Argulus is a crustacean branchiuran parasite that causes severe problems in aquaculture throughout the world. Conventionally, Argulus spp. are identified through the morphological descriptions. In the recent years, polymerase chain reaction amplification with nuclear ribosomal RNA sequence coupled with morphological description is becoming standard for the species-level identification of Argulus spp. The present study investigated Argulus sp. in snow trout, Schizothorax richardsonii, using morphological and molecular tools. Morphologically, the parasite had branched dorsal ridges of the carapace, clubbed shaped anterior respiratory area, curved shaped posterior respiratory area, three relative sharp teeth and chitinous shovel peg on the fourth swimming appendages. Females Argulus sp. were larger in size than males in their length and width. Morphological characteristics and 18s rRNA study revealed that the parasite species was Argulus japonicus. A phylogenetic tree was constructed to examine relationships between these A. japonicus sequences and existing archived sequences. The maximum distribution of pathogenic argulid was observed in the dorsal fin, followed by the ventral fin and pectoral fin. The present study contributes to the first species-level morphological and molecular identification of A. japonicus in vulnerable Himalayan snow trout, S. richardsonii.

中文翻译：

---

在易受伤害的喜马拉雅雪鳟鱼 Schizothorax richardsonii (Gray 1832) 中 Argulus japonicus (Thiele 1900) 的形态计量学和分子鉴定

Argulus是一种甲壳类鳃类寄生虫，在全世界的水产养殖中造成严重问题。通常，Argulus spp。通过形态学描述来识别。近年来，聚合酶链反应扩增与核糖体 RNA 序列结合形态描述正在成为Argulus spp物种水平鉴定的标准。本研究调查了Argulus sp。在雪鳟鱼中，Schizothorax richardsonii，使用形态学和分子工具。形态学上，该寄生虫的甲壳背脊分枝，前呼吸区呈棒状，后呼吸区呈弧形，3颗相对锋利的牙齿和第四游泳附肢上的几丁质铲钉。雌性Argulus sp. 它们的长度和宽度都比雄性大。形态特征和18s rRNA研究表明，寄生虫种类为Argulus japonicus。构建系统发育树来检查这些A之间的关系。 粳稻序列和现有的存档序列。在背鳍中观察到致病性 argulid 的最大分布，其次是腹鳍和胸鳍。本研究有助于第一物种级形态学和分子鉴定甲。 japonicus in 易受伤害的喜马拉雅雪鳟鱼，S。 richardsonii。