High species diversity of the soft coral family Xeniidae (Octocorallia, Alcyonacea) in the temperate region of Japan revealed by morphological and molecular analyses

Abstract

The soft coral family Xeniidae, commonly found in tropical and subtropical regions, consists of 20 genera and 162 species. To date, few studies on this family have been conducted in Japan, especially at higher latitudes. Although molecular phylogenetic analyses have recently been used to distinguish soft coral species, it is difficult to identify species and genera in this family due to the limited taxonomic indices and high morphological variation. In this study, we found a large Xeniidae community off the coast of Oshima Island (31°31.35'N, 131°24.27'E) at Miyazaki, Kyushu Island, located in the temperate region of Japan. The species composition and molecular phylogenetic relationships were investigated to uncover the species diversity of Xeniidae in this community. A total of 182 xeniid specimens were collected and identified to the species level, after which the samples were molecularly analyzed using a mitochondrial marker (ND2) and a nuclear marker (ITS) to infer the phylogenetic relationships. A total of 14 xeniid species were identified, including five undescribed species from five genera (Anthelia, Heteroxenia, Sympodium, Xenia, and Yamazatum). Miyazaki was identified as having the highest xeniid species diversity in Japan. The molecular phylogenetic trees inferred from each marker recovered very similar topologies: four genera (Anthelia, Heteroxenia, Sympodium, and Yamazatum) were monophyletic, whereas one (Xenia) was polyphyletic. Thus, except for Xenia, the morphological characteristics used for traditional taxonomy well reflected the phylogeny of the Xeniidae at the genus level. On the other hand, our results show that further taxonomic revisions of Xenia are needed.

Beyond coral-algal regimes: high taxonomic resolution surveys and trait-based analyses reveal multiple benthic regimes

“…Identification of coral reef benthic organisms to species or even genus level is extremely challenging, especially from visual census or imagery (Althaus et al 2015), which probably has restrained researchers from applying trait-based approaches to whole coral reef benthic communities. Not only many groups of benthic organisms are highly understudied (Wee et al 2017), but many other organisms such as sponges or soft corals require advanced genetic tools or microscopic examination for their taxonomic classification (McFadden et al 2017;Ruiz et al 2017;Koido et al 2019). Here, we show that even if visual identification of many coral reef benthic organisms to species level remains impossible, the classification of organisms at the highest taxonomic level possible, which for some organisms may just be at the morphological level (i.e.…”

High taxonomic resolution surveys and trait-based analyses reveal multiple benthic regimes in North Sulawesi (Indonesia)

“…Identification of coral reef benthic organisms to species or even genus level is extremely challenging, especially from visual census or imagery 48 , which probably has restrained researchers from applying trait-based approaches to whole coral reef benthic communities. Many benthic organisms are highly understudied 49 , whilst others such as sponges or soft corals require advanced genetic tools or microscopic examination for their taxonomic classification 50 – 52 . Here, we show that even if visual identification of many coral reef benthic organisms to species level remains impossible, the classification of organisms at lower levels, which for some organisms may just be at the morphological level (i.e., sponges) 53 , still yields high quality data on which trait-based approaches can be applied.…”

Terpenoids from Marine Soft Coral of the Genus Xenia in 1977 to 2019

“…The assessment of cytotoxicity against cancer cell lines is the most frequent biological evaluation reported for these terpenes, and most of them were not widely tested for their biological potential. An investigation of the diversity in soft coral family Xeniidae revealed that Xenia was polyphyletic [ 68 ]. This suggested that it might not be suitable to place soft coral belonging to the genus Xenia in a single taxon as their morphological characteristics used for traditional taxonomy are not well reflected in the phylogeny in this genus [ 68 ].…”

“…An investigation of the diversity in soft coral family Xeniidae revealed that Xenia was polyphyletic [ 68 ]. This suggested that it might not be suitable to place soft coral belonging to the genus Xenia in a single taxon as their morphological characteristics used for traditional taxonomy are not well reflected in the phylogeny in this genus [ 68 ]. A recent study from Maloney and McFadden’s group suggested that chemical studies in the last 50 years on soft coral Sarcophyton may have unknowingly comprised different cryptic species of Sarcophyton glaucum , leading to apparently distinctive chemical variation [ 69 ].…”