Phylogeny and paraphyly among tetrapod blood flukes (Digenea: Schistosomatidae and Spirorchiidae).

摘要: The blood flukes of turtles (Digenea: Spirorchiidae) and the crocodilians, birds mammals Schistosomatidae) have long been considered as closely related, but distinct evolutionary lineages. Recent morphological molecular studies these families sister taxa within Schistosomatoidea. Representatives both similar furcocercous cercariae two-host life cycles, different definitive hosts, reproductive patterns morphologies. Sequences including approximately 1800 bases small subunit ribosomal DNA 1200 large were generated from representatives eight spirorchiid genera. These sequences aligned with pre-existing Schistosomatidae other Diplostomida analysed for phylogenetic signal using maximum parsimony Bayesian inference. analyses revealed that Spirorchiidae is paraphyletic turtle are basal to highly derived schistosomatids. Three genera spirorchiids marine form a group five freshwater occupy positions in phylogeny tetrapod flukes. Marine be results current study indicate parasites similarly ancestor. close relationship schistosomatids position transmitted Austrobilharzia Ornithobilharzia schistosomatid clade suggests arose after fluke ancestor successfully colonised birds.