Sunday 2 June 2024

Glossobalanus weii: A new species of Enteropneust Hemichordate from Hainan Island, China.

The Superphylum Deuterostomia is one of the major divisions of the Animal Kingdom, comprising three Phyla, the well-known Echinoderms (Sea Urchins, Starfish, etc.) and Chordates (the group which includes the Vertebrates), and the less familiar Hemichordates. The Hemichordates, while not a major part of modern marine faunas, were an ecologically significant group in the Palaeozoic, and understanding them has been an important part of understanding the history of the Deuterostomes as a group. Taxonomically, the Hemichordates are divided into two groups, the Enteropneusts, or Acorn Worms, and the Graptolithoidea, a group which includes the living benthic Pterobranches and Palaeozoic planktonic Graptolites (although it has been claimed that at least one Pterobranch is actually a living, benthic, Graptolite).

Acorn Worms have bodies divided into three portions, an-acorn shaped proboscis, a thick fleshy collar, and a long worm-like bodies. Most Acorm Worms are between 9 and 45 cm in length, though the largest reach about 1.5 m. Acorn Worms typically live in burrows, using their proboscis to scrape food from the surrounding sediments, though some deep-sea species area active on the sea floor, and will even venture into the water column for brief periods. Seven species of Acorn Worm have been recorded from the waters around China, two of which, Glossobalanus polybranchioporus and Saccoglossus hwangtauensis are accorded first class protected status by the Chinese government, with the remaining five species granted second class protected status.

In a paper published in the journal ZooKeys on 27 May 2024, Xianan Fu, Weijian Guo, Zhongwen Ding, and Wenliang Zhou of the Center for Evolution and Conservation Biology at the Southern Marine Science and Engineering Guangdong Laboratory, and Funwen Wei, also of the Center for Evolution and Conservation Biology at the Southern Marine Science and Engineering Guangdong Laboratory, and of the Key Laboratory of Animal Ecology and Conservation Biology at the Institute of Zoology of the Chinese Academy of Sciences, and the College of Forestry at Jiangxi Agricultural University, describe a new species of Acorn Worm from Hainan Island, China.

The new species was discovered during a field study of the coast around the village of Toudong on the northern coast of Hainan Island in February and July 2023. It is placed in the genus Glossobalanus, and given the specific name weii, in honour of Fuwen Wei to commend his contributions to Zoology and Conservation biology.

External form of Glossobalanus weii. (A) Whole body of female GML-23021883041 under natural conditions. (B) Proboscis and collar of paratype male GML-23021883042. (C) Branchial region dorsal side photo of paratype male GML-23021883042. (D) Intestinal canal containing food. (E) Hepatic region photo of paratype male GML-23021883042. Fu et al. (2024).

The examined specimens of Glossobalanus weii are between 176 and 196 mm in length, with a proboscis twice as long as the collar, a dark spot on its tip. The collar is covered in longitudinal pleats, with the posterior part being broad, its dorsal margin is shorter than its ventral margin. Specimens of Glossobalanus weii are delicate and broke up easily when placed on a flat surface, making it necessary to examine and photograph them in water.

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