Gonchar Anna, Jouet Damien, Skírnisson Karl, Krupenko Darya, Galaktionov Kirill V
Department of Invertebrate Zoology, St Petersburg State University, Universitetskaya emb. 7-9, St Petersburg, Russia, 199034.
EA7506-Biospectroscopie Translationnelle (BioSpecT), Université de Reims Champagne-Ardenne, Villa Douce, 9 bd de la Paix, 51097, Reims cedex, France.
Parasitol Res. 2019 May;118(5):1445-1456. doi: 10.1007/s00436-019-06297-8. Epub 2019 Mar 28.
Digenean parasites feature a series of stages with a distinct appearance, reproduction mode, and lifestyle that together constitute their well-known, complex life cycle. Species descriptions of Digenea have always been based on one of these stages-the marita, or sexually reproducing adult in the final host. However, in some cases, data on the life cycle are essential for the differential diagnosis of closely related species. Here, we present the case of Notocotylus atlanticus, where different stages of its life cycle were discovered for the first time since the species description, and across the Atlantic. We used a material from a naturally infected intertidal marine snail, Ecrobia ventrosa, and several waterfowl species and also carried out infection experiments. For morphological studies, we employed light microscopy, SEM, and CLSM; molecular data obtained include sequences of ITS1 and 28S rRNA gene. We demonstrate that N. atlanticus adult worm morphology is barely sufficient to distinguish it from several other species. Cercariae morphology and identity of the first intermediate hosts provide crucial additional information. According to our preliminary phylogenetic reconstructions, two notocotylid lineages are associated with two major gastropod lineages-the Caenogastropoda and the Heterobranchia. The traditional character to identify notocotylid genera (structure of ventral organs) fails to explain the phylogeny and thus requires reassessment. Further reliable morphological, life cycle and molecular data on other species are likely to reveal more patterns in notocotylid systematics, host specificity, and evolution.
复殖吸虫具有一系列不同形态、繁殖方式和生活方式的阶段，这些阶段共同构成了它们广为人知的复杂生命周期。复殖吸虫的物种描述一直基于这些阶段之一——成虫，即在终末宿主体内进行有性繁殖的阶段。然而，在某些情况下，生命周期数据对于密切相关物种的鉴别诊断至关重要。在此，我们介绍大西洋背孔吸虫的案例，自该物种被描述以来，首次在大西洋彼岸发现了其生命周期的不同阶段。我们使用了来自自然感染的潮间带海洋蜗牛——泡状织纹螺以及几种水鸟的样本，还进行了感染实验。对于形态学研究，我们采用了光学显微镜、扫描电子显微镜和共聚焦激光扫描显微镜；获得的分子数据包括ITS1和28S rRNA基因序列。我们证明，大西洋背孔吸虫成虫的形态几乎不足以将其与其他几个物种区分开来。尾蚴形态和第一中间宿主的身份提供了至关重要的额外信息。根据我们初步的系统发育重建，两个背孔科谱系与两个主要的腹足纲谱系——新腹足目和异鳃亚纲相关联。用于鉴定背孔科属的传统特征（腹侧器官的结构）无法解释系统发育，因此需要重新评估。关于其他物种的进一步可靠的形态学、生命周期和分子数据可能会揭示背孔科系统学、宿主特异性和进化方面的更多模式。
