Research Article |
Corresponding author: Asako K. Matsumoto ( amatsu@gorgonian.jp ) Academic editor: Bert W. Hoeksema
© 2015 Asako K. Matsumoto, Leen P. van Ofwegen.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Matsumoto AK, van Ofwegen LP (2015) Melithaeidae of Japan (Octocorallia, Alcyonacea) re-examined with descriptions of 11 new species. ZooKeys 522: 1-127. https://doi.org/10.3897/zookeys.522.10294
|
Japanese melithaeid type material is re-examined and re-described. The sclerites of the different species are depicted using Scanning Electron Microscopy. All Japanese species of the family Melithaeidae treated here belong to the genus Melithaea and are endemic to Japanese waters. Old museum material and newly collected specimens from Japanese waters are identified after comparison with this type material. Acabaria modesta var. abyssicola is regarded a separate species, here named Melithaea abyssicola (Kükenthal, 1909). In addition, 11 new species are described: M. boninensis sp. n., M. doederleini sp. n., M. isonoi sp. n., M. keramaensis sp. n., M. oyeni sp. n., M. ryukyukensis sp. n., M. sagamiensis sp. n., M. satsumaensis sp. n., M. suensoni sp. n., M. tanseii sp. n., and M. tokaraensis sp. n.. Pleurocorallium confusum Moroff, 1902, Pleurocoralloides formosum Moroff, 1902, Melitodes flabellifera Kükenthal, 1908, and Melitodes densa Kükenthal, 1908 are synonymized with Melithaea japonica (Verrill, 1865). We have designated a neotype for Melithaea mutsu Minobe, 1929. A key to the Japanese melithaeids is presented.
Melithaea , taxonomy, neotype, synonymy, deep water
Gorgoniam corals of the family Melithaeidae (Anthozoa: Octocorallia) are wide-spread and common on rocky sea bottoms of the Indo-Pacific Ocean (
Although the family is easily separated from other octocoral families, melithaeid species are quite difficult to distinguish from each other because of similarity of sclerite forms. In Japan and adjacent waters a total of 15 species and three varieties of melithaeid coral were described previously.
Unfortunately, all these species were poorly described and figured making identification of melithaeids in Japanese waters next to impossible. Therefore an attempt was made to re-describe these species and at the same time identify newly collected material for better understanding of species variation.
Per specimen a small piece of the distal part of a branch was dissolved in a 4% household bleach solution to isolate sclerites. The sclerites were washed with demineralised water, dried on a hot plate, mounted on SEM stubs, and coated with Pd/Au for SEM imaging. For this, either a JEOL JSM6490LV scanning electron microscope was operated at high vacuum at 10 kV, or a a JEOL JSM6510LA scanning electron microscope with a Quick Carbon Coater SC-701C, SANYU ELECTRON was used.
Material transferred to the
We follow
Descriptions of old Japanese material collected by Japanese used “hiro” (Japanese fathom) as the depth unit. One Japanese fathom (hiro) is usually 1.43 m, occasionally 1.51 m, whereas, it is 1.818 m for the length unit on land. The old depth unit fathom is also converted to 1.8288 m. When it was not clear whether the collector used fathom or hiro, the converted depth has wider ranges.
