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

Table 8. Comparison of anatomical features of Isarachnanthus species.

	I. bandanensis	I. maderensis	I. nocturnus	I. panamensis
Marginal tentacles	Up to 40	Up to 42	Up to 60	Up to 32
Arrangement of labial tentacles	(3)413.4242.4312.4312	(1)1.11.11.11.11	(1)2.12.12.12.12	(2)431.4231.4231
Length of actinopharynx	~1/4 of gastric cavity	~2/5 of gastric cavity	~2/5 of gastric cavity	~1/2 to 1/3 of gastric cavity
Hyposulcus	~2/3 size of stomodeum	= size of stomodeum	= size of stomodeum	= size of stomodeum
Oral disc diameter	~2cm	2 cm	3.5 cm	~0.5 cm
Mesentery attached to siphonoglyph	Broad, 18 mesenteries attached	Broad, 10 mesenteries attached	Broad, 12-14 mesenteries attached	Broad, 16 mesenteries attached
Directive mesenteries	= length of Actinopharynx	> length of Actinopharynx	> length of Actinopharynx	>length of Actinopharynx
P(C)2	Long, 3/4 of gastric cavity	Short, 1/3 of gastric cavity	Short, 1/3 of gastric cavity	Long, 3/4 of gastric cavity
P(C)3	Very short, <1/8 of gastric cavity	Very short, ~1/6 of gastric cavity	Very short, ~1/5 of gastric cavity	Short, ~1/5 of gastric cavity
M1	Almost to aboral pore	Almost to aboral pore	Almost to aboral pore	Reach aboral pore
M3	Almost to aboral pore	Almost to aboral pore	Almost to aboral pore	Reach aboral pore
Cnido-glandular tract of fertile mesenteries	Present (short?)	Present	Present	Present (short?)
Cnido-glandular tract of B	Present (short?)	Present (short)	Present (short)	Present (short?)
Acontioids	Only in M1- M4	Only in M1-M6	M1-M3 (sometimes in M4 and M5)	Only in M1- M5 or absent