Craspedacusta iseana
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| Craspedacusta iseana | ||||||||||||
| ( Oka & Hara , 1922) |
Craspedacusta iseana (Japanese common name : ise-mamizu kurage ) is a presumably extinct freshwater medusa . The species is known only from three adult male specimens that were collected on September 22, 1921 in an old well in Tsu in the former Japanese province of Ise (now Mie Prefecture ). However, the type material was later lost.
features
The diameter is 18 mm. The screen is flat rather than hemispherical. The stomach stalk ends in four simple mouth lobes that extend below the edge of the umbrella. The central stomach is large. The upper section is conical with a wide square base that narrows downwards. The sex organs that develop in adult animals from the junction of the radial canals are massive. The edge of the screen is slightly curved. 104 to 128 tentacles are arranged in six to seven rows. There are similar numbers of round or oval statocysts . However, they lack the tubular projections as in other Craspedacusta species. The nettle cells are not located in warts or papillae, but are scattered directly over the surface of the tentacles. Craspedacusta iseana is closely related to the freshwater jellyfish ( Craspedacusta sowerbii ). It differs from it in the absence of the velar canal at the edge of the umbrella, the smaller umbrella size in the adult stage, fewer tentacles and the different shape of the statocysts and stinging cells. The polyp shape is unknown.
die out
The well in Tsu was destroyed in 1922 and the species has not been rediscovered since then.
literature
- Cheryl Lewis, Masao Migita, Hiroshi Hashimoto, and Allen G. Collins: On the occurrence of freshwater jellyfish in Japan 1928–2011: eighty-three years of records of mamizu kurage (Limnomedusae, Olindiidae) In: Proceedings of the Biological Society of Washington 125 (2): p. 165-179. 2012