AKM
Asako K. Matsumoto collection, Planetary Exploration Research Center (
BIK The Biological Institute on Kuroshio, Kochi, Japan
BMNH
British
ME (UPSZTY) Museum of Evolution, Uppsala, Sweden
NBC (
UMZC
1 | Colony with abundant anastomoses |
M. boninensis sp. n. / M. habereri
|
– | Anastomoses may be present but never many | 2 |
2 | Mostly spindles in coenenchyme, few capstans and derivatives may be present | 3 |
– | Capstans and derivatives abundant | 4 |
3 | Calyces without clubs | M. modesta |
– | Calyces with leaf clubs | M. nodosa |
4 | Calyces without clubs | M. mutsu |
– | Calyces with clubs | 5 |
5 | Capstans and derivatives in small numbers | 6 |
– | Capstans and derivatives predominant | 8 |
6 | Spindles wide and long, up to 0.30 mm long | 7 |
– | Spindles mostly short, up to 0.10 mm long, with prominent tubercles | M. corymbosa |
7 | Capstans slightly unilaterally spinose | M. undulata |
– | Capstans strongly unilaterally spinose | M. isonoi sp. n. |
8 | Double disks and clubs resembling flower buds absent | 9 |
– | Double disks or clubs resembling flower buds present | 14 |
9 | Clubs and unilaterally spinose spheroids with very spiny head | M. frondosa |
– | Calyces with thorn clubs or leaf clubs | 10 |
10 | Calyces with thorn clubs |
M. arborea / M. japonica
|
– | Calyces with leaf clubs | 11 |
11 | Disk spindles present | 12 |
– | No disk spindles | 13 |
12 | Coenenchymal spindles slender, up to 0.04 mm wide | M. tenuis |
– | Coenenchymal spindles thick, up to 0.06 mm wide, almost twice as wide as in M. tenuis | M. tanseii sp. n. |
13 | Coenenchymal spindles slender, up to 0.04 mm wide | M. sagamiensis sp. n. |
– | Coenenchymal spindles thick, up to 0.07 mm wide | M. suensoni sp. n. |
14 | Calyx clubs up to 0.25 mm long, polyp sclerites weakly tuberculate | M. tokaraensis sp. n. |
– | Calyx clubs only up to 0.15 mm long, polyp sclerites with tubercles or leaves | 15 |
15 | Coenenchymal clubs resemble flower buds | M. doederleini sp. n. |
– | Coenenchymal clubs differently shaped | 16 |
16 | Unilaterally foliate spheroids present | M. satsumaensis sp. n. |
– | No unilaterally foliate spheroids present | 17 |
17 | Double disks very wide, up to 0.10 mm | M. oyeni sp. n. |
– | Double disks mostly 0.05 mm wide | 18 |
18 | Spindles up to 0.20 mm long, disk spindles up to 0.10 mm long | 19 |
– | Spindles and disk spindles up to 0.15 mm long | M. keramaensis sp. n. |
19 | Spindles can be very wide, more than 0.05 mm wide | M. ryukyuensis sp. n. |
– | Spindles at the most 0.05 mm wide | M. abyssicola |
Acabaria modesta var. abyssicola:
?Acabaria modesta abyssicola:
Holotype
Colony branched in one plane with few anastomoses (Fig.
Colony white, sclerites colorless.
Melithaea abyssicola occurs in Sagami Bay, off the Izu Islands, and Tosa (Kochi Prefecture)(Fig.
The species resembles Melithaea sagamiensis sp. n., but differs in having much smaller double disks, up to 0.05 mm long.
We have tentatively included BMNH 1921.10.26.24-2 (Fig.
Melitodes arborea:
Holotype
Colony bushy (Fig.
Red with paler polyps, sclerites orange, tentacle sclerites colorless.
The name of collector A. Austin could actually be Alan Owston (
The colony depicted by
According to
Holotype
The holotype is 8 cm long and 4.5 cm wide, branching is in two parallel planes, and with a holdfast (Fig.
The colony and sclerites are orange.
The species is only known from the Ogasawara Islands (= Bonin Islands) (Fig.
Etymology. The species is named after the type locality, the Bonin Islands.
This is the first record of Melithaea from this island group. The colony shape of paratype
Acabaria corymbosa:
Syntype
Colony bushy with anastomoses; end branches flattened (Fig.
Colony red with yellow tentacles; tentacle and pharynx sclerites colorless, all others pink.
Pacific coast of Japan; Sagami Bay; Izu Isls.; Boso Peninsula (Chiba Prefecture); Otsuchi (Sanriku, Iwate Prefecture); Otsuki (Tosa, Kochi Prefecture); and East China Sea; off Nagasaki; off Kerama Is.(Fig.
The other syntype is in Hamburg,
We included a number of specimens in M. corymbosa, which show differences from the description above. Because of the limited material and rather small differences we refrain from describing them as new species. The specimens differ as follows:
Holotype
Colony broken up, consisting of four fragments (Fig.
Colony fragments red, polyp sclerites light yellow, all others orange.
Sagami Bay (Fig.
The species is named after the collector, Ludwig H.P. Döderlein.
The coenenchymal clubs of this species look like flower buds, similar to those described for Melitaea retifera Lamarck, 1916 by
Psilacabaria frondosa:
Acabaria frondosa:
Syntypes UPSZTY 2164 (old number
Colonies branched in parallel planes, no anastomoses (Fig.
White with colorless sclerites.
Only known from Hirado Strait, Nagasaki, East China Sea (Fig.
The clubs and spinose spheroids with very spiny heads are characteristic for the species.
