Ceriantharia (Cnidaria) of the World: an annotated catalogue and key to species Author Stampar, Sergio N. Universidade Estadual Paulista (UNESP), FCL / Assis, Laboratorio de Evolucao e Diversidade Aquatica; LEDA, Departamento de Ciencias Biologicas, Assis, Brazil & Universidade Estadual Paulista (UNESP), Departamento de Zoologia, Instituto de Biociencias, Botucatu, SP, Brazil https://orcid.org/0000-0002-9782-1619 sergiostampar@gmail.com Author Reimer, James D. University of The Ryukyus, Faculty of Science, Department of Biology, Chemistry, and Marine Science, MISE (Molecular Invertebrate Systematics and Ecology) Laboratory, Okinawa, Japan & University of The Ryukyus, Tropical Biosphere Research Center, Okinawa, Japan https://orcid.org/0000-0003-0453-8804 Author Maronna, Maximiliano M. Universidade de Sao Paulo (USP), Instituto de Biociencias, Sao Paulo, SP, Brazil https://orcid.org/0000-0002-2590-639X Author Lopes, Celine S. S. Universidade Estadual Paulista (UNESP), FCL / Assis, Laboratorio de Evolucao e Diversidade Aquatica; LEDA, Departamento de Ciencias Biologicas, Assis, Brazil & Universidade Estadual Paulista (UNESP), Departamento de Zoologia, Instituto de Biociencias, Botucatu, SP, Brazil Author Ceriello, Hellen Universidade Estadual Paulista (UNESP), FCL / Assis, Laboratorio de Evolucao e Diversidade Aquatica; LEDA, Departamento de Ciencias Biologicas, Assis, Brazil & Universidade Estadual Paulista (UNESP), Departamento de Zoologia, Instituto de Biociencias, Botucatu, SP, Brazil https://orcid.org/0000-0003-1199-2773 Author Santos, Thais B. Universidade Estadual Paulista (UNESP), FCL / Assis, Laboratorio de Evolucao e Diversidade Aquatica; LEDA, Departamento de Ciencias Biologicas, Assis, Brazil & University of The Ryukyus, Faculty of Science, Department of Biology, Chemistry, and Marine Science, MISE (Molecular Invertebrate Systematics and Ecology) Laboratory, Okinawa, Japan Author Acuna, Fabian H. Instituto de Investigaciones Marinas y Costeras (Iimyc) CONICET; Facultad De Ciencias Exactas y Naturales Universidad Nacional de Mar Del Plata Funes 3250. 7600 Mar Del Plata, Argentina & Estacion Cientifica Coiba (Coiba-Aip), Clayton, Panama, Republica de Panama Author Morandini, Andre C. Universidade de Sao Paulo (USP), Instituto de Biociencias, Sao Paulo, SP, Brazil & Universidade de Sao Paulo (USP), Centro de Biologia Marinha, Sao Sebastiao, SP, Brazil https://orcid.org/0000-0003-3747-8748 text ZooKeys 2020 952 1 63 http://dx.doi.org/10.3897/zookeys.952.50617 journal article http://dx.doi.org/10.3897/zookeys.952.50617 1313-2970-952-1 961036180C3A4DE9BCC19AE0A824B9D8 4DD4C3F03B1C546FA3471BEC6C4CE3E9 53 Isarachnanthus nocturnus (den Hartog, 1977) Cerianthus natans : Verrill 1901 : 47 Ceriantheopsis sp. Pax 1924 : 94, 118-120 Arachnanthus nocturnus den Hartog, 1977: 221-230; Cairns et al. 1986 : 192-193; Uchida and Soyama 2001 : 142, 150, 152 Wirtz et al. 2003 : 115-116; Isarachnanthus nocturnus : Molodtsova 2000 : 15,17; Molodtsova 2003 : 251-252; Stampar et al. 2012 : 1-9 Isarachnanthus sp. Rodriguez et al. 2011 : 51; 52, 54 Tessera gemmaria Goy, 1979: 288-289; Rodriguez et al. 2011 : 51-55; Stampar et al. 2015c : 2162 Type locality. Piscadera Bay, Curacao , Dutch Caribbean. Distribution. Caribbean Sea, South Atlantic (Argentina; Brazil), at 1-20 m depth. Remarks. This species was described by den Hartog (1977) based on specimens from Curacao . The specific epithet is related to the nocturnal behavior of this species. This is the most studied species of the genus, as the larval development has been described and the taxonomy has been reviewed with molecular data ( Stampar et al. 2012 , 2015c ). Molodtsova (2003) argued that this species is only a synonym of Isarachnanthus maderensis , however, based on molecular and micrometric data ( Stampar et al. 2012 ) it has been shown that these two species are distinct. Type material. Naturalis Biodiversity Center, Leiden (former Rijksmuseum van Natuurlijke Historie) - RMNH.COEL.11364 (Holotype).