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Research Article
Melithaeidae of Japan (Octocorallia, Alcyonacea) re-examined with descriptions of 11 new species
expand article infoAsako K. Matsumoto, Leen P. van Ofwegen§
‡ Higashi Nippon International University, Fukushima and Chiba Institute of Technology (Chitech), Chiba, Japan
§ Naturalis Biodiversity Center, Leiden, Netherlands
Open Access

Abstract

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.

Keywords

Melithaea, taxonomy, neotype, synonymy, deep water

Introduction

Gorgoniam corals of the family Melithaeidae (Anthozoa: Octocorallia) are wide-spread and common on rocky sea bottoms of the Indo-Pacific Ocean (Bayer 1956, Ofwegen 1987, Williams 1992, Grasshoff 1999, 2000, Ofwegen et al. 2000, Reijnen et al. 2014). The family is distributed from tropical to cold waters, from the sea level to hundreds of meters depth in Japanese waters (Matsumoto et al. 2007, this paper).

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. Verrill (1865) was the first to describe a Japanese melithaeid, Mopsella japonica Verrill, 1865) (now Melithaea japonica), from Simoda (= Shimoda, Izu Peninsula) collected by Stimpson during the USA North Pacific Exploring Expedition. Later on it was put in the genus Acabaria (see remarks species re-description). Wright and Studer (1889) were the next authors to describe a melithaeid species, Melitodes nodosa Wright & Studer, 1889 (now Melithaea nodosa) from Hyalonema-ground (Nishi-no-Yodomi), Sagami Bay, 345 fms depth (631 m). Shortly after that Brundin (1896) described Psilacabaria frondosa Brundin, 1896 (now Melithaea frondosa) from the Hirudo Strait(= Hirado Strait, Nagasaki). The genus Psilacabaria, Ridley 1884 was synonymized with Acabaria Gray, 1859 by Kükenthal (1909). Next Moroff (1902) described two new species of octocorals from Japan, Pleurocorallium confusum Moroff, 1902 (synonymised with Melithaea japonica in this paper) and Pleurocoralloides formosus Moroff, 1902 (synonymised with M. japonica in this paper); the latter in a new genus. According to Bayer and Cairns (2003) both species belong to Acabaria. Type specimens of both were collected in Sagami Bay. Kükenthal (1908, 1909) contributed most to the Japanese melithaeid fauna, describing no less than eight species: Melitodes flabellifera (Kükenthal, 1908) (synonymised with M. japonica in this paper) from shallow water, with two varieties, M. flabellifera var. reticulata and M. flabellifera var. cylindrata; M. densa Kükenthal, 1908 (synonymised with M. japonica in this paper) from shallow water; M. arborea Kükenthal, 1908 from shallow water in Sagami Bay; Acabaria tenuis Kükenthal, 1908 (now Melithaea tenuis) from Sagami Bay, 600 m depth and Okinose bank, 80-250 m depth; A. undulata Kükenthal, 1908 (now Melithaea undulata) from Sagami Bay, 700 m depth; A. habereri Kükenthal, 1908 (now Melithaea habereri) from Sagami Bay; A. modesta Kükenthal, 1908 (now Melithaea modesta) from Sagami Bay, 80-250 m depth, with one variety abyssicola, also from Sagami Bay but from 600 m depth, and finally A. corymbosa Kükenthal, 1908 (now Melithaea corymbosa) from Misaki. Nutting (1912) recorded Mopsella dichotoma (Linnaeus, 1758) (now Melithaea dichotoma), originally decribed from South Africa, from several localities around Japan. The last to describe a melithaeid species from Japan was Minobe (1929), Melitodes mutsu Minobe, 1929 (now Melithaea mutsu) from Mutsu Bay.

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.

Material and methods

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 Naturalis Biodiversity Center (RMNH) is presented in the material section with the original AKM number between brackets.