Acabaria habereri:
Acabaria aff. habereri:
Acabaria harbereri [sic]:
? Acabaria habereri:
None, according to
- after
Yellowish orange.
According to
?Acabaria sp. A:
Holotype
The holotype is 12 cm long and 11 cm wide, branching is in one plane and a holdfast is lacking (Fig.
Points with slightly bent spindles up to 0.20 mm long, distal end with leaves (Fig.
The colony is orange as are most sclerites; a few are yellow colored.
The species is named after the late Prof. Naohide Isono who has worked on Japanese zoological history from the Edo to Meiji period, in appreciation of informing the first author about the collectors data in this publication.
The species resembles M. japonica but differs in having leaf clubs in the calyces. It resembles M. tenuis regarding the unilaterally spinose spheroids, but it has longer spindles in the coenenchyme. It could be Acabaria sp. A. of
Mopsella japonica:
Melitella japonica:
? Acabaria japonica:
Acabaria japonica (in part):
Acabaria japonica:
Pleurocorallium confusum:
Pleurocoralloides confusum:
Pleurocoralloides formosum:
Melitodes flabellifera:
M. flabellifera var. reticulata:
M. flabellifera var. cylindrata:
Melitodes densa
?Melithaea flabellifera:
?Melithaea densa:
Holotype of Mopsella japonica BMNH 1946.1.14.207 dried sclerites of the type
Colony bushy with few anastomoses. Branches flattened in the plane of branching and polyps arranged bilaterally. Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig.
Red with yellow polyps. Variation: red (most colonies), pink, with yellow or white polyps, tentacle and pharynx sclerites colorless, all others orange; or colonies yellow with all sclerites yellow; or white with yellow polyps with polyp sclerites yellow and all others colorless.
M. japonica is found at the eastern Pacific side of Japan; Sagami Bay, Izu Peninsula, Boso Peninsula, Nagasaki (Kyushu Is.), Shimo-Chikura (Kagoshima Prefecture, Kyushu Is.), Cape Makurazaki (Kagoshima Prefecture, Kyushu Is.), Otsuchi Bay (Sanriku, Iwate Prefecture); and at the western Sea of Japan side; Oga peninsula(Akita Prefecture) (Fig.
The examined type material of Mopsella japonica was fragmented. In Harvard we only found one microscope slide (
Despite the small remainder of the type we could link it with other species described from Sagami Bay. Apparently this is the most common shallow-water species of the region,
M. densa is also reported to occur in shallow water. According to
M. flabellifera has been described with two variations: M. flabellifera var. reticulata from Sagami Bay, 80–250 m depth. It differs in having many anastomoses, and no flattened branches, color orange red, sclerites bigger and more spinose. Depository of material is unknown.
M. flabellifera var. cylindrata from an unknown locality in Japan also lacks flattened branches, color red with yellow polyps, sclerites are less spinose. Two syntypes are reported to be in Frankfurt,
In northern Japan we found quite a number of specimens:
We found three specimens with extreme slender sclerites: BIK-G224 (Fig.
Holotype
The holotype is a 12 cm long fragment without holdfast (Fig.
Colony red with white calyces and polyps. Coenenchymal sclerites orange, calyx and polyp sclerites colorless.
The paratype is very much alike the holotype regarding color and sclerites.
The species is only known from the Kerama Islands (Fig.
Etymology. The species is named after its type locality, the Kerama islands.
The species mostly resembles M. abyssicola but differs in having longer disk spindles but shorter normal spindles. It also has more finely sculptured polyp sclerites.
Acabaria modesta
Not Melithaea modesta (Nutting, 1911) = Melithaea planoregularis (Kükenthal, 1910).
Syntype
Colony branched in one plane with few anastomoses (Fig.
Colony white, sclerites colorless.
Pacific side of Japan (Fig.
The species is easily recognized by its white colony color, rather smooth polyp sclerites, and presence of spindles only.
Melithaea mutsu
Neotype
Colony broken up, consisting of three fragments, bushy with few anastomoses. The largest fragment is 7.3 cm long without holdfast (Fig.
Colony red, sclerites orange.
The tentacle platelets were missing. The description and images provided by Minobe are inadequate to identify melithaeids and we were unable to find the depository of the material. As Minobe’s material was collected near Sai, as is our material, we concluded that we have the same species and designated a neotype here. The species is similar to M. corymbosa, but lacks clubs in the calyces and disk spindles in the coenenchyme.
