Department of Parasitology, Laboratório de Biologia de Trematoda, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, P.O. Box 486, 30123-970, Belo Horizonte, Minas Gerais, Brazil.
Parasitology. 2022 Mar;149(3):325-336. doi: 10.1017/S0031182021001864. Epub 2021 Oct 28.
Although Echinostoma robustum (currently a synonym of E. miyagawai) was reported in the Americas based on molecular data, morphological support on adult parasites is still required. Herein, a new species of Echinostoma is described based on worms found in a chicken from Brazil. Molecular phylogenetic analyses based on 28S (1063 bp), ITS (947 bp) and Nad-1 (442 bp) datasets reveal the inclusion of the new species within Echinostoma ‘revolutum’ species complex. Moreover, it was verified the conspecificity between cercariae previously identified as E. robustum in Brazil [identical ITS and only 0.3% of divergence (1 nucleotide) in Nad-1]. Species discovery analyses show that these two isolates form an independent lineage (species) among Echinostoma spp. Compared to E. miyagawai, the new species presents relatively high divergence in Nad-1 (7.88–9.09%). Morphologically, the specimens are distinguished from all nominal species from the ‘revolutum’ species complex by the more posterior position of the testes (length of post-testicular field as a proportion of body length about 20%). They further differ from E. miyagawai and South American Echinostoma spp. by the higher proportion of forebody to the body length. Therefore, combined molecular and morphological evidence supports the proposal of the species named here as Echinostoma pseudorobustum sp. nov.
尽管基于分子数据已在美洲报道了 Echinostoma robustum（目前为 E. miyagawai 的同义词），但仍需要成虫寄生虫的形态学支持。在此，根据在巴西鸡中发现的蠕虫描述了一种新的 Echinostoma 物种。基于 28S（1063 bp）、ITS（947 bp）和 Nad-1（442 bp）数据集的分子系统发育分析表明，新物种包含在 Echinostoma‘revolutum’物种复合体中。此外，还验证了在巴西先前鉴定为 E. robustum 的尾蚴的同物异性（ITS 相同，Nad-1 仅相差 0.3%（1 个核苷酸））。物种发现分析表明，这两个分离株在 Echinostoma spp. 中形成了一个独立的谱系（物种）。与 E. miyagawai 相比，新物种在 Nad-1 中表现出相对较高的分化（7.88-9.09%）。形态上，这些标本与“revolutum”物种复合体中的所有命名种都有所不同，因为睾丸的位置更靠后（后睾丸区的长度占体长的比例约为 20%）。它们还与 E. miyagawai 和南美洲的 Echinostoma spp. 不同，因为前体与体长的比例更高。因此，分子和形态学证据的综合支持了这里提出的将该物种命名为 Echinostoma pseudorobustum sp. nov. 的建议。
