Reconstructing the Phylogenetic Relationships of the Cyclophyllidean Cestodes: A Case Study Using ITS2 rDNA and Sequence-Structure Alignment

Different authors have subscribed to varied opinions on the phylogenetic relationships and systematic position of cyclophyllidean cestodes owing to high degree of non-significant morphological variations among these taxa. Molecular phylogenetic analysis based on ITS2 rDNA of 16 representatives spanning 6 different families (Mesocestoididae, Davaineidae, Anoplocephalidae, Taeniidae, Dipylidiidae and Hymenolepididae) of the Order Cyclophyllidea and one out group from the family Diphyllobothriidae of the Order Pseudophyllidea revealed the order Order Cyclophyllidea to be a monophyletic clade. The results were further validated by bayesian analysis, primary sequence-structure alignment and subsequent molecular morphometrics analysis. A consistent support for all the major nodes was seen across all the phylogenetic trees. Interestingly, the genus Mesocestoides, in which the genital pores are ventral in position, a feature of the Order Pseudophyllidea, was accommodated within Cyclophyllidea and served as a sister clade close to the families Taeniidae, Anoplocephalidae, Hymenolepididae and Dipylidiidae.