RMNH Coel. 41916 (AKM 615; Melithaea japonica), RMNH Coel. 41942 (AKM 664; M. tenuis), RMNH Coel. 41943 (AKM 980; M. tenuis), RMNH Coel. 41936 (AKM 743; M. satsumaensis sp. n.), RMNH Coel. 41925 (AKM 1148; M. keramaensis sp. n.), RMNH Coel. 41908 (AKM 1175; M. corymbosa), RMNH Coel. 41920 (AKM 1200; M. japonica) and RMNH Coel. 41923 (AKM 1252; M. japonica) have been used in the molecular study of Reijnen et al. Of these RMNH Coel. 41916, RMNH Coel. 41942, RMNH Coel. 41920 and RMNH Coel. 41923 had identical sequences, here now identified as M. japonica. RMNH Coel. 41942 was the only identified Japanese species in the molecular study, as M. tenuis.

We follow Reijnen et al. (2014) regarding generic classification, with only two valid genera in the Melithaeidae, Melithaea and Asperaxis, with the latter genus only reported from Australia.

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.

Abbreviations

AKM Asako K. Matsumoto collection, Planetary Exploration Research Center (PERC), Chiba Institute of Technology (Chitech), Japan

BIK The Biological Institute on Kuroshio, Kochi, Japan

BMNH British Museum of Natural History, London, UK

MCZ Museum of Comparative zoologyHarvard University, Cambridge, USA

ME (UPSZTY) Museum of Evolution, Uppsala, Sweden

MZS Musée Zoologique de Strasbourg, 29 boulevard de la Victoire, Strasbourg, France

NBC (RMNH) Naturalis Biodiversity Center, formerly Rijksmuseum van Natuurlijke Historie, Darwinweg 2, P.O. Box 9517, 2300 RA Leiden, The Netherlands

NHMW Naturhistorisches Museum Wien, Austria

SMBL Seto Marine Biological Laboratory, Field Science Education and Research Center, Kyoto University, Shirahama-cyo 459, Nishi-muro-gun, Wakayama Prefecture, 649-2211, Japan

SMF Forschungsinstitut und Naturmuseum Senckenberg, Frankfurt, Germany

UMZC UniversityMuseum of Zoology Cambridge, Downing Street, Cambridge, CB2 3EJ, UK

UMUTZ UniversityMuseum of University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-0033, Tokyo, Japan

ZMB Museum für Naturkunde der Humboldt-Universität, Berlin, Germany

ZMH Zoologisches Museum Hamburg, Germany

ZMUC Zoological MuseumUniversity of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark

ZSM Zoologische Staatssammlung München, Münchhausenstraße 21, 81247 Munich, Germany

Key to Melithaea species of Japan

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

Description

Melithaea abyssicola (Kükenthal, 1909)

Figures 1, 2, 3, 4, 5, 6, 7, 8

Acabaria modesta var. abyssicola: Kükenthal 1909: 68 (Sagami Bay, Japan); Kükenthal 1919: 184; 1924: 79; Aurivillius 1931: 28 (Sagami Bay, 400–500 m).

?Acabaria modesta abyssicola: Rho et al. 1980: 55 (Korea Strait).

Material examined

Holotype ZSM 20040057, Sagami Bay, 600 m, coll. Doflein 1904/05; previously unidentified museum material: BMNH 1921.10.26.5, Misaki, Sagami Bay, 333 fms (609 m), coll. A.V. Insole, May 1921; UMUTZ-CnidG-21, Gokeba, Sagami Bay, 150–20 hiro (227–29 m), coll. K. Aoki, 18 June 1902; UMUTZ-CnidG-28, Kahiwajima Is., Tosa, Kochi Prefecture, coll. K. Kinoshita, June 1909; UMUTZ-CnidG-29, same data as UMUTZ-CnidG-28; UMUTZ-CnidG-30, same data as UMUTZ-CnidG-28; UMUTZ-CnidG-33, same data as UMUTZ-CnidG-28; UMUTZ-CnidG-101, St.5, 170 fms (possibly Japanese fms) (243–257 m), coll. I. Ijima, 2 April 1895; UMUTZ-CnidG-232, same data as UMUTZ-CnidG-28; RMNH Coel. 41900 (AKM 430), Zeni-su, off Izu Islands, 33°53'N 138°43'E, R/V Tansei-maru, KT04-06, st. ZN-3, 267.3–288.3 m, coll. A.K. Matsumoto, 3 April 2004; RMNH Coel. 41901 (AKM 571), Otsuki, Tosa, Kochi Prefecture, 32°43'N, 132°48'E, local fishermen’s boat, Kiryo-maru, st. 3, coral-net, 84.75–83.1 m, coll. A.K. Matsumoto, 7 October 2004; ?BMNH 1921.10.26.24-2, Misaki, Sagami Bay, 500–600 fms (715-1097 m), coll. A.V. Insole No. 45.

