Accepted by B. Bentlage: 18 Jun. 2014; published: 13 Aug. 2014 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2014 Magnolia Press Zootaxa 3852 (1): 001–050 www.mapress.com/zootaxa/ Article 1 http://dx.doi.org/10.11646/zootaxa.3852.1.1 http://zoobank.org/urn:lsid:zoobank.org:pub:7DE3BCBA-E5F0-4F0D-B2FD-B5B59E4DAE51 New species and new records of hydroids (Cnidaria: Hydrozoa) from Chile HORIA R. GALEA 1, 6 , DIRK SCHORIES 2, 3 , GÜNTER FÖRSTERRA 4, 5 & VERENA HÄUSSERMANN 4, 5 1 Hydrozoan Research Laboratory, 405 Chemin des Gatiers, 83170 Tourves, France. E-mail: horia.galea@gmail.com 2 Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile 3 Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus-von-Liebig-Weg 6, 18059 Rostock, Germany. Email: dirk.schories@uni-rostock.de 4 Pontificia Universidad Católica de Valparaíso, Facultad de Recursos Naturales, Escuela de Ciencies del Mar, Avenida Brazil 2950, Valparaíso, Chile 5 Huinay Scientific Field Station, Casilla 462, Puerto Montt, Chile. Email: huinayresearch@gmail.com 6 Corresponding author Abstract A large collection of shallow-water hydroids from various Chilean provinces, ranging from Taltal (25° S) in the North, to the Strait of Magellan (53° S) in the South, was studied, and a total of 30 species are discussed in the present report. Of these, eleven are new to science: Candelabrum valdiviensis, Halecium erratum, H. humeriformis, H. maximum, H. mod- estum, H. platythecum, Hydrodendron chilense, Sertularella asymmetra, S. curta, S. pauciramosa, and Symplectoscyphus semper . The nominal species Halecium flexile Allman, 1888, included for many decades in the synonymy of H. delicatu- lum Coughtrey, 1876, is resurrected based on distinctive features displayed by its newly discovered female gonothecae. A thorough discussion is provided on several morphologically related species of the genus from various localities around the world, and data on the nematocyst complement are emphasized, allowing the distinction of an as yet undescribed species, H. tristaniensis, from Tristan da Cunha, South Atlantic, and the resurrection of H. balei Fraser, 1911 from southern Aus- tralia. Halecium tehuelchum (d’Orbigny, 1842), a poorly known species considered as of doubtful validity, is redescribed based on fertile material of both sexes. A discussion on the taxonomy of several members of the genus Hydrodendron Hincks, 1874, including the first comprehensive account of their cnidome, is provided. The male and female gonothecae of Halopteris plumosa Galea & Schories, 2012 are described for the first time. A discussion on the genus Silicularia Mey- en, 1834 is provided, and three subantarctic species are provisionally recognized based on the material in hand, viz. S. bi- labiata (Coughtrey, 1875), S. rosea Meyen, 1834, and S. hemisphaerica (Allman, 1888). Four hydroids are new records for Chile: Halecium corrugatissimum Trebilcock, 1928, Parascyphus simplex (Lamouroux, 1816), Symplectoscyphus uni- lateralis (Lamouroux, 1824), and Aglaophenia divaricata Busk, 1852, the last two being accompanied by comments on their synonymy. Two additional hydroids are only tentatively identified, viz. Hebella cf. scandens (Bale, 1888) and the allusive benthic stage of Phialella falklandica (Browne, 1902). Key words: Hydrozoans, taxonomy, new species, South America, southeastern Pacific Introduction The hydrozoan fauna of Chile, rather poorly investigated in the past, has received increasing attention during the last decade, and several taxonomic studies have been already published, namely Galea (2007), Galea et al. (2007, 2009), and Galea & Schories (2012a). A considerable collection was gathered between 2010 and 2013. Part of the material originates from local explorations carried out around Taltal (Región de Antofagasta, ca. 25° S), Valdivia (Región de los Ríos, ca. 39°), and Punta Arenas (Región de Magallanes y Antártica Chilena, ca. 53°S). Additional samples from various localities have been obtained during several expeditions carried out by the Huinay Scientific Field Station in the fjords region of southern Chile. These expeditions have explored the exposed coast in the Northern Patagonian Zone (HF7), the interior northern fjords and the large channels of the far southern cone (HF9), the canals of the exposed northern Patagonian Zone (HF11), the inner fjords of the Central Patagonian Zone (HF13), and an area