected and scanned using confocal laser scanning microscope (CLSM) and the CLSM images were processed using Dristhi software programme. 3D reconstructions of some confusing appendages were visualised using Drishti. Line drawing was used to depict the habitus of both female and male C. quadratus. Key diagnostic characters of C. quadratus are presented together with the newly observed additional taxonomic characters. In addition, previously misinterpreted and simply overlooked features in the previous descriptions of C. quadratus are also re-described. This is the first report of C. quadratus from the Mediterranean Sea and the Atlantic bluefin tuna constitutes a new host record for this caligid copepod.

在这项研究中，基于从大西洋蓝鳍金枪鱼g（Thunnus thynnus（Linnaeus，1758））中捕获的the的新材料，提供了有关虹吸食足类co足类Cali足类（Caligus quadratus Shiino，1954）形态的补充信息。土耳其安塔利亚湾。通过采用Kamanli等人最近开发的可视化技术，第一次重新检查了C. quadratus的形态。[1]。刚果红染色标本的附录使用共聚焦激光扫描显微镜（CLSM）进行解剖和扫描，并使用Dristhi软件程序处理CLSM图像。使用Drishti，可以对一些令人困惑的附件进行3D重建。用线描描绘雌性和雄性中华C的习性。介绍了C. quadratus的关键诊断特征以及新近观察到的其他分类学特征。另外，还重新描述了先前描述的四角梭菌中先前被误解和简单忽略的特征。这是来自地中海的四头C的第一份报告，大西洋蓝鳍金枪鱼构成了这种cal足co的新宿主记录。