A micro-CT approach to the anatomy of Pectinariidae Quatrefages, 1866 (Annelida)

The Micro-computed X-ray tomography (micro-CT) technique is used to examine the external and internal anatomy of four species of Pectinariidae (Annelida: Terebellida): Amphictene auricoma, Cistenides granulata, Cistenides hyperborea and Lagis sp., from material collected off Iceland and NW Spain. The main aims were: (1) to provide new and additional observations on pectinariid external and internal anatomy, (2) to test the usefulness and limitations of micro-CT against other techniques and 3) to explore for characters with potential taxonomic value to be studied in the future. Micro-CT provided good images of several external relevant taxonomic characters such as paleae, cephalic veil, scaphe, scaphal hooks and anal lobe, but was especially useful for the examination of internal anatomy. The best visualized organs were those of higher tissue density (i.e. body musculature, digestive tract, main blood vessel, glands), whereas less electrodense tissues (i.e. peritoneal lining/septa, nephridia, nervous system) were less evident. Images of internal organs showed heterogeneous results: micro-CT may serve well to assess regionalization of digestive system and its variability across taxa, together with musculature and glands, while images of circulatory and nervous systems only show good results in their more electrodense components (main blood vessels/heart and ventral nerve cord/brain, respectively).