Steiner, T.M.; Amaral, A.C.Z. 2009. Arabella aracaensis, a new species with growth rings on its mandibles, and some remarks on the endoparasitic Labrorostratus prolificus (Polychaeta: Oenonidae) from southeast Brazil. Journal of Natural History 43(41-42): 2537-2551
The family Oenonidae is composed of 12 genera, some of which are exclusively parasitic in the body cavity of other polychaetes, as well as bivalves and echiurans. One of these is the genus Labrorostratus, with six described species. Labrorostratus prolificus Amaral, 1977 is known only from Brazil, as a parasite in the body cavity of Perinereis cultrifera (Grube, 1840), and in a species of Eunicidae. The genus Arabella has about 20 described species, three of which occur on the Brazilian coast. This study describes the first growth stages of L. prolificus, and adds new information to the original description. The new species Arabella aracaensis is described, with remarks on the presence of growth rings on its mandibles.