Moerisiidae Poche, 1914

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 56

Family Moerisiidae Poche, 1914

Moerisiidae Poche, 1914: 66 .

Diagnosis. Capitate hydroids with solitary hydranths, or with simple stolonal colonies having a rudimentary creeping hydrorhiza; podocysts often present. Hydranths club-shaped to bulbous; tentacles moniliform to capitate, scattered over body or restricted to a band below hypostome; sometimes with polyp buds forming proximally; hypostome elongate.

Gonophores free medusae, borne on hydranth amongst or below tentacles. Medusa bell-shaped; radial canals four, simple, unbranched; marginal tentacles solitary, 4 or more and sometimes numerous, moniliform or with transverse clasps of nematocysts; tentacle bulbs with abaxial ocelli; statocysts absent. Manubrium typically cruciform to quadrate, extending outwards as perradial manubrial lobes over proximal ends of radial canals. Gonads on manubrium and manubrial lobes.

Remarks. Authors of recent systematic works (e.g. Petersen 1990; Cairns et al. 2002; Bouillon et al. 2006; Schuchert 2010) have followed Rees (1957b, 1958) in assigning Moerisiidae Poche, 1914 to Capitata Kühn, 1913 based on nematocyst complement and medusa morphology. The presence of stenoteles and desmonemes in particular indicates a closer relationship to capitate hydroids and medusae than to Limnomedusae Kramp, 1938 , where this family had been assigned earlier ( Naumov 1960; Kramp 1961). This relationship has also been confirmed by molecular data ( Collins et al. 2006). Petersen (1979, 1990) included two genera in Moerisiidae , Moerisia Boulenger, 1908 and Odessia Paspalew, 1937 , relegating Ostroumovia Hadži, 1928 to the synonymy of Moerisia . Bouillon et al. (2006) included a third genus, Halmomises von Kennel, 1891 , in Moerisiidae but regarded its type species by monotypy, H. lacustris von Kennel, 1891 (which they misspelled as H. ancestries ), as of doubtful status. Three genera ( Moerisia , Odessia , and Halmomises ) and 12 species are assigned to the family in the World Hydrozoa Database ( Schuchert 2009). Taxonomic knowledge of Moerisiidae is still rudimentary, and current concepts of genera and species need reexamination.