Acanthocephalan parasites of the flounder species Paralichthys isosceles, Paralichthys patagonicus and Xystreurys rasile from Brazil

Abstract Flounders are commercially and economically important fish. A total of 120 specimens of flounders (60 Paralichthys isosceles, 30 Paralichthys patagonicus and 30 Xystreurys rasile) were collected off the coast of the state of Rio de Janeiro, Brazil. The fish were measured, necropsied and filleted, and then had their organs investigated for acanthocephalans. Taxonomic identification of the parasites was based on morphological, morphometric and genetic characters. Paralichthys isosceles and P. patagonicus were parasitized by juveniles of Serrasentis sagittifer, Bolbosoma turbinella, Corynosoma australe and C. cetaceum; Xystreurys rasile was parasitized by C. australe. Genetic characterization confirmed the identification of specimens of Bolbosoma turbinella and Corynosoma australe, as demonstrated by phylogenetic analyses using both ITS and cox1 molecular targets. Parasite indices of prevalence, intensity, mean intensity, abundance, mean abundance, and range of infection, as well as infection site, were evaluated for each parasite species. This is the first report of S. sagittifer parasitizing P. isosceles and P. patagonicus, and B. turbinella parasitizing P. patagonicus.

摘要：比目鱼是兼具商业与经济价值的重要鱼类。本研究共采集120尾比目鱼标本，其中等颌牙鲆（Paralichthys isosceles）60尾、巴塔哥尼亚牙鲆（Paralichthys patagonicus）30尾、斜纹长颌鲆（Xystreurys rasile）30尾，采集地点位于巴西里约热内卢州近岸海域。研究人员对所有受试比目鱼开展体长测量、尸体解剖与剔肉处理，随后对其各器官进行棘头虫（acanthocephalans）筛查。寄生虫的分类鉴定基于形态学、形态测量学及遗传学特征完成。等颌牙鲆与巴塔哥尼亚牙鲆均被箭形锯棘棘头虫（Serrasentis sagittifer）、小瘤球体棘头虫（Bolbosoma turbinella）、南方棘吻虫（Corynosoma australe）以及鲸棘吻虫（Corynosoma cetaceum）的幼虫寄生；斜纹长颌鲆仅被南方棘吻虫寄生。基于ITS与cox1两个分子标记的系统发育分析结果，证实了小瘤球体棘头虫与南方棘吻虫标本的分类鉴定结果。研究人员针对每种寄生虫，统计了感染率（prevalence）、感染强度（intensity）、平均感染强度（mean intensity）、感染丰度（abundance）、平均感染丰度（mean abundance）、感染范围（range of infection）以及感染部位（infection site）等寄生虫学指标。本研究为箭形锯棘棘头虫寄生于等颌牙鲆与巴塔哥尼亚牙鲆、以及小瘤球体棘头虫寄生于巴塔哥尼亚牙鲆的首次学术报道。