Checklist of Benthic Cnidaria in the SW Atlantic Ocean (54 ºS- 56 ºS) Author Schejter, L. 0000-0001-5443-4048 Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP). Paseo Victoria Ocampo 1, 7600, Mar del Plata, Argentina. Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Argentina. & schejter @ inidep. edu. ar, https: // orcid. org / 0000 - 0001 - 5443 - 4048 Author Genzano, G. 0000-0002-9818-7648 genzano @ mdp. edu. ar; https: // orcid. org / 0000 - 0002 - 9818 - 7648 genzano@mdp.edu.ar Author Pérez, C. D. 0000-0002-0866-1183 Centro Acadêmico de Vitória, Universidade Federal de Pernambuco, Rua Alto do Reservatório s / n, Bela Vista, CEP: 55608 - 680, Vitória de Santo Antão-PE, Brazil. & carlos. perez @ ufpe. br, https: // orcid. org / 0000 - 0002 - 0866 - 1183 Author Acuña, F. Estación Científica Coiba (Coiba-AIP), Clayton, Panamá, República de Panamá. Author Cordeiro, R. T. S. 0000-0002-3164-5333 Departamento de Biologia, Universidade Federal Rural de Pernambuco, Rua Dom Manuel de Medeiros, s / n, Dois Irmãos, CEP: 52171 - 900, Recife / PE, Brazil. & Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA ralfts @ gmail. com; https: // orcid. org / 0000 - 0002 - 3164 - 5333 ralfts@gmail.com Author Silva, R. A. Centro Acadêmico de Vitória, Universidade Federal de Pernambuco, Rua Alto do Reservatório s / n, Bela Vista, CEP: 55608 - 680, Vitória de Santo Antão-PE, Brazil. Author Garese, A. Author Bremec, C. S. text Zootaxa 2020 2020-11-13 4878 2 201 239 journal article 7936 10.11646/zootaxa.4878.2.1 b10a81a2-3936-425a-92b6-9e52fd7be1e7 1175-5326 4424884 F930E674-DDA9-4EC9-B0E9-3891B239C6CF Obelia longissima (Pallas, 1766) Material examined : BBB 2016: St. 23; St. 35; St. 38. Distribution: Cosmopolitan. In the southwestern Atlantic it was reported from 34°S to 55°S ( Oliveira et al. 2016 ). This is the first record of an Obelia species in MPA Namuncurá I. Remarks: Synonyms at the area are Laomedea ( Obelia ) longissima ( Vervoort 1972 ) ; Obelia gracilis (Milstein 1976) . Several colonies without gonothecae were assigned to this species. Cornelius (1975) synonymized Obelia longissima with O. dichotoma but, later on, Cornelius (1995) considered both species as valid. However, considering that some geographical records in the literature of these species are still confusing, further studies are necessary in order to confirm their validity or adopt any synonymy.