Description

Colony branched in one plane with few anastomoses (Fig. 1a). Points with slightly bent spindles up to 0.17 mm long, distal end with more developed tubercles (Fig. 2a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 2b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 2c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 2d). Coenenchyme with predominantly capstans (Fig. 3a), double disks (Fig. 3b) and disk spindles (Fig. 3c), 0.05–0.10 mm long, and small clubs of similar length (Figure 2e). Spindles, 0.10–0.20 mm long, with simple tubercles, are also present (Fig. 3d); some sclerites are intermediate between clubs and spindles (Fig. 3e). The calyces with additional clubs, up to 0.14 mm long (Fig. 2f).

Figure 1.

Melithaea abyssicola, colonies; a ZSM 20040057, holotype b AKM 571 c BMNH 1921.10.26.24-2 d UMUTZ-CnidG-28.

Figure 2.

Sclerites of Melithaea abyssicola, ZSM 20040057, holotype; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs of coenenchyme f clubs of calyx.

Figure 3.

Sclerites of Melithaea abyssicola, ZSM 20040057, holotype; a capstans b double disks c disk spindles d spindles e intermediate sclerite.

Color

Colony white, sclerites colorless.

Variation

RMNH Coel. 41900, UMUTZ-CnidG-28 (Fig. 1d), UMUTZ-CnidG-30, UMUTZ-CnidG-33, RMNH Coel. 41900 and BMNH 1921.10.26.24-2 are yellow with yellow sclerites; UMUTZ-CnidG-21, UMUTZ-CnidG-101 and UMUTZ-CnidG-232 are orange colonies; UMUTZ-CnidG-29 is red. RMNH Coel. 41901 is orange with red polyps (Fig. 1b), polyp sclerites pink, all others yellow. The sclerites of RMNH Coel. 41901 are similar to the holotype (Figs 4, 5) but it has somewhat longer coenenchymal spindles, up to 0.25 mm long (Fig. 5d).

Figure 4.

Sclerites of Melithaea abyssicola, RMNH Coel. 41901; a point spindles b collaret spindle c tentacle sclerites d pharynx rods e clubs of coenenchyme f clubs of calyx.

Figure 5.

Sclerites of Melithaea abyssicola, RMNH Coel. 41901; a capstans b double disks c disk spindles d spindles.

Distribution

Melithaea abyssicola occurs in Sagami Bay, off the Izu Islands, and Tosa (Kochi Prefecture)(Fig. 8).

Remarks

Kükenthal (1909) probably made this a variety of Acabaria modesta Kükenthal, 1908 because the colonies and sclerites of these two species have the same color. However, morphologically the sclerites of these two species are completely different by M. modesta lacking clubs, double disks and disk spindles.

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. 1c) in Melithaea abyssicola as it was collected together with BMNH 1921.10.26.5 by the same collector at the same locality, only at different depths. However, the specimen has clubs and disk spindles but lacks the double disks and shows sclerite damage caused by formalin (Figs 6, 7).

Figure 6.

Sclerites of Melithaea abyssicola, BMNH 1921.10.26.24-2; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e capstans and disk spindles of coenenchyme.

Figure 7.

Sclerites of Melithaea abyssicola, BMNH 1921.10.26.24-2; a clubs of coenenchyme b clubs of calyx c spindles.