Melitodes nodosa:
Acabaria nodosa:
Not Melitodes nodosa: Thomson 1911: 876 (South Africa).
Syntype, BMNH 1947.3.22.6, New Hebrides, Challenger st. 177, 60-120 fms (86-219 m), dried sclerites, coll. Prof. S.J. Hickson; syntype, BMNH 89.5.27.117, Hyalonema-Ground (Nishi-no yodomi), South of Japan, 35°11'N, 139°28'E, Challenger st. 232, 345 fms (631 m), 12 May 1875, figured specimen (= Acabaria nodosa Prof. Hickson), old label book 2, p. 12; syntype, BMNH 89.5.27.118 Hyalonema-ground (Nishi-no yodomi), south of Japan, 35°11'N, 139°28'E, Challenger st. 232, 345 fms (631 m), bottom green mud, 12 May 1875, figured specimen (= Acabaria nodosa Prof. Hickson), old label book 2, p. 12.
BMNH 89.5.27.117 (Fig.
Reddish brown, polyps yellow, axis yellowish-red; reddish nodes. Sclerites yellow, those of the polyps a bit paler, the smallest tentacle and the pharynx sclerites colorless.
BMNH 89.5.27.118 (Figs
New Hebrides, Sagami Bay (Fig.
Holotype
The holotype is a 8 cm long fragment with holdfast (Fig.
Colony orange with yellow polyps, coenenchymal sclerites orange, polyp ones yellow.
Off the Izu Islands (Fig.
The species is named after Mr. T.J.G.M. van Oyen (NBC) in appreciation of the many microscope slides he prepared for the second author.
The species mostly resembles Melithaea abyssicola but has overall somewhat larger sclerites, a difference difficult to notice when not having both species at hand. However, the double disks of M. oyeni sp. n. are strikingly different, much wider than those of M. abyssicola (compare Fig.
Melithaea sp. A:
Holotype
The holotype is a 14.5 cm long fragment without holdfast (Fig.
Colony orange with yellow polyps. Part of calyx sclerites and all polyp sclerites yellow, all others orange.
The material of
Holotype
The holotype (
White, all sclerites colorless.
The paratypes are also fragmented.
Pacific side of Japan; Sagami Bay, off Sendai (Miyagi Prefecture), Otsuchi Bay (Sanriku, Iwate Prefecture); and Sea of Japan side, off Okushiri Is. (Fig.
The species is named after the type locality, Sagami Bay.
We included BMNH 62.7.16.62(61?) in Melithaea sagamiensis sp. n. despite its slightly different sclerites (Figs
Holotype
The holotype is a 16.5 cm long colony with holdfast (Fig.
Colony orange with yellow polyps, coenenchymal sclerites orange, polyp ones yellow.
Off Cape Sata misaki, Kagoshima Prefecture (Fig.
The species is named after the type locality, Satsuma, the old name of Kagoshima Prefecture.
This species is unique by its unilaterally foliate spheroids and spindles with complex tubercles.
Holotype
Colony branched in one plane, with slender branches (Fig.
White with orange calyces and polyps. Sclerites of calyces and polyps faint pink, all others colorless.
The species is named after the collector, E. Suenson, who belonged to the Telegraph company Great Nordic Ltd. (Store Nordiske), established in 1869 at Denmark (
This species resembles M. sagamiensis sp. n., but differs by its thicker coenenchymal spindles.
Holotype
The holotype (
Colony white with the larger yellowish nodes shining through the coenenchyme. All sclerites colorless.
Izu Isls (Fig.
Etymology. The species is named after the R/V Tansei-maru.
The paratype (
Acabaria tenuis:
Acabaria aff. tenuis:
Not Acabaria tenuis: Nutting 1911: 45 (Indonesia).
? Acabaria tenuis:
Syntype
Colony branched in one plane, with slender branches (Fig.
Colony red with white/yellow polyps, polyp sclerites colorless or yellow, all others orange.
Colonies can be yellow with all sclerites yellow or white with all sclerites colorless.
Sagami Bay, and now South to East China Sea (Fig.
We did not examine
Holotype
Colony branched in one plane, broken up while collecting (Fig.
Colony red, all sclerites orange.
Only known from off the Tokara Islands. (Fig.
Etymology. The species is named after the type locality, the Tokara Islands.
