The genus Exogonoides Day, 1963, was described probably based on a single specimen, broken into two pieces (Aguado & San Martín 2008) and no other specimens of the type species, E. antennata Day, 1963, were ever found, which characterizes this species and, until now, the very genus Exogonoides, as ‘singletons’ (Lim et al. 2012). Although described as a member of the Syllidae Grube, 1850, the positioning of the genus in the family was recently questioned (Aguado & San Martín 2008), since the pharynx of the holotype was dissected for the original description and not preserved with the specimen, resulting that the presence of the proventricle, considered the main synapomorphy of the family, could not be confirmed.
Aguado, M.T. & San Martín, G. (2008) Re-description of some enigmatic genera of Syllidae (Phyllodocida: Polychaeta). Journal of the Marine Biological Association of the United Kingdom, 88, 35–56.
Briggs, J.C. & Bowen, B.W. (2013) Marine shelf habitat: biogeography and evolution. Journal of Biogeography, 40, 1023–1035.
Day, J.H. (1963) The polychaete fauna of South Africa part 8: new species and records from grab samples and dredgings. Bulletin of the British Museum (Natural History), 10, 383–445.
Dayrat, B. (2005) Towards integrative taxonomy. Biological Journal of the Linnean Society, 85, 407–415.
Fukuda, M.V. & Nogueira, J.M.M. (2013) On a new species of Nuchalosyllis (Polychaeta: Syllidae), a rare syllid genus only known from Brazilian waters. Journal of the Marine Biological Association of the United Kingdom, 93, 963–966.
Grube, A.E. (1850) Die Familien der Anneliden. Archiv für Naturgeschichte, 16, 249–364.
Langerhans, P. (1879) Die Wurmfauna von Madeira. Zeitschrift für wissenschaftliche Zoologie, 32, 513–592.
Lim, G.S., Balke, M. & Meier, R. (2012) Determining species boundaries in a world full of rarity: singletons, species delimitation methods. Systematic Biology, 61, 165–169.
Paresque, K., Fukuda, M.V., Nogueira, J.M.M. & San Martín, G. (2015) Amblyosyllis, Eusyllis, Odontosyllis, Perkinsyllis and Streptodonta (Annelida: Syllidae) from Brazil, with descriptions of two new species and new records for the country. Zootaxa, 4000 (3), 301–334.
San Martín, G. & Aguado, M.T. (2014) Family Syllidae. In: Schmidt-Rhaesa, A. (Chief Ed.), Handbook of Zoology Online, A Natural History of the Phyla of the Animal Kingdom. Annelida: Polychaetes. Verlag Walter der Gruyter GmbH & Co., Berlin, pp. 52.
Santos, C.S.G., Lino, J.B., Veras, P.C., Amado-Filho, G.M., Francini-Filho, R.B., Motta, F.S., Moura, R.L. & Pereira-Filho, G.H. (in press). Environmental licensing on rhodolith beds: insigths from a worm. Natureza & Conservação.