Figure 8.

Distribution of Melithaea abyssicola (*), Melithaea arborea (●), and Melithaea boninensis sp. n. (■).

Melithaea arborea Kükenthal, 1908

Figures 8, 9a, 10, 11

Melitodes arborea: Kükenthal 1908: 193; 1909: 59, figs 61–63, Pl. 4 fig. 26 (Japan); Kükenthal 1919: 150; 1924: 62; Hickson 1937: 122.

Material examined

Holotype ZMH C3305, Sagami Bay (collection number in Kükenthal (1908) incorrect as 63305), coll. A. Austin.

Re-description

Colony bushy (Fig. 9a). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 10a). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 10b). Coenenchyme with capstans (Fig. 10c), about 0.05 mm long, the bigger ones are spheroids (Fig. 10d); small clubs of similar length; spindles, 0.10–0.30 mm long, with simple or complex tubercles (Figs 10e, 11). The axis has smooth and sparsely tuberculate rods (Fig. 10f).

Figure 9.

a Melithaea arborea, ZMH C3305 holotype b Melithaea boninensis sp. n., holotype UMUTZ-CnidG-205 c paratype UMUTZ-CnidG-255. Scale bars 1 cm.

Figure 10.

Sclerites of Melithaea arborea, ZMH C3305; a tentacle sclerites b pharynx rods c capstans d spheroids e spindles f axis rods.

Figure 11.

Spindles of Melithaea arborea, ZMH C3305.

Color

Red with paler polyps, sclerites orange, tentacle sclerites colorless.

Distribution

The name of collector A. Austin could actually be Alan Owston (Isono 1988), an English trader (import and export merchant and naturalist), who used to collect material of deep-water species. Therefore we suspect M. arborea to grow in deeper water. So far it is only found in Sagami Bay (Fig. 8).

Remarks

The colony depicted by Kükenthal (1908) could actually be the basal part of a much larger colony. As with M. japonica, many sclerites are disintegrated, and therefore we could not depict the small clubs of the coenenchyme. Also, the sample available to us had hardly any polyp sclerites, since only a few tentacle rods were present (Fig. 10a). Therefore, we assume that they also had disintegrated. Kükenthal (1908) described collaret and point sclerites as being 0.20 mm long, the tentacle rods 0.15 mm long. He did not mention the presence of capstans and small clubs. We found no sclerites resembling clubs referable to calyces and only a few sclerites with a tendency to be unilaterally spinose.

According to Kükenthal (1908) the species resembles mostly M. japonica. Indeed the sclerites of these two species are very similar, M. japonica showed somewhat more developed unilaterally spinose sclerites and some sclerites resembling clubs. Bearing in mind the colony fragment of M. arborea resembles a basal part we do not exclude the possibility M. arborea and M. japonica represent one and the same species. Therefore, they were given the same position in the key to species identification.

Melithaea boninensis sp. n.

Figures 8, 9b–c, 12, 13

Material examined

Holotype UMUTZ-CnidG-205, Ogasawara Isls. (= Bonin Isls.), Japan, coll. S. Hirota and Sekiguchi, 11 April 1894; paratype UMUTZ-CnidG-255, same data as holotype.

Description

The holotype is 8 cm long and 4.5 cm wide, branching is in two parallel planes, and with a holdfast (Fig. 9b). The stem is 5 mm wide, the end branches only 1 mm wide. The colony has many anastomoses. The polyps are situated all around the branches, the calyces are dome-shaped, and the polyps are retracted. Points with slightly bent spindles up to 0.15 mm long, distal end with leaves (Fig. 12a). Collaret with bent spindles up to 0.20 mm long, middle part with more tubercles or side branches (Fig. 12b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 12c). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 12d). Coenenchyme with capstans (Fig. 12e), unilaterally foliate spheroids (Fig. 12f), 0.05–0.10 mm long and small clubs of similar length (Fig. 12g); spindles (Fig. 13b) and unilaterally foliate spindles (Fig. 13a) are 0.10–0.20 mm long. The calyces with longer clubs, up to 0.15 mm long (Fig. 12h). Most coenenchymal sclerites have complex tubercles.

