Rhopalonema velatum Gegenbaur 1857: 251 Bigelow 1909: 129 Alvariño 1969: 46 Segura-Puertas 1984: 42 Alvariño 1999: 7 Segura-Puertas et al. 2010: 107 Jáquez-Bermudez et al. 2013: 39 Guerrero-Ruíz et al. 2014: 394 Gamero-Mora et al. 2015: 115 Rhopalonema velatim Foerster 1923: 47 Taxonomy and diversity of Hydrozoa (Cnidaria, Medusozoa) of La Paz Bay, Gulf of California Mendoza-Becerril, María A. Estrada-González, Mariae C. Mazariegos-Villarreal, Alejandra Restrepo-Avendaño, Luisa Villar-Beltrán, Rogelio D. Agüero, José Cunha, Amanda F. Zootaxa 2020 2020-07-01 4808 1 1 37 4SL3D Gegenbaur, 1857 Gegenbaur 1857 [151,643,1746,1773] Hydrozoa Rhopalonematidae Rhopalonema Animalia Trachymedusae 4 5 Cnidaria species velatum   Figs. 2K–L, 3A–B      Rhopalonema velatum Gegenbaur 1857: 251, pl. 9, figs. 1–5. —  Bigelow 1909: 129, pl. 2, fig. 8, pl. 45, fig. 11. —  Alvariño 1969: 46. —  Segura-Puertas 1984: 42, pl. 10, fig. 4. —  Alvariño 1999: 7, 22, 33, figs. 27a, 27b. —  Segura-Puertas et al.2010: 107. —  Jáquez-Bermudez et al.2013: 39. —  Guerrero-Ruíz et al.2014: 394, fig. 1. —  Gamero-Mora et al.2015: 115.    Rhopalonema velatim.—  Foerster 1923: 47(incorrect spelling).    Typelocality.Mediterranean Sea ( Gegenbaur, 1857).  Material examined.Medusa—PB7_13, sampling site 2 (1), immature, 27ºC; PB7_1, sampling site 3 (1), immature, 26.5ºC.   Description.Umbrella broader (1.0– 1.3 mmwide) than high ( 0.7–0.8 mmlong), with a conical apical thickening, and a well-developed velum ( 0.4 mmwide). Manubrium small ( 0.1–0.2 mmlong), with an octagonal base ( 0.3–0.4 mmwide), without peduncle, and mouth with four simple lips. Eight straight radial canals; narrow ring canal. Sixteen solid marginal tentacles, eight perradial and eight interradial. Four to eight free ecto-endodermal statocysts along each marginal tentacle. Nematocysts (length x diam.). Perradial and inter-radial marginal tentacle, stenotele (13.6–15.1 x 13.3–15.0 µm), desmoneme (6.2–6.9 x 3.6–4.6 µm). More detailed description in Mayer (1910)and Russell (1953).  Taxonomic status.Accepted. AphiaID 117865.   Distribution.In warm waters of all oceans, occasionally occurring in temperate and cold waters ( Russell 1953; Kramp 1961; Ramírez & Zamponi 1980; Segura-Puertas et al. 2010). In Mexican Pacific it has been registered in Baja California( Alvariño 1969), Baja California Sur(Punta Eugenia and locality not specified) ( Bigelow 1909; Alvariño 1969; Alvariño 1999), Sonora, Sinaloa( Alvariño 1969), Nayarit( Bigelow 1909), Jaliscoto Michoacán( Segura-Puertas 1984; Segura-Puertas et al. 2010; Jáquez-Bermudez et al. 2013; Gamero-Mora et al. 2015), Guerrero(Acapulco and locality not specified) ( Segura-Puertas 1984; Guerrero-Ruíz et al. 2014; Gamero-Mora et al. 2015) and Oaxaca( Bigelow 1909; Segura-Puertas 1984).