Monday 28 April 2014

Two new species of Zoanthid Coral from Australia and Japan.

Zoanthids are unusual Corals with similarities to both the reef-forming calcareous skeleton excreting Scleractinian Corals and the larger, free living Sea Anemones. Most species are colonial, with individual polyps connected by tissue as in the Scleractinians, but few species produce any form of mineralized tissue themselves, instead incorporating sand particles or other hard material into their body walls. Zoanthids are found throughout the Oceans, from shallow coastal waters to the deep oceans, but most species are found on shallow tropical reefs, many of these reef species incorporating symbiotic Dinoflagellate Algae into their bodies (zooxanthellae).

In a paper published in the journal ZooKeys on 29 November 2012, James Reimer of the Molecular Invertebrate Systematics and Ecology Laboratory at the University of the Ryukyus and the Marine Biodiversity Research Program of the Japan Agency for Marine-Earth Science and Technology and Yuka Irei and Takuma Fujii of the Graduate School of Engineering and Science at the University of the Ryukyus describe two new species of Zoanthid Coral from the Middle Ryukyu Islands of southern Japan and around Heron Island, on the Great Barrier Reef in Australia. Both species are placed in the genus Neozoanthus, which previously contained only a single species from Madagascar. 

Zoanthid Corals of the genus Neozoanthus are considered unusual in that they are partially encrusting Corals which form an encrusting sand skeleton around their bases leaving their oral ends free, and in having a combination of internal features found in two separate Zoanthid suborders, the Macrocnemina and Brachycnemina. They are considered to be part of the Suborder Brachycnemina, but are placed in their own family, the Neozoanthidae, separate from the two other families in the group, the encrusting Sphenopidae and non-encrusting Zoanthidae.

The first new species is named Neozoanthus caleyi, in honour of Julian Caley of the Australian Census of Coral Reef Ecosystems. The species has polyps reaching 2-3 mm in height and 2-5 mm in width when fully open. The mouth of each polyp is surrounded by 28-40 tentacles. The species is highly variable in colour, ranging from white, to grey-blue, to a deep red. Some specimens had white, yellow or light blue dots on their bodies and black, white or fluorescent blue bands on the tentacles. Neozoanthus caleyi typically forms colonies of less than 100 polyps. The species was found living on the Sykes Reef and in the Heron Channel, both parts of the Great Barrier Reef close to Heron Island, at depths of between 4 m and 29 m.

Colony of Neozoanthus caleyi growing on Sykes Reef close to Heron Island on the Great Barrier Reef, Queensland, at a depth of 9 m. James Reimer in Reimer et al. (2012).

The second new species described is named Neozoanthus uchina; Uchina is the word used to describe Okinawa Island in the local, Okinawan dialect. The species has polyps reaching 2-8.5 mm in height and 2.2-5.1 mm in diameter when fully open. The mouth of each polyp is surrounded by 32-42 tentacles. Again the polyps varied in colour from white to grey-blue to deep red, with light blue or yellow dots on the body and black, white or fluorescent blue bands on the tentacles. The species formed colonies of less than 100 polyps, and was found in the waters around Okinawa and neighbouring islands from the intertidal zone to depths of 25 m. Extensive surveys of the North and South Ryukyus, the Japanese Mainland, Taiwan and the Ogasawara Islands have found no trace of this coral, suggesting it is endemic to the Middle Ryukyus.

Colony of Neozanthus uchina at at Tebiro Beach on Kagoshima Island in the Middle Ryukyus. Masami Obuchi in Reimer et al. (2012).

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