Corresponding author: Kuidong Xu (
Academic editor: B.W. Hoeksema
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
Xu Y, Zhan Z, Xu K (2020) Morphology and phylogenetic analysis of five deep-sea golden gorgonians (Cnidaria, Octocorallia, Chrysogorgiidae) in the Western Pacific Ocean, with the description of a new species. ZooKeys 989: 1–37.
Chrysogorgiids are found in all major oceans from Iceland to Antarctica, and they are conspicuous members of deep-water benthic assemblages (
The genus
The genus
During an investigation of the seamount benthic diversity in the Western Pacific Ocean and the South China Sea, we obtained 18 specimens of golden gorgonians. Based on morphological and phylogenetic analyses, they were described as one new species
One specimen of
The morphological terminology follows
The type and voucher specimens have been deposited in the Marine Biological Museum of Chinese Academy of Sciences (
Total genomic DNA was extracted from the polyps of each specimen using the TIANamp Marine Animal DNA Kit (Tiangen Bio. Co., Beijing, China) following the manufacturer’s instructions. PCR amplification for the mitochondrial genomic region 5’-end of the DNA mismatch repair protein –
The
For the phylogenetic analyses, only one known sequence was randomly selected from the conspecific sequences without genetic divergence (see Table
Worldwide in a depth range of 10–4492 m (
Kocebu Guyot in the Magellan Seamount chain, 1821 m depth.
External morphology, polyps and sclerites of
External morphology, polyps and sclerites of
For morphological measurements, see Table
Kocebu Guyot, 1821 m (
The four specimens match the holotype of
External morphology, polyps and sclerites of
External morphology, polyps and sclerites of
The four specimens of
Specimen of holotype ca. 31 cm long and 14 cm wide excluding the holdfast (Figure
External morphology and polyps of
Rods and spindles slender and coarse with many warts on surface, some of them branched, rarely with one end a little flat, longitudinally arranged in the back of tentacles and usually forming eight distinct columns, and transversally or longitudinally arranged in the base of tentacles, measuring 107–814 × 10–78 μm (length × width, the same below, Figures
Sclerites of
A seamount (tentatively named as M8) located on the Caroline Ridge with a depth range of 1506–1832 m.
Named after the type locality, the Caroline Ridge, where the species was discovered.
Found only from a seamount located on the Caroline Ridge. Colony attached to a rocky substrate (Figure
Morphological comparisons between
Characters/species |
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Specimen | holotype | MBM286353 | MBM286442 | MBM286443 | MBM286444 | holotype | holotype | paratype |
Group type | A | A | A | |||||
Branching sequence | 1/3L | 1/3L | 1/3, 1/4L, irregular | |||||
Axis | monopodial, or a little zigzagging | sympodial | monopodial | |||||
Colony shape | tree-shaped | tree-shaped | bottlebrush-like | tree-shaped | a little tree-shaped | bottlebrush-shaped | bottlebrush-shaped | tree-shaped |
Colony height (cm) | 57 | 85.5 | 55 | 50 | 110 | 31 | 16 | 50 |
Basal stem width (mm) | 2 | 7 | 1.2 | 3 | 3 | 1 | No data | 2.2 |
Interbranch distance (mm) | 16–22 | 18 | 5–22 | 11–15 | 12–24 | 6–12 | 4.3–6.8 | 7.5–15.0 |
Orthostiche interval (mm) | 50–55 | 50–55 | 37–47 | 36–47 | 44–61 | 19–35 | No data | No data |
First branch internode (mm) | 15–20 | 14–22 | 11–20 | 9–23 | 20–30 | 7–15 | 6.1–11.0 | 16 |
Polyps on internodes | 1–5 | 2–3 | 1–3 | 1–4 | 1–4 | 0 | 1–2 | No data |
Polyps on terminal branchlets | 1–6 | 1–4 | 1–4 | 1–8 | 1–8 | 1 | 1–3 | 1–6 |
Polyps height (mm) | 3 | 3–5 | 1.5–2.0 | 2–3 | 3–4 | 3–8, average 5 | 0.8–2.2 | 0.8–2.2 |
Sclerites in coenenchyme (μm) | flat elongate scales often with lobed edges | 82–200 × 10–96 | 139–420 × 16–112 | 92–266 × 15–57 | 53–379 × 10–34 | elongate scales occasionally with lobed edges | small rugged scales with less lobed edges | |
Sclerites in body wall (μm) | scales, rods and spindles | 68–190 × 7–58 at basal body; 171–516 × 20–55 in neck | 100–306 × 20–72 at basal body; 121–353 × 12–56 in neck | 80–229 × 13–82 at basal body; 207–614 × 14–76 in neck | 39–236 × 8–128 at basal body; 137–590 × 12–98 in neck | scales, rods and spindles | scales and rods | |