Figure 12.

Sclerites of Melithaea boninensis sp. n., UMUTZ-CnidG-205; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e capstans f unilaterally foliate spheroids g clubs of coenenchyme h clubs of calyx.

Figure 13.

Sclerites of Melithaea boninensis sp. n., UMUTZ-CnidG-205; a unilaterally foliate spindles of coenenchyme b spindles of coenenchyme.

Color

The colony and sclerites are orange.

Distribution

The species is only known from the Ogasawara Islands (= Bonin Islands) (Fig. 8).

Etymology. The species is named after the type locality, the Bonin Islands.

Remarks

This is the first record of Melithaea from this island group. The colony shape of paratype UMUTZ-CnidG-255, collected at the same time with G205, looks similar toZ-CnidG-205, but it has disintegrated sclerites. The colony is slightly smaller and brighter orange-colored (Fig. 9c). Its sclerites are similar to those of the holotype. This is the only species that looks like M. habereri (Kükenthal, 1908), having many anastomoses, but its sclerites are quite different, many with leaves, while Kükenthal described spiny sclerites for M. habereri.

Melithaea corymbosa (Kükenthal, 1908)

Figures 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27

Acabaria corymbosa: Kükenthal 1908: 197; 1909: 70, figs 81-83, pl. 6 fig. 31 (Misuki (= Misaki), Japan); Kükenthal 1919: 187; 1924: 81; Aurivillius 1931: 24 (Sagami Bay); Hickson 1937: 177.

