A Report on Coralliidae (Cnidaria: Octocorallia) Specimens Collected from the Emperor Seamounts with Descriptions of Three New Species

Abstract

Investigations were carried out on 22 deep-water octocoral specimens in the family Coralliidae sampled from the Emperor Seamounts during 2009 to 2012. The specimens were collected from 350–1100 m deep, mostly from the southernmost region of the Emperor Seamounts. Colonies were identified by visual and microscopic observation of standard morphological characters (colony size, diameters of colony base and branches, diameter and height of autozooid mound, thickness of coenenchyme and sclerite sizes, etc.) along with supporting information from molecular DNA analysis. Half of the 22 specimens were identified as Pleurocorallium cf. pusillum (Kishinouye, 1903), suggesting that the species called “Mid” that was once harvested dominantly in this area was this species. The remaining 11 specimens were identified as genus Hemicorallium Gray, 1867. These were identified as belonging to the following species: one previously described species [H. laauense (Bayer, 1956)], three similar species [H. cf. abyssale (Bayer, 1956), H. cf. regale (Bayer, 1956), H. cf. sulcatum (Kishinouye, 1903)] and three new species (H. kaiyo sp. nov., H. muzikae sp. nov. and H. tokiyasui sp. nov.).