Institute for Parasitology and Tropical Veterinary Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
CIISA - Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal.
Sci Rep. 2021 Apr 15;11(1):8245. doi: 10.1038/s41598-021-87500-8.
Cyathostomins are important intestinal nematode parasites of equines and include 50 accepted species. Their taxonomy has been frequently revised and the presence of cryptic species suggested. Furthermore, usually molecular- and morphology-based phylogenetic analyses give divergent results. In this study, the nucleotide sequences of the nuclear second internal transcribed spacer (ITS-2) and the mitochondrial partial cytochrome c oxidase subunit I (COI) were determined for adults of six cyathostomin species (Coronocyclus coronatus, Coronocyclus labiatus, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus longibursatus, Cylicostephanus minutus) collected from different equine species within two geographic regions. Maximum likelihood trees were calculated for ITS-2, COI, and concatenated data. No obvious differentiation was observed between geographic regions or equine host species. As previously reported, Coronocyclus coronatus and Cylicostephanus calicatus revealed a close relationship. Cryptic species were detected in Cylicostephanus minutus and Cylicostephanus calicatus. Cylicocyclus nassatus and Coronocyclus labiatus showed diverse mitochondrial and nuclear haplotypes occurring in different combinations, while Cylicostephanus longibursatus was comparatively homogenous. In conclusion, a combined analysis of nuclear and mitochondrial haplotypes improved resolution of the phylogeny and should be applied to the remaining cyathostomin species and across additional equine host species and geographic regions.
Cyathostomins 是马属动物重要的肠道寄生线虫，包括 50 个已被接受的种。其分类学经常被修订，并暗示存在隐种。此外，通常基于分子和形态的系统发育分析会给出不同的结果。在这项研究中，确定了从两个地理区域的不同马属动物中采集的六种 Cyathostomin 成虫的核第二内部转录间隔区（ITS-2）和线粒体部分细胞色素 c 氧化酶亚基 I（COI）的核苷酸序列。为 ITS-2、COI 和串联数据计算了最大似然树。未观察到地理区域或马属宿主种之间的明显分化。如先前报道的那样，Coronocyclus coronatus 和 Cylicostephanus calicatus 显示出密切的关系。在 Cylicostephanus minutus 和 Cylicostephanus calicatus 中检测到隐种。Cylicocyclus nassatus 和 Coronocyclus labiatus 显示出不同组合的多样化线粒体和核单倍型，而 Cylicostephanus longibursatus 则相对同质。总之，核和线粒体单倍型的联合分析提高了系统发育的分辨率，应应用于剩余的 Cyathostomin 种以及其他马属宿主种和地理区域。