Material examined

Syntype ZMB 5814, Misaki (Japan), coll. Doflein, 1904/05; previously unidentified museum material: ZMUC ANT-000587, Okinose, Sagami Bay, Japan, 100 fms (143–183 m), coll. Dr. Th. Mortensen, 26 June 1914; ZMUC ANT-000588; Sagami Bay, Japan, 80–120 fms (114–219 m), coll. Dr. Th. Mortensen, 6–19 June 1914; ZMUC ANT-000590, Okinose, Sagami Sea, 100 fms (143–183 m), coll. Dr. Th. Mortensen, 15 June 1914; ZMUC ANT-000646, Off Nagasaki, 32°15'N, 128°12'E, 90 fms (165 m), coll. Dr. Th. Mortensen, 15 May 1914; ZMUC ANT-000654, Okinose, Sagami Sea, 100 fms (143–183 m),, coll. Dr. Th. Mortensen, 23 June 1914; ZMUC ANT-000659, Okinose, Sagami Bay, 200 fms (286–366 m), coll. Dr. Th. Mortensen, 1 July 1914; ZMUC ANT-000661, same data as ZMUC ANT-000654; ZMUC ANT-000650, Off Misaki, Sagami Bay, ca.250 fms (ca.358–457 m), coll. Dr. Th. Mortensen, 10 June 1914; UMUTZ-CnidG-15, Japan; UMUTZ-CnidG-17, Gorgonian cave at Koajiro, Misaki, Sagami Bay, 16 July 1897; UMUTZ-CnidG-23 (G-23a), same data as UMUTZ-CnidG-17; UMUTZ-CnidG-268 (G-37d), Misaki, Sagami Bay, coll. K. Kinoshita, summer 1906; UMUTZ-CnidG-41, Awa Kominato, Boso Peninsula, Chiba Prefecture, coll. sp. no. 78, April 1885; UMUTZ-CnidG-271 (G-41b), same data as UMUTZ-CnidG-41; UMUTZ-CnidG-199, Sengenzuka-Aoyamadashi line, Sagami Bay, 100 hiro (143–151 m), coll. H. Matsumoto and H. Chiba, 20 July 1913; RMNH Coel. 41902 (AKM 223), South of Mera-se bank, Sagami Bay, 34°59.6'N, 139°41.1'E - 34°59.7'N, 139°41.1'E, 81–78 m, R/V Shinyo-maru, St.1, coll. A.K. Matsumoto, 17 October 2003; AKM 225, same data as RMNH Coel.41902; AKM 242, South of Mera-se Minami knoll, 34°54.8'N, 139°39.7'E - 34°54.8'N, 139°39.9'E, 348–312 m, R/V Shinyo-maru, coll. A.K. Matsumoto, 18 October 2003; AKM 245, South of Mera-se bank, Sagami Bay, 34°54N 139°39E, 315-365m, R/V Shinyo-maru, coll. A.K. Matsumoto, 18 October 2003; AKM 246, South of Mera-se Minami knoll, 34°54.2'N, 139°39.9'E - 34°54.3'N, 139°39.3'E, 348–312 m, R/V Shinyo-maru, coll. A.K. Matsumoto, 18 October 2003; AKM 248, same data as AKM245; AKM 253, Sagami Bay, 33°26.3'N, 139°42.3'E - 33°26.5'N, 139°42.0'E, 157–172 m, R/V Shinyo-maru, K-32, St. 18, coll. A.K. Matsumoto, 21 October 2003; AKM 299, Sagami Sea, 33°27'N, 139°42'E, 200–211 m, R/V Shinyo-maru, coll. A.K. Matsumoto, 21 October 2003; RMNH Coel. 41903 (AKM 513), Otsuki, Tosa, Kochi Prefecture, 132°50.44'E 32°37.66'N, - 132°47.88'E 32°37.56'N, 114 m, local fishermen’s boat, Kiryo-maru, st.1, coral net, coll. A.K. Matsumoto, 7 October 2004; AKM 578, off Ohakozaki cape, Otsuchi, Iwate Prefecture, 39°21.338N 142°00.721E, 75 m, R/V Yayoi, St. 2.3.4, coll. A.K. Matsumoto, 22 February 2005; AKM 595, entrance of Otsuchi Bay, Otsuchi, Iwate Prefecture, 39°21.858N 141°59.972E, 65.6 m, R/V Yayoi, St.1, coll. A.K. Matsumoto, 12 September 2005; RMNH Coel. 41904 (AKM 840b), East of Jogashima Spur, 35°03.52'N, 139°37.43'E - 35°04.17'N, 139°37.52'E, 397–286 m, R/V Tansei-maru, KT07-31, st. 8, coll. A.K. Matsumoto, 25 November 2007; RMNH Coel. 41905 (AKM 886), Hachijo Is., Izu Isls., 33°20.9082'N, 139°41.1841'E33°21.0775'N, 139°40.4931'E, 213–185 m, R/V Tansei-maru, KT07-31 (Kuramochi leg.), St.14 (L-7-200), Chain Bag Dredge, coll. A.K. Matsumoto, 26 November 2007; RMNH Coel. 41906 (AKM 928), Hachijo Is., Izu Isls., 33°22.5320'N, 139°40.492'E33°22.3111'N, 139°40.2511'E, 202–145 m, R/V Tansei-maru, KT07-31, St.15 (L-7-100), Chain Bag Dredge, coll. A.K. Matsumoto, 26 November 2007; RMNH Coel. 41907 (AKM 949), Toshima Is., Izu Isls., 34°33.1102'N, 139°17.4102'E34°33.6524'N, 139°17.6725'E, 143 m, R/V Tansei-maru, KT07-31, Kuramochi leg., St.22 (L-3-100), Chain Bag Dredge, coll. A.K. Matsumoto, 27 November 2007; RMNH Coel. 41908 (AKM 1175), off Kerama Is. Okinawa Prefecture, East China Sea, 127°27.70'E – 127°27.95'E, 26°04.59'N, – 26°04.56'N, 160–153 m, R/V Tansei-maru, KT08-33 cruise, St. KR-07, Chain Bag Dredge, coll. A.K. Matsumoto, 16 December 2008; RMNH Coel. 41909 (AKM 1176), same data as AKM 1175; RMNH Coel. 41910 (AKM 1320), off Kerama Islands. Okinawa Prefecture, East China Sea, 26°00'N, 127°12'E, 100–97 m, R/V Tanisei-maru, KT08-33, st. KR-3, coll. A.K. Matsumoto, 18 December 2008; RMNH Coel. 41911 (AKM 1321), same data as AKM 1320; AKM 1519, off Funakoshi Bay, Iwate Prefecture, 101 m, R/V Yayoi, St. 2-5, CO N, coll. A.K. Matsumoto, 26 April 2010; AKM 1525, off Oshima Is. Entrance of Otsuchi Bay and Funakoshi Bay, Iwate Prefecture, 39°22.085'N, 142°01.152'E, 97 m, by R/V Yayoi, 1 m biological dredge. coll. A.K. Matsumoto, 26 April 2010; AKM 1545, off Ohako-zaki Cape, Otsuchi, Iwate Prefecture, 86.5 m, R/V Yayoi, st. 2-2, coll. A.K. Matsumoto, 27 April 2010; RMNH Coel. 41912 (AKM 1602), South East off Taito-saki, Boso Peninsula, 35°09.31'N, 140°48.57'E35°09.60'N, 140°49.40'E, 311–325 m, R/V Tansei-maru, KT95-05, st. TB14, coll. S. Ohta, 26 April 1995; RMNH Coel. 41913 (AKM 1603), Okinoyama Basin, Sagami Bay, 86–88 m, R/V Tansei-maru, KT87-19, st. OKI, 1 m ORI biological dredge, coll. S. Ohta, 10 December 1987.

