Montes M M, Castro-Romero R, Martorelli S R
Centro de Estudios Parasitológicos y Vectores (CEPAVE), Consejo Nacional del Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata (CCT-La Plata CONICET-UNLP), Calle 120 s/n e/60 y 64, 1900, La Plata, Buenos Aires, Argentina.
Universidad de Antofagasta, Facultad de Ciencias del Mar y recursos naturales, Departamento de Ciencias Acuáticas y Ambientales, Casilla 170, Antofagasta, Chile.
Acta Trop. 2017 Sep;173:34-44. doi: 10.1016/j.actatropica.2017.05.025. Epub 2017 May 22.
We present a detailed morphological description and a DNA barcoding of Parabrachiella platensis n. sp. collected from Mugil liza Valenciennes in Samborombon Bay (Buenos Aires, Argentina). This new species was compared with two Parabrachiella species parasitic on mugilids: Parabrachiella exilis (Shiino, 1956) and Parabrachiella mugilis (Kabata, Raibaut et Ben Hassine, 1971). Parabrachiella platensis n. sp. differs from those species in the shape of posterior processes, the anal slit with two pairs of bipartite papillae, the size of cephalothorax, the trunk, the maxilla, the microhabitat on the host, and the lack of caudal rami. On the host, the new species was in the nostrils (a new site for a species of the genus Parabrachiella) and in the fins base. Some minor morphological differences were observed in relation to the locations on the host. The molecular analysis conducted based on mtDNA-COI between specimens of the new species on the fins and nostrils showed a genetic similarity of 99.8%. This percentage supports that the specimens found in nostrils and fins base could represent a single species. New studies on P. platensis n. sp., including infection of the same fish with the two forms, could bring some new information. Anyway according to the genetic information provided and the minimal morphological differences spotted we conclude that the two forms are a single specie. The differences observed are possibly influenced by the place of the host where the two forms of copepods were found, nostrils and fins. The new species was also molecularly compared to other five species of Parabrachiella including P. exilis (parasitizing mugilid from Chile), Parabrachiella anisotremis, Parabrachiella auriculata, Parabrachiella merluccii, and P. hugu (the last two sequences were taken from the GenBank). The genetic distance of 9% among P. platensis n. sp. and P. exilis, which is the close morphological related species, allow to states that these two copepods on mugilids belong to different species and then validating the morphological differences found between them.
我们对采自阿根廷布宜诺斯艾利斯省桑博龙湾的瓦伦西亚丽脂鲤（Mugil liza Valenciennes）的普拉滕斯副臂尾桡足虫（Parabrachiella platensis n. sp.）进行了详细的形态学描述和DNA条形码分析。将这个新物种与寄生于丽脂鲤科鱼类的另外两种副臂尾桡足虫进行了比较：微小副臂尾桡足虫（Parabrachiella exilis，椎野，1956年）和丽脂鲤副臂尾桡足虫（Parabrachiella mugilis，卡巴塔、雷鲍特和本·哈西内，1971年）。普拉滕斯副臂尾桡足虫新种在尾突形状、具两对二分乳头的肛裂、头胸部大小、躯干部、上颌、宿主上的微生境以及无尾叉等方面与上述物种不同。在宿主上，新物种寄生于鼻孔（副臂尾桡足虫属一个物种的新寄生部位）和鳍基部。在宿主不同部位观察到一些细微的形态差异。基于线粒体DNA细胞色素氧化酶亚基I（mtDNA-COI）对鳍部和鼻孔处的新物种标本进行的分子分析显示，其遗传相似度为99.8%。这一百分比支持在鼻孔和鳍基部发现的标本可能代表单一物种。对普拉滕斯副臂尾桡足虫新种的进一步研究，包括用两种形态感染同一条鱼，可能会带来一些新信息。无论如何，根据所提供的遗传信息以及发现的最小形态差异，我们得出结论，这两种形态属于单一物种。观察到的差异可能受宿主上发现这两种桡足类形态的部位（鼻孔和鳍）的影响。还将新物种与其他五种副臂尾桡足虫进行了分子比较，包括微小副臂尾桡足虫（寄生于智利丽脂鲤科鱼类）、异形副臂尾桡足虫（Parabrachiella anisotremis）、耳状副臂尾桡足虫（Parabrachiella auriculata）、无须鳕副臂尾桡足虫（Parabrachiella merluccii）和胡古副臂尾桡足虫（P. hugu，后两个序列取自基因库）。普拉滕斯副臂尾桡足虫新种与形态上相近的微小副臂尾桡足虫之间9%的遗传距离表明，这两种寄生于丽脂鲤科鱼类的桡足类属于不同物种，从而验证了它们之间发现的形态差异。
