Di Azevedo Maria Isabel N, Knoff Marcelo, Carvalho Vitor L, Mello Wildon N, Lopes Torres Eduardo J, Gomes Delir C, Iñiguez Alena M
LABTRIP, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, 21045-900 RJ, Brazil.
Dis Aquat Organ. 2015 Mar 9;113(2):103-11. doi: 10.3354/dao02831.
Anisakid nematodes have been identified in a wide variety of fish and marine mammal species. In Brazil, Anisakis physeteris, A. insignis, A. typica, A. nascetti, and those of the A. simplex complex have been reported infecting fishes and cetaceans. In this study, specimens collected from a dwarf sperm whale Kogia sima (Owen, 1866) stranded on the northeastern coast of Brazil were identified through morphological and genetic analyses as A. paggiae. Anisakids were examined through differential interference contrast light and scanning electron microscopy (SEM). Morphological and morphometric analysis revealed that these specimens belonged to Anisakis sp. clade II and more specifically to A. paggiae, exhibiting a violin-shaped ventriculus and 3 denticulate caudal plates, which are taxonomic characters considered unique to this species. Genetic analysis based on the mtDNA cox2 gene confirmed our identification of A. paggiae. Phylogenetic trees using both maximum likelihood and neighbor-joining methods revealed a strongly supported monophyletic clade (bootstrap support = 100%) with all available A. paggiae sequences. Integrative taxonomic analysis allowed the identification of A. paggiae for the first time in Brazilian waters, providing new data about their geographical distribution. Moreover, here we present the first SEM images of this species.
异尖线虫已在多种鱼类和海洋哺乳动物物种中被鉴定出来。在巴西，已报道过抹香异尖线虫、标记异尖线虫、典型异尖线虫、纳氏异尖线虫以及简单异尖线虫复合体中的线虫感染鱼类和鲸类。在本研究中，通过形态学和遗传学分析，从搁浅在巴西东北海岸的一头侏儒抹香鲸（Kogia sima，欧文，1866年）身上采集的标本被鉴定为帕氏异尖线虫。通过微分干涉相差光镜和扫描电子显微镜（SEM）对异尖线虫进行了检查。形态学和形态测量分析表明，这些标本属于异尖线虫属进化枝II，更具体地说是帕氏异尖线虫，其具有小提琴形的胃和3个具齿的尾板，这些是该物种独有的分类特征。基于线粒体DNA细胞色素氧化酶亚基2（mtDNA cox2）基因的遗传分析证实了我们对帕氏异尖线虫的鉴定。使用最大似然法和邻接法构建的系统发育树显示，所有可用的帕氏异尖线虫序列形成了一个得到有力支持的单系进化枝（自展支持率 = 100%）。综合分类分析首次在巴西水域鉴定出帕氏异尖线虫，提供了关于其地理分布的新数据。此外，我们在此展示了该物种的首张扫描电子显微镜图像。
