Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands Author Calder, Dale R. Author Faucci, Anuschka 0000-0001-9002-8987 anuschka@hawaii.edu text Zootaxa 2021 2021-12-24 5085 1 1 73 journal article 10.11646/zootaxa.5085.1.1 1175-5326 5802920 12FC3342-F2A0-4EE1-9853-9C5855076A10 Clytia linearis ( Thornely, 1900 ) Fig. 5d, e Obelia linearis Thornely, 1900: 453 , pl. 44 fig. 6. Type locality. Papua New Guinea : New Britain , Blanche Bay ( Thornely 1900 , as Obelia linearis ) . Voucher material. Laysan Island, on coralline algae, 18.ix.2002 , three colonies or colony fragments, to 7 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5416.—Laysan Island, on Halimeda sp. , 17.ix.2002 , one colony, 1.7 cm high, with gonothecae, coll. A. Faucci, ROMIZ B5417.—Gardner Pinnacles, 14.ix.2002 , two colonies or colony fragments, to 6 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5418.—Laysan Island, on Halimeda sp. , 17.ix.2002 , one colony, 3 mm high, with gonothecae, coll. A. Faucci, ROMIZ B5423. Remarks. These records of Clytia linearis ( Thornely, 1900 ) constitute the first reports of the species from the Hawaiian Islands. This well-known hydrozoan has been reported elsewhere from tropical and warm-temperate waters across the Indian and Pacific oceans [ Millard 1975 , as Clytia gravieri ( Billard, 1904 ) ; Mergner 1977 , as Campanularia ( Clytia ) gravieri ; Mergner & Wedler 1977 , as C. gravieri ; Rees & Vervoort 1987 ; Gibbons & Ryland 1989 ; Hirohito 1995 ; Watson 2000 ; Schuchert 2003 ; Xu et al . 2014b ; Mendoza-Becerril et al . 2020 ]. It is widespread in the Atlantic Ocean as well (e.g., Calder 1991a , 2013 ; Altuna Prados 1994 ; Migotto 1996 ; Lindner & Migotto 2002 ; Gravili et al . 2015 ; Oliveira et al . 2016 ). Clytia linearis occurs in a clade linked to another that includes C. hemisphaerica ( Linnaeus, 1767 ) , taken to be conspecific with C. johnstoni ( Alder, 1856 ) , the type species of Clytia Lamouroux, 1812 (e.g., Govindarajan et al . 2006 ; Leclère et al . 2009 ; Lindner et al . 2011 ; Zhou et al . 2013 ; He et al . 2015 ; Maronna et al . 2016 ; Cunha et al . 2017 , 2020 ). These molecular studies also confirm the wide geographic distribution of the species, with specimen vouchers from Brazil (São Sebastião), Italy (Torre Inserraglio) and the USA (Beaufort, North Carolina ) being very close genetically.Analyses of specimens from the Indo-Pacific region are needed to confirm the putative worldwide distribution of the species. The original date of publication of the work by Thornely, in which this binomen appeared (as Obelia linearis ), has commonly been cited as both 1899 and 1900. Rees & Vervoort (1987: 199) indicated that its publication date was “ v-1900 ”. That coincides with the date “May, 1900” on the Title Page of Willey, A., Zoological results based on material from New Britain, New Guinea , Loyalty Islands and elsewhere. Part IV that included the paper by Thornely. Her work has therefore been cited herein as “ Thornely (1900) ”. Another error in the literature warranting attention has been the frequent misspelling of Thornely’s name as “Thorneley”. A synonymy list of C. linearis has been given elsewhere ( Calder 1991a ). Reported Distribution. Hawaiian archipelago. First record. Elsewhere. Circumglobal, tropical to warm-temperate waters ( Lindner & Migotto 2002 ).