1 1Department of Cellular Animal Physiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
2 2Department of Cellular Animal Physiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
3 3Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands; National Museum of Natural History Naturalis,
P.O. Box 9517, 2300 RA Leiden, The Netherlands
Flabellina cerverai sp. nov. was found in Bay La Herradura, Coquimbo, North of Chile, and clearly differs from other members of the Flabellinidae by the following combination of main characters: (1) small body size (4.5-6.3 mm), (2) translucent-yellow body coloration, with a white line along the dorsum and orange cerata, (3) rugose rhinophores, (4) anus located laterally in the anterior half of the body, (5) cerata distributed in 5 clusters with one additional ceras at the body end, (6) cerata low pedunculate, (7) radula formula 13 × (1:1:1), (8) rachidian teeth with thin and low apices, and (9) bilobed seminal receptacle in combination with a bursa copulatrix. The morphology, anatomy, histology and egg mass of this new species have been described. Special attention is given to the reproductive and central nervous system. Phylogenetic analysis shows that F. cerverai belongs to the most apomorphic Flabellinidae, with as closest relative, F. marcusorum, from which it differs in four main apomorphic characters.