Shoop W L
Merck Institute for Therapeutic Research, Rahway, New Jersey 07065-0900.
J Parasitol. 1989 Feb;75(1):21-32.
A systematic analysis of the genera in the Diplostomidae and Strigeidae was made using the Proterodiplostomidae as the outgroup. The Proterodiplostomidae was the family with the greatest preponderance of primitive characters and its monophyly was supported by the unique paraprostate gland. However, no character state supported the monophyly of the Diplostomidae sensu Dubois, 1970. That paraphyletic taxon was composed of 3 monophyletic groups: the pseudosuckerless Neodiplostomidae n. fam. had the most primitive character states of the 3 and its monophyly was based on characters in the neascus/neodiplostomulum metacercariae; the Bolbophoridae n. fam., with pseudosuckers, had its monophyly supported by characters present in the newly named prodiplostomulum metacercaria; and the emended Diplostomidae, also with pseudosuckers, had the most derived states and its monophyly was supported by characters present in the diplostomulum. The presence of pseudosuckers united the Bolbophoridae n. fam., the emended Diplostomidae, and the Strigeidae as a monophyletic assemblage. The Strigeidae had the most derived characters of these 3 taxa and its monophyly was supported by characters in the tetracotyle and the cup-shaped forebody and bilobed tribocytic organ of the adult. In general, the adult stages of these strigeoid families showed very conserved morphology and it was the metacercariae that possessed the innovations. The conserved adult morphology was typical of what one might expect if the intramolluscan stages were analyzed. Thus, the data were concordant with the view that the mollusc and vertebrate definitive host were the original hosts to the Digenea and that the second intermediate host and metacercaria were more recently intercalated. More specifically, the phylogeny of these groups suggested that ancestral bisegmented strigeoids originally infected reptiles, they subsequently radiated into birds with which they coevolved extensively, and on 5 separate occasions they radiated into mammals. The radiations into mammals were, by all available evidence, preceded by second intermediate host shifts from fish to amphibians.
以原双口科作为外类群，对双口科和裂体科的属进行了系统分析。原双口科是具有最多原始特征的科，其单系性由独特的副前列腺腺支持。然而，没有特征状态支持杜布瓦（1970年）意义上的双口科的单系性。那个并系分类单元由3个单系类群组成：无伪吸盘的新双口科新科，在这3个类群中具有最原始的特征状态，其单系性基于新囊蚴/新双口蚴后尾蚴的特征；有伪吸盘的泡双口科新科，其单系性由新命名的前双口蚴后尾蚴中的特征支持；以及修订后的双口科，也有伪吸盘，具有最衍生的状态，其单系性由双口蚴中的特征支持。伪吸盘的存在将泡双口科新科、修订后的双口科和裂体科联合为一个单系组合。裂体科在这3个分类单元中具有最衍生的特征，其单系性由成虫的四盘蚴、杯状前体和双叶三细胞器官中的特征支持。一般来说，这些裂体科的成虫阶段显示出非常保守的形态，而具有创新特征的是后尾蚴。如果对软体动物体内阶段进行分析，保守的成虫形态是人们可能预期的典型形态。因此，这些数据与以下观点一致，即软体动物和脊椎动物终末宿主是复殖吸虫的原始宿主，而第二中间宿主和后尾蚴是最近才插入进来的。更具体地说，这些类群的系统发育表明，祖先的双节裂体类最初感染爬行动物，随后辐射到鸟类并与它们广泛共同进化，并且在5个不同的场合辐射到哺乳动物。根据所有现有证据，在辐射到哺乳动物之前，第二中间宿主从鱼类转移到了两栖动物。
