THE EVIDENCE FROM PARASITE RELATIONSHIPS FOR THE EVOLUTIONARY STATUS OF XENOPUS (ANURA PIPIDAE)

Abstract

SUMMARY The Pipidae are generally considered a relatively early offshoot in anuran evolution but a recent review, based mainly on nerve ganglia characteristics, has concluded that the group is not primitive by any criteria. Consideration of parasite phylogenetic relationships provides another, independent, view of pipid status. The parasite fauna of Xenopus is highly distinctive and displays a mixture of primitive and very specialised characters. Detailed analysis of one group— the monogeneans— suggests that Protopolystoma, infecting Xenopus, is primitive and very distant with respect to polystomatids in advanced anurans including ranids and bufonids. The combined evidence of a range of invertebrate groups indicates that parasite affinities are best interpreted as a product of prolonged phylogenetic and ecological isolation of the host. It is concluded that pipids are archaic and cannot be aligned with advanced families.