Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic.
Parasit Vectors. 2013 Mar 13;6:64. doi: 10.1186/1756-3305-6-64.
The digenean species of Echinostoma (Echinostomatidae) with 37 collar spines that comprise the so-called 'revolutum' species complex, qualify as cryptic due to the interspecific homogeneity of characters used to differentiate species. Only five species were considered valid in the most recent revision of the group but recent molecular studies have demonstrated a higher diversity within the group. In a study of the digeneans parasitising molluscs in central and northern Europe we found that Radix auricularia, R. peregra and Stagnicola palustris were infected with larval stages of two cryptic species of the 'revolutum' complex, one resembling E. revolutum and one undescribed species, Echinostoma sp. IG. This paper provides morphological and molecular evidence for their delimitation.
Totals of 2,030 R. auricularia, 357 R. peregra and 577 S. palustris were collected in seven reservoirs of the River Ruhr catchment area in Germany and a total of 573 R. peregra was collected in five lakes in Iceland. Cercariae were examined and identified live and fixed in molecular grade ethanol for DNA isolation and in hot/cold 4% formaldehyde solution for obtaining measurements from fixed materials. Partial fragments of the mitochondrial gene nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) were amplified for 14 isolates.
Detailed examination of cercarial morphology allowed us to differentiate the cercariae of the two Echinostoma spp. of the 'revolutum' species complex. A total of 14 partial nad1 sequences was generated and aligned with selected published sequences for eight species of the 'revolutum' species complex. Both NJ and BI analyses resulted in consensus trees with similar topologies in which the isolates from Europe formed strongly supported reciprocally monophyletic lineages. The analyses also provided evidence that North American isolates identified as E. revolutum represent another cryptic species of the 'revolutum' species complex.
Our findings highlight the need for further analyses of patterns of interspecific variation based on molecular and morphological evidence to enhance the re-evaluation of the species and advance our understanding of the relationships within the 'revolutum' group of Echinostoma.
具有 37 个领环刺的吸虫属 Echinostoma（Echinostomatidae）物种，构成了所谓的“ revolutum”物种复合体，由于用于区分物种的种间同质性而成为隐种。在该组最近的修订中，仅认为有五个种是有效的，但最近的分子研究表明该组内具有更高的多样性。在一项研究中，我们发现寄生在中欧和北欧软体动物中的吸虫耳萝卜螺、苍白萝卜螺和沼泽萝卜螺被“ revolutum”复合体的两个隐种的幼虫阶段感染，一个类似于 E. revolutum，另一个为未描述的种，Echinostoma sp. IG。本文提供了其界限的形态学和分子证据。
总共从德国鲁尔河集水区的七个水库中收集了 2030 只耳萝卜螺、357 只苍白萝卜螺和 577 只沼泽萝卜螺，总共从冰岛的五个湖泊中收集了 573 只苍白萝卜螺。通过活体检视和鉴定尾蚴，并将其固定在分子级乙醇中用于 DNA 分离，以及在热/冷 4％甲醛溶液中固定材料以获得测量值。为 14 个分离株扩增了线粒体基因烟酰胺腺嘌呤二核苷酸脱氢酶亚单位 1（nad1）的部分片段。
对尾蚴形态的详细检查使我们能够区分“ revolutum”物种复合体的两种 Echinostoma 尾蚴。总共生成了 14 个部分 nad1 序列，并与“ revolutum”物种复合体的八个种的选定已发表序列进行了比对。NJ 和 BI 分析均产生了具有相似拓扑结构的共识树，其中来自欧洲的分离株形成了强烈支持的相互单系群。分析还提供了证据，表明北美鉴定为 E. revolutum 的分离株代表了“ revolutum”物种复合体的另一个隐种。
我们的发现强调需要进一步分析基于分子和形态学证据的种间变异模式，以增强对物种的重新评估，并增进对“ revolutum”组内 Echinostoma 关系的理解。
