Taxonomic revision of the genus Sertularella (Cnidaria: Hydrozoa) from southern South America and the subantarctic, with descriptions of five new species

The hydroids belonging to the genus Sertularella Gray, 1848 from southern South America and the subantarctic are revised, based on both literature data and the reexamination of type specimens and additional material dealt with in earlier accounts. Thirty-two species are recognized as valid, of which five are new to science, namely S.juanfernandezensis, S. oblonga, S. recta, S. robustissima, and S. Subantarctica. Modern redescriptions of S. implexa (Allman, 1888) and S. Novarae Marktanner-Tumeretscher, 1890 are provided. Additionally, it is demonstrated that S. argentinica El Beshbeeshy, 2011 and S.jorgensis El Beshbeeshy, 2011 are junior synonyms of S. clausa (Allman, 1888) and S. valdiviae Stechow, 1923, respectively. Sertularella paessleri Hartlaub, 1901 is assigned to the synonymy of S. allmani Hartlaub, 1901, S. lagena Allman, 1876 to that of S. contorta Kirchenpauer, 1884, S. picta (Meyen, 1834), S. protecta Hartlaub, 1901 and S. margaritacea Allman, 1885 to that of S. gaudichaudi (Lamouroux, 1824), Sertularella uruguayensis Mafl6 Garzon & Milstein, 1973 to that of S. mediterranea Hartlaub, 1901, and S. Striata Stechow, 1923 to that of S. patagonica (d'Orbigny, 1842). Lectotypes are designated for S. allmani, S. antarctica Hartlaub, 1901, and S. implexa. A checklist of all species records from the study area, together with new identifications, is provided as an appendix.