摘要
The aetideid copepod Bradyidius angustus was originally described 67 years ago based on two males collected from the Pacific coast of central Japan. This species has been the only one with the female unknown in the genus. Based on specimens from the Seto Inland Sea, Japan, this study describes the female of B. angustus for the first time, together with a complementary description of the male and a brief description of the later copepodids. The female has no seta on the medial margin of the exopod terminal segment of the antenna, which is a unique character within the genus. The distinction of the female from the currently known 18 congeners is also possible by a combination of a body length less than 2.0 mm and ornamentation on the legs, the antenna exopod or the mandible basis. The male is distinct from all congeners with regards to leg 5, the ornamentation of the endopod of legs 3 and 4, or the rostrum. The male specimens have some minor differences from the figures of the original description. The later copepodids (CIV and CV) have a stockier prosome than the adult, but are similar to the adult in some easily observable morphologies, by which they could be possibly identified to the species. This species is considered to be an epipelagic form. Discussion is also made on a past description of B. armatus from Japan.
摘要译文
Aetideid Copepod Bradyidius Angustus最初是在67年前根据日本中部太平洋海岸收集的两名雄性所描述的。该物种是该物种中唯一的雌性未知的物种。基于日本塞多内陆海洋的标本，这项研究首次描述了安加斯图斯的女性，以及对男性的互补描述以及后来的copepodids的简要描述。雌性在天线的外部末端段的内侧边缘上没有seta，这是该属中的独特特征。通过小于2.0毫米的身体长度和腿部装饰，天线外脚架或下颌骨的结合，也可以通过雌性与当前已知的18个同类物的区别。雄性在腿5，腿3和4的内脚架的装饰方面与所有同类物不同。男性标本与原始描述的数字有一些较小的差异。后来的copodids（CIV和CV）比成年人具有更具浓郁的优点，但在一些易于观察的形态中与成年人相似，可以将它们鉴定为该物种。该物种被认为是表皮形式。还讨论了过去对日本的Armatus的描述。
Hiroshi Ueda [1];Tetsuya Nishikawa [2];. First description of the female of Bradyidius angustus (Calanoida, Aetideidae) with descriptions of the male and copepodids[J]. Plankton and Benthos Research, 2025,20(1): 84-92