Monday, April 30, 2018

[Cnidaria • 2018] Tempuractis rinkai • First Detailed Record of Symbiosis Between a Sea Anemone (Anthozoa: Actiniaria: Edwardsiidae) and Homoscleromorph Sponge


Tempuractis rinkai  Izumi, Ise & Yanagi, 2018

in Izumi, Ise, Yanagi, Shibata & Ueshima, 2018.  
 DOI:  10.2108/zs170042 

Abstract
A new species in a new genus of sea anemone, Tempuractis rinkai gen. et sp. nov., was discovered at several localities along the temperate rocky shores of Japan. The new species is approximately 4 mm in length and has been assigned to family Edwardsiidae, because it has eight macrocnemes, lacks sphincter and basal muscles, and possesses rounded aboral end. The sea anemone, however, also has a peculiar body shape unlike that of any other known taxa. This new species resembles some genera, especially Drillactis and Nematostella, in smooth column surface without nemathybomes or tenaculi, but is distinguishable from them by several morphological features: the presence of holotrichs and absence of nematosomes. Furthermore, this edwardsiid species exhibits a peculiar symbiotic ecology with sponges. Therefore, a new genus, Tempuractis, is proposed for this species. In the field, T. rinkai sp. nov. was always found living inside homosclerophorid sponge of the genus Oscarella, which suggests a possible obligate symbiosis between Porifera and Actiniaria. The benefit of this symbiosis is discussed on the basis of observations of live specimens, both in the aquarium and field. This is the first report of symbiosis between a sea anemone and a homoscleromorph sponge.

KEYWORDSJapan; edwardsiid; intertidal; marine invertebrates; overhang; species description; symbiotic relationship; taxonomy; transmission electron microscopy (TEM)



External view of Tempuractis rinkai gen. et sp. nov. and its host sponge Oscarella sp. collected from Misaki, Kanagawa,
including a holotype (NSMT-Co 1573) and four paratypes (CMNH-ZG 08969 to 08972).

RESULTS 
Order ACTINIARIA Hertwig, 1882 
Family Edwardsiidae Andres, 1881 

Tempuractis gen. nov. 
Izumi, Ise and Yanagi
(Japanese name: tempura-isoginchaku-zoku)


Etymology. Tempura is a deep-fried, batter-coated nugget of seafood and/or vegetables in Japanese cuisine. This word comprises the first half of the Japanese name of the type species of this genus, as the shape of the actiniarian when embedded in a sponge tissue resembles shrimp tempura. The siffix -actis is commonly used in actiniarian genus names, meaning radiation of sunshine in Greek. The new genus name is feminine in gender.


Tempuractis rinkai sp. nov. 
Izumi, Ise and Yanagi, 2018
(New Japanese name: tempura-isoginchaku)

Etymology. The species epithet is dedicated to marine biological stations around Japan. The first specimens of this species were collected from a rocky shore in front of the Misaki Marine Biological Station (the University of Tokyo). This station is called “Misaki rinkai jikkenjo” in Japanese (“rinkai” means seaside and “jikkennjo” means research facility). Other specimens were collected during a subsequent faunistic survey in collaboration with other marine biological stations: Sugashima Marine Biological Laboratory (Nagoya University) and Sado Marine Biological Station (Niigata University).




図1.今回の記載に用いられたテンプライソギンチャクTempuractis rinkai gen. et sp. nov.(三崎新井浜海岸産)。 a:ノリカイメン科の1種Oscarella sp.(中央のベージュ色のかたまり。全体で1個体)の中に群生している本種。生時は、触手のみをカイメンから出している。 b:テンプライソギンチャク1個体が、カイメンの鞘状構造の中に棲息している。刺激を与えないように観察すると、図の矢印が示す通り徐々に触手を出す


Takato Izumi, Yuji Ise, Kensuke Yanagi, Daisuke Shibata and Rei Ueshima. 2018. First Detailed Record of Symbiosis Between a Sea Anemone and Homoscleromorph Sponge, With a Description of Tempuractis rinkai gen. et sp. nov. (Cnidaria: Anthozoa: Actiniaria: Edwardsiidae). Zoological Science. 35(2); 188-198. DOI:  10.2108/zs170042

カイメンと共生する新属新種のイソギンチャク - 東京大学 大学院理学系研究科・理学部 s.u-tokyo.ac.jp/ja/info/5826/

   

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