Olson P D, Cribb T H, Tkach V V, Bray R A, Littlewood D T J
Parasitic Worms Division, Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
Int J Parasitol. 2003 Jul;33(7):733-55. doi: 10.1016/s0020-7519(03)00049-3.
Complete small subunit ribosomal RNA gene (ssrDNA) and partial (D1-D3) large subunit ribosomal RNA gene (lsrDNA) sequences were used to estimate the phylogeny of the Digenea via maximum parsimony and Bayesian inference. Here we contribute 80 new ssrDNA and 124 new lsrDNA sequences. Fully complementary data sets of the two genes were assembled from newly generated and previously published sequences and comprised 163 digenean taxa representing 77 nominal families and seven aspidogastrean outgroup taxa representing three families. Analyses were conducted on the genes independently as well as combined and separate analyses including only the higher plagiorchiidan taxa were performed using a reduced-taxon alignment including additional characters that could not be otherwise unambiguously aligned. The combined data analyses yielded the most strongly supported results and differences between the two methods of analysis were primarily in their degree of resolution. The Bayesian analysis including all taxa and characters, and incorporating a model of nucleotide substitution (general-time-reversible with among-site rate heterogeneity), was considered the best estimate of the phylogeny and was used to evaluate their classification and evolution. In broad terms, the Digenea forms a dichotomy that is split between a lineage leading to the Brachylaimoidea, Diplostomoidea and Schistosomatoidea (collectively the Diplostomida nomen novum (nom. nov.)) and the remainder of the Digenea (the Plagiorchiida), in which the Bivesiculata nom. nov. and Transversotremata nom. nov. form the two most basal lineages, followed by the Hemiurata. The remainder of the Plagiorchiida forms a large number of independent lineages leading to the crown clade Xiphidiata nom. nov. that comprises the Allocreadioidea, Gorgoderoidea, Microphalloidea and Plagiorchioidea, which are united by the presence of a penetrating stylet in their cercariae. Although a majority of families and to a lesser degree, superfamilies are supported as currently defined, the traditional divisions of the Echinostomida, Plagiorchiida and Strigeida were found to comprise non-natural assemblages. Therefore, the membership of established higher taxa are emended, new taxa erected and a revised, phylogenetically based classification proposed and discussed in light of ontogeny, morphology and taxonomic history.
完整的小亚基核糖体RNA基因（ssrDNA）和部分（D1 - D3）大亚基核糖体RNA基因（lsrDNA）序列被用于通过最大简约法和贝叶斯推断来估计复殖吸虫的系统发育。在此，我们贡献了80个新的ssrDNA序列和124个新的lsrDNA序列。从新生成的和先前发表的序列中组装了两个基因的完全互补数据集，包括代表77个命名科的163个复殖吸虫分类单元以及代表3个科的7个盾腹吸虫外类群分类单元。对这些基因进行了独立分析以及联合分析，并且使用包含其他无法明确比对的特征的简化分类单元比对，对仅包括较高等斜睾目分类单元进行了单独分析。联合数据分析产生了支持力度最强的结果，两种分析方法之间的差异主要在于它们的分辨率程度。包含所有分类单元和特征，并纳入核苷酸替代模型（具有位点间速率异质性的一般时间可逆模型）的贝叶斯分析被认为是系统发育的最佳估计，并用于评估它们的分类和进化。从广义上讲，复殖吸虫形成了一个二分法，分为导致短咽吸虫总科、双口吸虫总科和血吸虫总科（统称为双口吸虫目新名（nom. nov.））的一个谱系和复殖吸虫的其余部分（斜睾目），其中双泡吸虫目新名和横裂吸虫目新名形成两个最基部的谱系，其次是半尾吸虫目。斜睾目的其余部分形成了大量独立的谱系，通向包含异肉吸虫总科、戈德吸虫总科、微口吸虫总科和斜睾吸虫总科的冠群剑尾吸虫目新名，它们通过尾蚴中存在穿透型口针而联合在一起。尽管目前定义的大多数科以及在较小程度上的总科得到了支持，但发现棘口目、斜睾目和后睾目的传统分类包含非自然的组合。因此，对已确立的高级分类单元的成员进行了修订，建立了新的分类单元，并根据个体发育、形态学和分类历史提出并讨论了一个基于系统发育的修订分类。
