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| Hemicorallium osmanthogemmum Koido, 2026 |
Abstract
A new precious coral species, Hemicorallium osmanthogemmum sp. nov. (Scleralcyonacea, Coralliidae), retrieved from a depth of 550 m in Kochi Prefecture, Japan, is described, and an updated identification key for the genus Hemicorallium is provided. The new species is confirmed as belonging to the genus Hemicorallium based on the presence of nonretractile but contractile autozooids with an ovate-cylindrical shape and sclerites comprising elongated rods, 6–8-radiates and double clubs, with elongated rods present exclusively in the tentacles. Moreover, the species is distinct from all its congeners in that it has orange coenenchyme and a pink axis, with autozooids distributed only on the front side of the branch, forming clusters at the branch tips. These morphological features differ from those of all previously described species of Hemicorallium, and molecular analysis of mitochondrial sequences (16S, ND1, ND2, ND3, ND6, COI, MSH, and IGR1) further corroborates the validity of this new species. This is the first report of Hemicorallium off the coast of Kochi Prefecture, Japan.
Key words: Cnidaria, deep-sea corals, precious coral, Scleralcyonacea, Western Pacific
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| Hemicorallium osmanthogemmum sp. nov. (Holotype: KBF-OA-00436). A. ‘‘Front’’ and ‘‘back’’ of colony; B. Branch, showing autozooid (AZ); C. Exposed axis with the coenenchyme removed; D, E. Surface detail of branch, showing autozooid (AZ), siphonozooid (SZ), burrows (Bu), cluster of autozooids (CL), warts on coenenchyme surface (W), and commensal polychaete (Po). Scale bars: 50 mm (A); 10 mm (B–E). |
Class Octocorallia Haeckel, 1866
Order Scleralcyonacea McFadden, van Ofwegen & Quattrini, 2022
Family Coralliidae Lamouroux, 1812
Genus Hemicorallium Gray, 1867
Hemicorallium osmanthogemmum sp. nov.
New Japanese name. Kinmokusei-mizo-sango.
Diagnosis. The colony branches in one plane, and anastomoses are present only where broken branches come into contact with other branches. Autozooids are contracted but not retracted, and they are distributed only on one side of the colony. Spacing is almost absent on the twigs, and clusters are formed at the tips. The axis has no pits beneath the autozooids and is pale pink to pink in colour. Sclerites are predominantly radiate, and double clubs are rare. Warty rods are present only in the tentacles.
Tatsuki Koido. 2026. A New Species of Hemicorallium (Anthozoa, Octocorallia, Coralliidae), along with a revised identification key to species of the genus. ZooKeys. 1277: 339-354. DOI: doi.org/10.3897/zookeys.1277.184620 [20 Apr 2026]
