(Karling (1963) mentions Opisthocystis as a subgenus of Polycystis, followed by Artois (2001). However, Sekera (1911) never described it as a subgenus, so the mentioning by Karling (1963) and Artois (2001) as a subgenus is erroneous.)
Tyler, S., Artois, T.; Schilling, S.; Hooge, M.; Bush, L.F. (eds) (2006-2025). World List of turbellarian worms: Acoelomorpha, Catenulida, Rhabditophora. Opisthocystis goettei (Bresslau, 1906) Sekera, 1911. Accessed through: Costello, M.J.; Bouchet, P.; Boxshall, G.; Arvanitidis, C.; Appeltans, W. (2025) European Register of Marine Species at: https://www.vliz.be/vmdcdata/narms/narms.php?p=taxdetails&id=143191 on 2025-05-12
Costello, M.J.; Bouchet, P.; Boxshall, G.; Arvanitidis, C.; Appeltans, W. (2025). European Register of Marine Species. Opisthocystis goettei (Bresslau, 1906) Sekera, 1911. Accessed at: https://www.marbef.org/data/aphia.php?p=taxdetails&id=143191 on 2025-05-12
original description(ofPolycystis roosevelti Graff, 1911)Graff, L. V. (1911). Alocoela, Rhabdocoela und Alloeocoela des Ostens de Vereinigden Staaten. Mit Nachtüngen zu dem marinen Turbellarien Orotavas und der Küste Europas. Zeitschrift für wissenschaftliche Zoologie. 99: 68-65; 1-108., available online athttps://biodiversitylibrary.org/page/9755776 page(s): 66, t. 4, f. 24, 28 [details]
basis of recordFaubel, A.; Noreña, C. (2001). Turbellaria, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 123-136 (look up in RoR) [details] Available for editors
additional sourceEvdonin, L. A. (1970). The proboscis apparatus in the family Polycystidae (Turbellaria, Neorhabdocoela, Kalyptorhynchia). In: "Studies in the evolutionary morphology of invertebrates". Ed. A.V. Ivanov. State University Leningrad. 5–53.[details] Available for editors
additional sourceKarling, T. G. (1963). Die Turbellarien ostfennoskandiens. V. Neorhabdocoela. 3. Kalyptorhynchia. Fauna Fenica. 17: 5-59.[details] Available for editors
additional sourceSchockaert, E. R.; Jouk, P. E. H.; Martens, P. M. (1989). Free-living Plathelminthes from the Belgian coast and adjacent areas. In: Wouters, K.; Baert, L. (Ed.) (1989). Proceedings of the Symposium Invertebrates of Belgium. pp. 19-25. (look up in RoR) [details]
new combination referenceSekera, E. (1911). Studien über Turbellarien. Sitzungsberichte der königligen Böhmischen Gesellschaft der Wissenschaften zu Prag. 13: 1–38: 1 plate.[details]
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