What is convergent/homoplastic in Pogonophora?

ABSTRACT

Characters of Pogonophora, including Perviata (Frenulata and Scleronlinida) and Vestimentifera, are critically analysed and the characters re-evaluated with respect to their reliability in determining relationships with Annelida-Polychaeta in general and with Oweniidae in particular, as well as with Oligomera. In addition to several differentiations which possibly express parallelisms, only a few characters reflect trustworthy information based on the current state of knowledge. These, however, still include 'sets' of both Annelida-Polychaeta features and Oligomera features; despite the more recent trend to regard the Pogonophora as annelids, no unequivocal preference can be given as to which of these 'sets' is convergent/homoplastic. The intra-epithelial nervous system without true cerebral ganglia, typical of Epineuralia as well as Pogonophora and Oweniidae, is here considered to represent the paedomorphic peripheral-epidermal larval system of Gastroneuralia in contrast to the ganglionated gastroneural adult system.