Re-description

Colony bushy with anastomoses; end branches flattened (Fig. 14a). Points with slightly bent spindles up to 0.20 mm long, distal end with spines (Fig. 15a). Collaret with bent spindles up to 0.25 mm long, middle part with more tubercles (Fig. 15b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 15c). These platelets are up to 0.17 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 15d). Coenenchyme with predominantly spindles, 0.10-0.18 mm long (Fig. 16b), with simple or complex tubercles. A few capstans and unilaterally spinose spindles also present (Fig. 13f). Calyces with thorn clubs, 0.10-0.12 mm long (Fig. 16a).

Figure 14.

Melithaea corymbosa, a ZMB 5814, syntype b ZMUC ANT-000587 c RMNH Coel. 41903 d RMNH Coel. 41908 e RMNH Coel. 41911. Scale bars 1 cm.

Figure 15.

Sclerites of Melithaea corymbosa, ZMB5814 syntype; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e axis rod f unilaterally spinose spindles of coenenchyme.

Figure 16.

Sclerites of Melithaea corymbosa, ZMB5814 syntype; a clubs of calyces b spindles of coenenchyme.

Color

Colony red with yellow tentacles; tentacle and pharynx sclerites colorless, all others pink.

Variation

ZMUC ANT-000587 (Fig. 14b) has a different colony shape than the syntype but the same locality, color and sclerites (Figs 17, 18). The species shows much color variation, RMNH Coel. 41902 has colorless and pink coenenchymal sclerites and yellow polyp ones. RMNH Coel. 41907 has orange coenenchymal sclerites and pink polyp ones. ZMUC ANT-000654 has colorless and pink coenenchymal sclerites, orange collaret and point sclerites and yellow tentacle ones; RMNH Coel. 41904 and RMNH Coel. 41905 show orange coenenchymal sclerites and colorless polyp ones; ZMUC ANT-000646 has a mixture of yellow and orange sclerites in both coenenchyme and polyps; RMNH Coel. 41906 is yellow with yellow sclerites. RMNH Coel. 41912 has an unique color pattern in M. corymbosa, red colony with white axis. Its sclerites are also slightly different, the polyp sclerites are less tuberculate, clubs of calyces are smaller, longer ones being very scarce, and the unilaterally spinose spindles are less developed (Fig. 19). This is probably due to the preservation in formalin. RMNH Coel. 41913 has extremely well developed unilaterally spinose spindles (Fig. 20).

Figure 17.

Sclerites of Melithaea corymbosa, ZMUC ANT-000587; a point spindles b collaret spindles c tentacle sclerites.

