Fraija-Fernández Natalia, Hernández-Hortelano Ana, Ahuir-Baraja Ana E, Raga Juan Antonio, Aznar Francisco Javier
Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, PO Box 22085, Valencia 46071, Spain.
Dis Aquat Organ. 2018 Jun 4;128(3):249-258. doi: 10.3354/dao03226.
Pennella balaenoptera is a mesoparasitic copepod that has been reported in at least 17 cetacean species. Subtle morphological differences in the first antennae of adult females have been used to discriminate this species from P. filosa, a species infecting fishes. Other morphological traits are unreliable because of their high plasticity, and no molecular data are available to confirm the taxonomic status of P. balaenoptera as an independent species. We found no consistent morphological differences of the first antennae between P. balaenoptera and P. filosa collected from cetaceans and fish in the western Mediterranean. Molecular data on the mitochondrial cytochrome oxidase subunit I failed to show reciprocal monophyly for the 2 species, and nucleotide divergence between them was low (mean ± SD [range]: 4.1 ± 0.006% [0.5-8.9]). Thus, P. balaenoptera and P. filosa are considered conspecific. We also obtained data on infection parameters of P. balaenoptera based on 450 individuals of 6 cetacean species stranded on the Spanish Mediterranean coast between 1980 and 2017. Prevalence was significantly lowest in the most coastal species, the bottlenose dolphin Tursiops truncatus (3.6%) and highest in the most oceanic species, Cuvier's beaked whale Ziphius cavirostris (100%). This suggests that the life cycle of P. balaenoptera is primarily oceanic. Interestingly, P. filosa also occurs in the oceanic realm infecting large fishes. This ecological similarity further supports the hypothesis that P. balaenoptera and P. filosa are conspecific.
须鲸佩氏桡足虫是一种中寄生性桡足类动物，已在至少17种鲸类动物中被发现。成年雌性第一触角的细微形态差异已被用于将该物种与感染鱼类的丝状佩氏桡足虫区分开来。由于其他形态特征具有高度可塑性，因此不可靠，并且没有分子数据可用于确认须鲸佩氏桡足虫作为独立物种的分类地位。我们发现，在地中海西部从鲸类动物和鱼类采集的须鲸佩氏桡足虫和丝状佩氏桡足虫之间，第一触角没有一致的形态差异。线粒体细胞色素氧化酶亚基I的分子数据未能显示这两个物种的相互单系性，并且它们之间的核苷酸差异很低（平均值±标准差[范围]：4.1±0.006%[0.5-8.9]）。因此，须鲸佩氏桡足虫和丝状佩氏桡足虫被认为是同种的。我们还获得了基于1980年至2017年间搁浅在西班牙地中海沿岸的6种鲸类动物的450个个体的须鲸佩氏桡足虫感染参数数据。在最靠近海岸的物种宽吻海豚短吻真海豚中，患病率显著最低（3.6%），而在最海洋性的物种柯氏喙鲸中最高（100%）。这表明须鲸佩氏桡足虫的生命周期主要在海洋中。有趣的是，丝状佩氏桡足虫也出现在海洋区域感染大型鱼类。这种生态相似性进一步支持了须鲸佩氏桡足虫和丝状佩氏桡足虫是同种的假设。
