Machkewskyi Volodymyr K, Dmitrieva Evgenija V, Gibson David I, Al-Jufaili Sara
Laboratory of Parasitology, Fishery Quality Control Centre, Ministry of Agriculture and Fisheries Wealth of Sultanate of Oman, P.O. Box: 427, Muscat, 100, Sultanate of Oman.
Syst Parasitol. 2014 Nov;89(3):215-36. doi: 10.1007/s11230-014-9522-3. Epub 2014 Oct 10.
Specimens of Lamellodiscus Johnston & Tiegs, 1922 (Monogenea: Diplectanidae) were collected from the gills of Cheimerius nufar (Valenciennes) (Sparidae) in the Arabian Sea. All of these parasites belonged to one and the same species, which is morphologically very close to L. euzeti Diamanka, Boudaya, Toguebaye & Pariselle, 2011. A different host, distant locality and small morphological differences compared with the original description of L. euzeti acted as a stimulus for a detailed redescription. The specimens from the Arabian Sea differ slightly in the details of the male copulatory organ (MCO) from the type-specimens of L. euzeti, which were re-examined, and from the respective drawings in its original description. Such differences include a longer inner process of the large element of the accessory piece associated with the proximal part of the copulatory tube, a longer point on the small element of the accessory piece associated with the distal part of the copulatory tube, and the presence of a smooth or slightly folded inner margin of this element rather than structures resembling spines which occur in the type-specimens of L. euzeti. Therefore, the present specimens infecting C. nufar in the Indo-Pacific may represent a different, but morphologically very similar species to the Atlantic form L. euzeti; consequently, they are recognised here as Lamellodiscus aff. euzeti. This form belongs to the 'ignoratus s. str.' subgroup of the genus. The composition of this subgroup is redefined to comprise 17 species, including L. corallinus Paperna, 1965 but excluding L. acanthopagri Roubal, 1981, and the morphology of the MCO of representatives of this group is clarified. A link between the diversity of Lamellodiscus species and the ancestral origin of present-day sparid species in the Tethys Sea is suggested. It is shown that Lamellodiscus spp. exhibit rather high levels of specificity to their hosts, since half of them parasitise only a single host species and c.90% infect closely related host species. Comparison of the levels of host-specificity of the species of this genus with other narrowly specific genera of the Dactylogyridea revealed that their estimations are comparable. The possibility of intra-host speciation within Lamellodiscus is discussed. It is shown that a co-evolutionary model is more discernible if it includes data on the occurrence of morphologically similar species from different regions and host taxa.
2022年从阿拉伯海的纳氏羊鲷（瓦朗谢纳）（鲷科）鳃上采集到了约翰斯顿和蒂格斯于1922年命名的片盘虫属（单殖吸虫纲：双盘吸虫科）标本。所有这些寄生虫都属于同一物种，在形态上与2011年的欧氏片盘虫非常接近。与欧氏片盘虫的原始描述相比，不同的宿主、遥远的产地以及微小的形态差异促使对其进行详细的重新描述。来自阿拉伯海的标本在雄性交配器官（MCO）的细节上与重新检查过的欧氏片盘虫模式标本以及原始描述中的相应绘图略有不同。这些差异包括与交配管近端相连的附属片大元件的内突较长，与交配管远端相连的附属片小元件上的尖端较长，以及该元件内缘是光滑的或略有褶皱，而非欧氏片盘虫模式标本中类似刺的结构。因此，目前在印度 - 太平洋地区感染纳氏羊鲷的这些标本可能代表了一个与大西洋的欧氏片盘虫不同但形态非常相似的物种；因此，在这里将它们识别为近似欧氏片盘虫。这种形态属于该属的“ignoratus狭义”亚组。重新定义了这个亚组的组成，包括1965年的珊瑚片盘虫，但不包括1981年的棘鲷片盘虫，并阐明了该组代表的MCO形态。有人提出片盘虫属物种的多样性与现今鲷科物种在特提斯海的祖先起源之间存在联系。研究表明，片盘虫属对其宿主表现出相当高的特异性水平，因为其中一半仅寄生于单一宿主物种，约90%感染亲缘关系密切的宿主物种。将该属物种的宿主特异性水平与指环虫目的其他狭义属进行比较后发现，它们的估计值具有可比性。文中还讨论了片盘虫属内宿主内物种形成的可能性。结果表明，如果共同进化模型纳入来自不同地区和宿主类群的形态相似物种的出现数据，那么这种模型会更明显。
