Eustrongylides sp. (Nematoda, Dioctophymatoidea) parasitizing Hoplias malabaricus (Actinopterygii: Erythrinidae) collected from the state of Rio de Janeiro, Brazil

Abstract Hoplias malabaricus (Characiformes, Erythrinidae), trahira, is a neotropical freshwater fish of economic and public health significance. A total of 45 specimens of H. malabaricus commercialized in the municipality of Magé, state of Rio de Janeiro, Brazil, were acquired between April 2016 and April 2018 to investigate the presence of nematode larvae. Twenty of the fish were found parasitized by 347 fourth-stage nematode larvae identified taxonomically as Eustrongylides sp. using morphological, morphometric and molecular data. The parasitic indices were: prevalence 44.44%, mean intensity 17.35, mean abundance 7.71, and range of infection 2-40. Infection sites were musculature, mesentery, abdominal cavity, and serosa of intestine, stomach and liver. This is the first report of Eustrongylides sp. larvae parasitizing H. malabaricus in the state of Rio de Janeiro.

摘要：花斑狼脂鲤（Hoplias malabaricus，隶属脂鲤目（Characiformes）、虎脂鲤科（Erythrinidae），俗称特拉伊拉鱼）是一类兼具经济与公共卫生价值的新热带淡水鱼类。本研究于2016年4月至2018年4月间，在巴西里约热内卢州马热市收购45尾市售该物种个体，以调查其线虫幼虫感染情况。检测发现，其中20尾鱼感染了347株线虫第四期幼虫；结合形态学、形态测量学与分子生物学数据，该幼虫被鉴定为恩斯特线虫属（Eustrongylides）未定种。本研究测得的寄生虫学指标如下：感染率44.44%，平均感染强度17.35，平均感染丰度7.71，感染范围为2~40。该幼虫的感染部位涵盖肌肉组织、肠系膜、腹腔，以及肠、胃与肝脏的浆膜层。本研究为里约热内卢州内首次报道恩斯特线虫属（Eustrongylides sp.）幼虫寄生于花斑狼脂鲤（Hoplias malabaricus）的案例。