Nile tilapia, one of the most popular aquaculture species worldwide, has been introduced into the Congo Basin several times for aquaculture purposes. Previous studies based on morphological features showed that some of the monogenean gill parasites were co-introduced with Nile tilapia and some spilled over to native Congolese cichlids. In this study, we genetically investigated the co-introduced monogeneans of Nile tilapia from three major parts of the Congo Basin: Upper, Middle and Lower Congo. We sequenced 214 specimens belonging to 16 species of Monogenea, collected from native and introduced tilapia species from Congo, Madagascar and Burundi. We evaluate their position in a phylogeny including 38 monogenean species in total. Our results confirm the co-introductions in the Congo Basin and suggest one unreported parasite transmission from introduced Nile tilapia to native Mweru tilapia in Upper Congo, which was undetectable with a morphological study alone. Shared parasite COI haplotypes between Madagascar and the Congo Basin illustrate how anthropogenic introduction events homogenize parasite communities across large geographical distances and thereby disrupt isolation by distance patterns. Contrary to our expectation, the parasite populations co-introduced in the Congo Basin reveal a high COI diversity, probably resulting from multiple Nile tilapia introductions from different geographic origins. Additionally, we tested the barcoding gap and the performance of mitochondrial COI and nuclear ribosomal ITS-1, 28S and 18S markers. We found a significant barcoding gap of 15% for COI, but none for the other markers. Our molecular results reveal that Cichlidogyrus halli, C. papernastrema, C. tiberianus, C. cirratus and C. zambezensis are in need of taxonomic revision.

尼罗罗非鱼是世界上最受欢迎的水产养殖品种之一，已多次被引入刚果盆地用于水产养殖。先前基于形态特征的研究表明，一些单基因鳃寄生虫是与尼罗罗非鱼共同引入的，有些则溢出到当地的刚果慈鲷中。在这项研究中，我们对刚果盆地的三个主要部分：上刚果、中刚果和下刚果共同引入的尼罗罗非鱼单系生物进行了基因研究。我们对属于 16 种 Monogenea 的 214 个标本进行了测序，这些标本来自刚果、马达加斯加和布隆迪的本地和引进的罗非鱼物种。我们评估了它们在系统发育中的位置，总共包括 38 个单基因物种。我们的研究结果证实了刚果盆地的共同引入，并表明从引入的尼罗罗非鱼到上刚果的本地 Mweru 罗非鱼的一种未报告的寄生虫传播，仅通过形态学研究是无法检测到的。马达加斯加和刚果盆地之间共享的寄生虫 COI 单倍型说明了人为引入事件如何在大地理距离上使寄生虫群落同质化，从而破坏距离模式的隔离。与我们的预期相反，刚果盆地共同引入的寄生虫种群显示出较高的 COI 多样性，这可能是由于从不同地理来源引入的多种尼罗罗非鱼所致。此外，我们测试了条形码间隙以及线粒体 COI 和核核糖体 ITS-1、28S 和 18S 标记的性能。我们发现 COI 存在 15% 的显着条形码差距，但其他标记则没有。我们的分子结果表明Cichlidogyrus halli、C. papernastrema、C. tiberianus、C. cirratus和C. zambezensis需要进行分类修订。