The species resembles M. abyssicola sp. n., M. oyeni sp. n., and M. satsumaensis sp. n., but differs in having rather smooth polyp sclerites and long calyx clubs.
Acabaria undulata
? Acabaria undulata;
Holotype
Colony branched in two parallel planes. Points with slightly bent spindles up to 0.25 mm long, distal end with more developed tubercles (Fig.
Colony red, tentacle sclerites colorless, all others pink.
AKM 502 is yellow with yellow sclerites.
Southern Pacific coast of Japan, north to Sagami Bay, south to East China Sea; Suruga Bay, off Taito-Saki Cape, Boso Peninsula; off Tanega-shima Is., Koshiki Knoll., Danzyo Basin, off Kagoshima (Fig.
The type specimen clearly has damaged sclerites, probably caused by formalin. Recently collected material shows less rounded sclerites (Figs
The species resembles M. tenuis but differs in having longer spindles (up to 0.30 mm long versus up to 0.18 mm long in M. tenuis), and lacking unilaterally spinose spheroids. It also resembles M. corymbosa, but that species has mostly more slender, shorter spindles. Moreover, M. undulata has poorly developed tentacle sclerites compared with the other two species.
Apparently the type material is mostly lost, only a small fragment remained (Fig.
BMNH1921.10.26.24-1, Misaki, Sagami Bay, 500–600 fms, coll. A.V. Insole, No. 45;
We compared Japanese melithaeids with those described from other parts of the Indo-Pacific (
The only Japanese melithaeid species described by
Most of the already described melithaeid species could be identified again from newly collected material. However, specimens of Melithaea arborea Kükenthal, 1908 (Figs
We have tentatively included BMNH 1921.10.26.24-2 in Melithaea abyssicola. It had sclerite damage caused by formalin (Figs
We included a number of problematic specimens in M. corymbosa that showed differences. Because of the limited material and rather small differences we refrain from describing these specimens as new species:
We included BMNH 62.7.16.62(61?) in Melithaea sagamiensis sp. n. despite its slightly different sclerites (Figs
M. japonica, M. corymbosa and M. sagamiensis sp. n. were collected together. These species could not be separated on colony form but only based on their sclerites. M. japonica mostly occurs in shallow water and is the only melithaeid species of which the spawning season and growth rate is known because of their accessibility for long-term study (formerly M. flabellifera in
Sagami Bay and adjacent waters produced four new species: M. doederleini sp. n. (60–100 fms (108–183 m); Figs
Northern Japan shows the melithaeids to have a more shallow distribution: M. sagamiensis sp. n. shows a shallower distribution here than in Sagami Bay, 25–30 feet (7.62–9.14 m) (Fig.
Other new species were collected from the Ogasawara Isls. (= Bonin Islands) (M. boninensis sp. n.; Fig.
Only two melithaeids are known from the Sea of Japan (M. japonica, M. sagamiensis sp. n.), much less than the melithaeid species number of the Pacific side of Japan (14 species: M. abyssicola, M. arborea, M. boninensis sp. n., M. corymbosa, M. doederleini sp. n., M. japonica, M. modesta, M. nodosa, M. oyeni sp. n., M. sagamiensis sp. n., M. satsumaensis sp. n., M. tanseii sp. n., M. tenuis, and M. undulata) or of the East China Sea (11 species: M. frondosa, M. isonoi sp. n., M. japonica, M. keramaensis sp. n., M. modesta, M. ryukyuensis sp. n., M. satsumaensis sp. n., M. suensoni sp. n., M. tenuis, M. tokaraensis sp. n., and M. undulata). M. satsumaensis sp. n. was only found once but was counted twice, in the Pacific species and the East China Sea species because it was collected from off Sata-misaki cape at Kagoshima prefecture (Fig.
Depth limitation in the Sea of Japan and the low species richness here, can probably be explained by the geographic history of Sea of Japan. The Sea of Japan is a marginal sea. It originated 15 million years ago during the last glacial maximum (LGM). It was almost totally closed off by a sea-level drop of ca.130 m. Approximately 12.000 years BP, the warm Tsushima Current, a branch of the warm Kuroshio current, started to flow into the Sea of Japan from the South (
We synonymized four species and described 11 new species from Japanese waters. In total Japan now has 23 Melithaeidae species (including M. habereri), and two varieties.
The following persons are thanked for hospitality during visits: Dr. Bernhard Ruthensteiner, Section Evertebrata varia,