Sclerites in tentacles (μm) | scales and rods | 74–135 × 4–32 | 105–365 × 6–45 | 75–429 × 10–43 | 93–275 × 24–93 | rods and spindles | rods | |
Distribution | Kocebu Guyot | an unnamed seamount adjacent to the Mariana Trench | unnamed seamounts on the Caroline Ridge | an unnamed seamount on the Caroline Ridge | North Atlantic | |||
References |
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Present study | Present study |
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Atlantic Ocean, Pacific Ocean and Indian Ocean, in a depth range of 567–2311 m (
Ascension Island in the South Atlantic Ocean, 778 m depth (
MBM286485, station FX-Dive 222 (
For morphological measurements, see Table
The morphological measuring data of the specimens of
Characters/ Specimens | MBM286485 | MBM286486 | MBM286484 | MBM286487 | MBM286488 | MBM286489 |
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Species |
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Colony height (cm) | 76 | 35 | 56 | 51 | 69 | 48 |
Basal stem width (mm) | 2.7 | 1.5 | 1.0 | 2.5 | 3.0 | 2.5 |
Branching part height (cm) | 9 | 8 | – | 12 | 11 | 7 |
Branching part width (cm) | 18 | 18 | 6 | 26 | 20 | 14 |
Branch maximal length (cm) | 10 | 12 | 4 | 16 | 13 | 12 |
Branches | 2 | 2 | 22 | 14 | 7 | 6 |
Interbranch distance (mm) | – | – | 9–25 | 6–13 | 13–18 | 5–18 |
Internode length (mm) | 4–12 | 3–11 | 3–7 | 3–8 | 3–10 | 3–11 |
First internode length (mm) | 13–24 | 12–18 | 3–8 | 5–8 | 6–8 | 6–11 |
Polyp height (mm) | 1.0–2.5 | 1.0–4.0, most 2.0 | 1.0–2.5, most 1.0 | average 1.0 | 1.0–1.5 | 1.0–1.5 |
Polyps in internode | 1, rarely 2 | 1, rarely 2 | 1, rarely 2 | 1, rarely 2 | 1, rarely 2 | 1, rarely 2 |
Polyps in terminal branchlets | 1–3 | 1–4 | 1–4 | 1–4 | 1–5 | 1–2 |
Inter-polyp distance (mm) | 1–6 | 1–4 | 2–5 | 1–3 | 0–5 | 0–4 |
Sclerites measured in tentacles (μm) | 129–433 × 17–55 | 125–467 × 21–125 | 96–450 × 10–85 | 44–542 × 6–117 | 120–492 × 12–98 | 115–460 × 14–78 |
Sclerites measured in body wall (μm) | 172–571 × 14–93 | 128–429 × 25–125 | 96–450 × 10–85 | 44–542 × 6–117 | 137–473 × 17–93 | 57–417 × 11–66 |
Sclerites measured in coenenchyme (μm) | 96–378 × 18–66 | 148–379 × 31–113 | 112–456 × 10–62 | 175–394 × 17–75 | 78–328 × 11–51 | 70–372 × 14–50 |
Figures | 7, 8 | 9, 10 | 11, 12 | 13, 14 | 15, 16 | 17, 18 |
Central Indo-Pacific Ocean (
The comparisons of the species (adults) in the genus
Characters/ Species |
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Branching part | sympodial | monopodial | unknown | sympodial* | monopodial |
Branchlets forming a sympodium | yes | yes | unknown | No* | No |
Interbranch distance (mm) | 5–18 | – | unknown | 10–18* | 9.9–17.2 |
Polyp height (mm) | 1–1.5 | 1.5–2.0 | 1.5 | 1.5–2.0 | 1.0–3.3 |
Sclerites in tentacles | rods | rods | plates | spindles | rods |
Sclerites in body wall | rods | rods and scales | rods | rods and spindles | rods and scales |
Sclerites with its shapes in coenenchyme | rods and scales elongated with slightly serrated edges and coarse surface | scales elongated with relatively smooth edges and surface | rods small, flattened, often with serrated edges and smooth surface | scales small, elongated, often with irregular shape and serrated edges. | scales and plates with many ornamentation |
Dendritic holdfast | no | no | unknown | no | yes |
Reference |
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*, putative species or questionable regarded by
MBM286484, station FX-Dive 210 (
External morphology and polyps of
Sclerites of
In juvenile (specimen MBM286484), colony slightly bottlebrush-shaped, with branches occurring on the lateral side of the stem randomly. Main stem monopodial and gracile. Branches subdivided dichotomously in multiple planes. Polyps cylindrical, occasionally present on the top of the stem. The branch coenenchyme well differentiated with a layer of sclerites. In the adults (specimen MBM286487–286489), colony like a tree shape with branches forming a similar spiral on the top of the stem. Main stem monopodial and strong. Branches subdivided dichotomously with branchlets forming a sympodium pattern in each plane. Polyps cylindrical, some of them with a slightly expanded base, absent from the stem. Branch coenenchyme usually not well differentiated.
