Explorations of seamounts in the Western Pacific Ocean and South China Sea resulted in collecting 18 specimens of golden gorgonians. Based on the morphology and the genetic analysis of mtMutS, they are described as one new species,Chrysogorgia carolinensissp. nov., and four known species, includingChrysogorgia dendriticaXu, Zhan & Xu, 2020,Metallogorgia melanotrichos(Wright & Studer, 1889),Metallogorgia macrospinaKükenthal, 1919, andPseudochrysogorgia bellonaPante & France, 2010.Chrysogorgia carolinensisbelongs to theChrysogorgia“group A, Spiculosae” with rods or spindles distributed in the polyp-body wall and tentacles, and differs from all of its congeners exceptC. dendriticaby the 1/3L branching sequence and amoeba-shaped sclerites at the basal polyp body. The mtMutS sequence ofC. carolinensissp. nov.has six deletion mutations compared to those of its congeners, supporting the establishment of the new species. Although no genetic variability was observed between the closely related speciesC. dendriticaandC. abludoPante & Watling, 2012, the former is different from the latter by the apparently irregular sclerites in the polyp body wall. The two specimens ofMetallogorgia melanotrichosmatch well with the original description except for relatively larger polyps, while theM. macrospinaspecimens have slightly smaller polyps than the holotype. The juvenile ofMetallogorgiahas an obvious morphological difference with the adults in the colony shape and branches, but they can be unified by the same polyps and sclerites as well as mitochondrial MutS sequences. Thus, the generic diagnosis ofMetallogorgiais slightly extended to include the morphology of juveniles. The morphology ofPseudochrysogorgia bellonaPante & France, 2010, as a new record for the South China Sea, matches well with that of the original description. In the phylogenetic trees, theChrysogorgiaspecies are separated into two clades, and whileMetallogorgiaandPseudochrysogorgiaformed a sister clade.
