Rhysia
| Rhysia | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the family | ||||||||||||
| Rhysiidae | ||||||||||||
| Brinckmann , 1965 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Rhysia | ||||||||||||
| Brinckmann , 1965 |
Rhysia is a marine genus of the Hydrozoa (Hydrozoa). It is the only genus in the Rhysiidae family . Three types are currently known.
features
The hydroid polyps are sessile or stolonal and polymorphic; that is, weir, feeding and sex polyps are differentiated. The hydrorhiza is tubular and covered with perisarc . The feeding polyp is columnar and bare. It has either a wreath of filiform tentacles or a few thick tentacles around the mouth cone with a stinging cell cushion. Defense polyps, if present, are encased in perisarc up to the tip. The gonads are similar to sexual polyps, they are only on one side of the body. The male sexual polyp with three or four filiform tentacles, the female with or without tentacles. It transforms into a structure similar to a spore sac. Gonophores or Medusa buds are not formed. The endoderm forms a piston (spadix) in which an egg is formed which, after fertilization, develops into a planula larva. The planula larva is released through a tear in the spadix.
Geographical occurrence
The three species have so far been detected from the Gulf of Naples (Mediterranean Sea) from 50 m depth, the west coast of Canada ( British Columbia ) (0.5 to 20 m depth) and McMurdo Bay (Antarctica) (depth not specified). Evidence of the family from Japanese waters is questionable.
Systematics
According to the "World Hydrozoa Database", the family only includes one genus with three species. The type species of the genus Rhysia is Rhysia autumnalis :
-
Rhysia Brinckmann, 1965
- Rhysia autumnalis Brinckmann, 1965
- Rhysia fletcheri Brinckmann-Voss, Lickey & Mills, 1993
- Rhysia halecii (Hickson & Gravely, 1907)
swell
literature
- Jean Bouillon, Cinzia Gravili, Francesc Pagès, Josep-Maria Gili, Fernando Boero: An introduction to Hydrozoa. In: Mémoires du Muséum national d 'Histoire naturelle, 194 , Publications Scientifiques du Muséum, Paris 2006, ISBN 978-2-85653-580-6
- Marymegan Daly, Mercer R. Brugler, Paulyn Cartwright, Allen G. Collin, Michael N. Dawson, Daphne G. Fautin, Scott C. France, Catherine S. McFadden, Dennis M. Opresko, Estefania Rodriguez, Sandra L. Romano & Joel L. Stake: The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa, 1668: 127-182, Wellington 2007, ISSN 1175-5326 Abstract - PDF
- Anita Brinckmann-Voss, DM Lickey and CE Mills: Rhysia fletcheri (Cnidaria, Hydrozoa, Rhysiidae), a new species of colonial hydroid from Vancouver Island (British Columbia, Canada) and the San Juan Archipelago (Washington, USA). Canadian Journal of Zoology, 71 (2): 401-406, Ottawa 1993 ISSN 0008-4301 text and illustrations