Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590 Author Calder, Dale R. text Zootaxa 2010 2010-08-31 2590 1 1 91 https://biotaxa.org/Zootaxa/article/view/zootaxa.2590.1.1 journal article 10.11646/zootaxa.2590.1.1 1175­5334 Genus Moerisia Boulenger, 1908 Moerisia Boulenger, 1908: 358 . Type species. Moerisia lyonsi Boulenger, 1908 , by monotypy. Diagnosis. Moerisiid hydroids with moniliform, hollow tentacles. Moerisiid medusae with moniliform tentacles; gonads smooth, forming a continuous mass extending from central manubrium to manubrial lobes. Remarks. The brackish-water genus Moerisia Boulenger, 1908 as presently constituted is widespread and relatively familiar, but most nominal species assigned to it are poorly understood taxonomically. In the Indo-west Pacific region, only the species currently known as Moerisia horii ( Uchida & Uchida, 1929 ) has been thoroughly studied in all phases of its life cycle. Nevertheless, relationships of that species to M. gemmata ( Ritchie, 1915 ) and M. gangetica Kramp, 1958 , both described from the same general region of India , or to other nominal species currently assigned to the genus ( Moerisia lyonsi Boulenger, 1908 , Caspionema pallasi Derzhavin, 1912 , Moerisia inkermanica Paltschikowa-Ostroumowa, 1925 , Moerisia alberti Leloup, 1938 , and Moerisia carine Bouillon, 1978b ), have not been adequately explored. Moreover, a number of moerisiid records worldwide attributed to M. lyonsi , including accounts of mine ( Calder 1971 ; Calder & Burrell 1967 ; Sandifer et al. 1974 ), have been based on adult medusae with numerous (>20) marginal tentacles. As originally described by Boulenger (1908) , however, mature medusae of that species normally have four tentacles. Rees & Gershwin (2000) , working with Moerisia sp. from California, believed that only one or two morphologically variable species may prove to exist in Moerisiidae Poche, 1914 . Confusion and uncertainty prevails in the taxonomy of the genus at present, and a revision of Moerisia and its species is needed. As for M. gemmata , Rees & Thursfield (1965) included it in the synonymy of M. inkermanica (as Ostroumovia inkermanica ). Although restricted to environments of low salinity, species of Moerisia are well-known to be invasive ( Purcell et al. 1999 ; Rees & Gershwin 2000 ; Ma & Purcell 2005a , b). Notably, resistant podocysts are known to occur in the life cycle, and may facilitate dispersal of these hydrozoans. Fewer than 10 species are currently included in the genus Moerisia ( Bouillon et al . 2006 ; Schuchert 2009 ). One of these, M. horii , has been reported from Hawaiian waters ( Cooke 1977 ).