Molecular phylogeny of some polychaete annelids: An initial approach to the Atlantic-Mediterranean speciation problem

Summary The polychaete Eupolymnia nebulosa (family Terebellidae) displays two alternative modes of reproduction. In the Mediterranean, larvae are brooded in a mucous mass while in the Atlantic and English Channel, larvae follow a planktonic development. This paper attempts to discern whether this difference is expressed at the population, infraspecies, or species level. Specimens of E. nebulosa and representatives of a number of control species were sampled from Atlantic/English Channel and Mediterranean locations. Genetic sequencing of the Large-subunit ribosomal RNA 5 end of six representative species allowed one to infer the relative position of E. nebulosa within the Terebellidae and the position of the latter within the animal kingdom. The relative genetic distances calculated between the different species were also used to approach the speciation problem raised by the differences between the Mediterranean and Atlantic/English Channel population of E. nebulosa. The genetic distance between Mediterranean and Atlantic populations of both E. nebulosa and Lanice conchilega are of the same order, suggesting that differences between the populations of E. nebulosa are infraspecific. Offprint requests to: M. Bhaud     

On the anatomy of the central nervous system and the morphological value of the anterior end appendages of Ampharetidae, Pectinariidae and Terebellidae (Polychaeta)

Earlier papers dealing with the anatomy of the central nervous system of ampharetids, pectinariids and terebellids were studied. On this basis a re‐investigation appeared necessary: statements in the literature about the structure of the brain and the innervation of the appendages of the anterior end were incomplete and contradictory. In the present paper, the brain, the circum‐oesophageal connectives and the innervation of, inter alia, the tentacular membrane (including the dorsal ridge), the buccal tentacles, the alimentary canal, the nuchal organs and the branchiae (when present) of Amphicteis gunneri, Anobothrus gracilis, Melinna cf. cristata, Pectinaria auricoma, P. belgica, P. koreni, Petta pusilla, Pista cristata, Eupolymnia nebulosa, Thelepus cincinnatus and Polycirrus medusa are described. The results are summarized in schematic diagrams and compared with each other and with the central nervous system of other polychaetes. It is concluded that the ampharetids, the pectinariids and the terebellids bear no antennae and no palps and that their buccal tentacles belong to the alimentary canal. It is emphasized that all attempts to range their cephalic nervous system into previously proposed common and general schemes of ‘the polychaete nervous system’ seem totally fruitless.