FAUCHALD, K.: Facial tubercles in scale worms (Aphroditacea; Polychaeta; Annelida)

The most obvious synapomorphy for the aphroditacean polychaetes are the flattened scales on the dorsum. However, many scale worms have facial tubercles; this may be another structure unique to the scale worms. As the term is used now, facial tubercles include a variety of anterior structures located ventrally between the posterior edge of the prostomium and the frontal edge of the eversible pharynx. In the current paper these structures are characterized and a cursory survey of the distribution of the different components among the scale worms is presented. The results suggests that a detailed anatomical study of these features is likely to yield interesting results.