Limnomedusae is an order of hydrozoans.
Taxonomy
The taxon was erected by Danish marine biologist Paul Lassenius Kramp in 1938 to accommodate certain families of hydrozoans with life histories. It includes genera with medusae with ecto-endodermal statocysts and with gonads alongside their radial canals, and also genera which have polyps that are not covered by a theca. Molecular analysis performed by Collins in 2006 has since shown that the Limnomedusae are not monophylic. The family Armorhydridae, which contains a single genus and a single species, Armorhydra janowiczi, is found living in coarse sediment, has hollow tentacles and has no radial canals. It seems to share few morphological features with the other families and probably belongs elsewhere. The inclusion of Microhydrulidae is also dubious. The medusa stage is not known and the tiny polyp has no tentacles nor mouth.
Systematic list
The World Register of Marine Species currently lists the following families and genera:
- Family Armorhydridae <small>Swedmark & Teissier, 1958</small>
- Genus Armorhydra<small> Swedmark & Teissier, 1958</small>
- Family Microhydrulidae <small>Bouillon & Deroux, 1967</small>
- Genus Microhydrula<small> Valkanov, 1965</small>
- Genus Rhaptapagis<small> Bouillon & Deroux, 1967</small>
- Family Monobrachiidae <small>Mereschkowsky, 1877</small>
- Genus Monobrachium<small> Mereschkowsky, 1877</small>
- Family Olindiidae <small>Haeckel, 1879</small>
- Genus Aglauropsis<small> Mueller, 1865</small>
- Genus Astrohydra<small> Hashimoto, 1981</small>
- Genus Calpasoma<small> Fuhrmann, 1939</small>
- Genus Craspedacusta<small> Lankester, 1880</small>
- Genus Cubaia<small> Mayer, 1894</small>
- Genus Eperetmus<small> Bigelow, 1915</small>
- Genus Gonionemus<small> A. Agassiz, 1862</small>
- Genus Gossea<small> L. Agassiz, 1862</small>
- Genus Hexaphilia<small> Gershwin & Zeidler, 2003</small>
- Genus Limnocnida<small> Günther, 1893</small>
- Genus Maeotias<small> Ostroumoff, 1896</small>
- Genus Nauarchus<small> Bigelow, 1912</small>
- Genus Olindias<small> Mueller, 1861</small>
- Genus Scolionema <small>Kishinouye, 1910</small>
- Genus Vallentinia<small> Browne, 1902</small>
References