Sclerites with same forms and arrangement in juveniles and adults, both relatively coarse with many small warts on surface, cross-shaped occasionally. Rods relatively regular, longitudinally arranged in tentacles and the upper part of the polyp body, and partially crosswise or transversely arranged on the body bottom. Scales and rods elongated, usually coarse with serrated edges, transversely arranged in coenenchyme. For detailed morphological measurements, see Table
West Sumatra (
According to
The juvenile of
External morphology and polyps of
Sclerites of
External morphology and polyps of juvenile
Sclerites of juvenile
External morphology and polyps of
Sclerites of
Southwest Pacific (Coral Sea and northeast of New Zealand), 800–1462 m depth (
External morphology and polyps of
Sclerites of
External morphology and polyps of
Sclerites of
Bellona Plateau, New Caledonia, 800–923 m depth (
MBM286490, the Ganquan Plateau in the South China Sea, 586–910 m.
No whole colony was obtained, thus the description was based on a picture (Figure
External morphology and polyps of
Rods with many small warts on surface, usually with two round ends and relatively less ornamentation, longitudinally arranged along the back of tentacles, and measuring 142–598 × 11–84 µm (Figures
Sclerites of
Bellona Plateau, Coral Sea and Otara Seamount, at southern tip of the Kermadec Ridge (
The conspecific sequences for each newly sampled species were identical, and only the holotype sequence was deposited in GenBank and analysed here. The accession number and the length are as follows:
The uncorrected pairwise distances at
Species/populations | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | |
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1 | – | |||||||||||||||||
2 | 0 | – | ||||||||||||||||
3 |
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0.16% | 0.16% | – | ||||||||||||||
4 |
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0.97% | 0.97% | 1.13% | – | |||||||||||||
5 |
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0.81% | 0.81% | 0.65% | 0.33% | – | ||||||||||||
6 | 0.81% | 0.81% | 0.65% | 0.48% | 0 | 0 | ||||||||||||
7 |
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0.81% | 0.81% | 0.65% | 0.48% | 0 | 0 | – | ||||||||||
8 | 0.97% | 0.97% | 0.81% | 0.65% | 0.16% | 0.16% | 0.16% | 0 | ||||||||||
9 | 1.13% | 1.13% | 0.97% | 0.81% | 0.33% | 0.32% | 0.32% | 0.48% | 0 | |||||||||
10 |
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1.45% | 1.45% | 1.29% | 1.13% | 0.65% | 0.65% | 0.65% | 0.81% | 0.97% | – | |||||||
11 |
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1.45% | 1.45% | 1.29% | 1.13% | 0.65% | 0.65% | 0.65% | 0.81% | 0.97% | 0.32% | |||||||
12 | 2.42% | 2.42% | 2.26% | 2.10% | 1.63% | 1.62% | 1.62% | 1.78% | 1.94% | 2.26% | 2.26% | – | ||||||
13 |
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2.42% | 2.42% | 2.26% | 2.10% | 1.63% | 1.62% | 1.62% | 1.78% | 1.94% | 2.26% | 2.26% | 0.48% | – | ||||
14 |
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2.26% | 2.26% | 2.10% | 1.94% | 1.46% | 1.45% | 1.45% | 1.62% | 1.78% | 2.10% | 2.10% | 0.32% | 0.16% | – | |||
15 | 5.33% | 5.33% | 5.17% | 4.85% | 4.55% | 4.52% | 4.52% | 4.68% | 4.52% | 5.17% | 5.17% | 5.17% | 5.17% | 5.01% | 0 | |||
16 | 5.49% | 5.49% | 5.33% | 5.01% | 4.72% | 4.68% | 4.68% | 4.85% | 4.68% | 5.33% | 5.33% | 5.33% | 5.33% | 5.17% | 0.16% | 0 | ||
17 | 4.04% | 4.04% | 3.88% | 3.55%. | 3.25% | 3.23% | 3.23% | 3.39% | 3.55% | 3.88% | 3.88% | 4.52% | 4.52% | 4.36% | 1.94% | 2.10% | 0 |
Maximum likelihood (
The
Both the morphology and molecular phylogenetic analysis support the assignment of the new species to the genus
Colonial branching pattern was regarded as one of the diagnostic characters to distinguish chrysogorgiid octocorals (
To include the juvenile morphology, we slightly extend the diagnosis of the genus
Furthermore, based on the present morphological descriptions, we provide a preliminary key to full grow grown specimens of the genus
1 | Only scales present in coenenchyme |
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– | Rods present in coenenchyme |
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2 | Rods and spindles present in polyp body wall |
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– | Rods and scales present in polyp body wall |
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3 | Plates present in tentacles and only rods in coenenchyme |
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– | Plates absent in tentacles, rods and scales present in coenenchyme |
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This work was supported by the Science & Technology Basic Resources Investigation Program of China (2017FY100804), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB42000000, XDA19060401), the National Natural Science Foundation of China (41930533, 41876178) and the Senior User Project of RV KEXUE. We thank the assistance of the crew of R/V