Figure 18.

Sclerites of Melithaea corymbosa, ZMUC ANT-000587; a clubs of calyces b spindles of coenenchyme.

Figure 19.

Sclerites of Melithaea corymbosa, RMNH Coel. 41912; a tentacle rods b point spindles c collaret spindles d pharynx rods e unilaterally spinose spindles of coenenchyme f clubs g spindles of coenenchyme.

Figure 20.

Sclerites of Melithaea corymbosa, RMNH Coel. 41913; a point spindles b collaret spindles c tentacle sclerites d unilaterally spinose spindles of coenenchyme e spindles of coenenchyme.

Distribution

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. 27).

Remarks

The other syntype is in Hamburg, ZMH C3299.

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: RMNH Coel. 41903 has a red colony color with white polyps (Fig. 14c), all coenenchymal sclerites are colorless, the axis sclerites are pink. It differs from M. corymbosa in having more capstans and derivatives of capstans (Figs 21, 22). RMNH Coel. 41908 (Fig. 14d) and RMNH Coel. 41909 are white colonies with colorless sclerites. They differ from M. corymbosa in having many small clubs with rounded heads (Figs 23, 24). RMNH Coel. 41910 and RMNH Coel. 41911 (Fig. 14e) have more unilaterally spinose spindles than normal for M. corymbosa (Figs 25, 26). Both colonies come from the same locality but have different color patterns. RMNH Coel. 41910 is orange with white calyces and polyps; sclerites of polyps and calyces colorless, others orange; RMNH Coel. 41911 is red with orange sclerites. ZMUC ANT-000646 has an orange colony with white polyps, sclerites yellow with colorless polyp sclerites. It differs from M. corymbosa in having more capstans and derivatives of capstans. In this respect it resembles RMNH Coel. 41903, from which it differs in having overall more tuberculate sclerites.

Figure 21.

Sclerites of Melithaea corymbosa, RMNH Coel. 41903; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs.

Figure 22.

Sclerites of Melithaea corymbosa, RMNH Coel. 41903; a capstans, derivatives of capstans, and unilaterally spinose spindles of coenenchyme b spindles of coenenchyme.

Figure 23.

Sclerites of Melithaea corymbosa, RMNH Coel. 41908; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axis rods f clubs g unilaterally spinose spheroids h capstan.

Figure 24.

Sclerites of Melithaea corymbosa, RMNH Coel. 41908; a spindles of coenenchyme b unilaterally spinose spindles of coenenchyme.

Figure 25.

Sclerites of Melithaea corymbosa, RMNH Coel. 41911; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs.

Figure 26.

Sclerites of Melithaea corymbosa, RMNH Coel. 41911; a unilaterally spinose spindles of coenenchyme b spindles of coenenchyme.

Figure 27.

Distribution of Melithaea corymbosa (*), problematic specimens (●).

Melithaea doederleini sp. n.

Figures 28a, 29, 30, 35

Material examined

Holotype MZS-Cni61, Sagami Bay, 60-100 fms (143-183 m), coll. Doederlein, 1882.

Description

Colony broken up, consisting of four fragments (Fig. 28a). Points with slightly bent spindles up to 0.25 mm long, distal end with leaves (Fig. 29a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 29b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 29c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 29d). Coenenchyme with predominantly capstans (Fig. 30a), and small clubs resembling flower buds (Fig. 30b), up to 0.10 mm long. Spindles, 0.10-0.20 mm long, with simple tubercles, are also present. (Fig. 30c). The calyces with additional clubs, up to 0.15 mm long (Fig. 30d).

Figure 28.

a Melithaea doederleini sp. n., MZS-Cni61 holotype b Melithaea frondosa (Brundin, 1896), UPSZTY 2164 syntypes c Melithaea isonoi sp. n., UMUTZ-CnidG-34 holotype.

Figure 29.

Sclerites of Melithaea doederleini sp. n., MZS-Cni61; a point spindles b collaret spindles c tentacle sclerites d pharynx rods.

Figure 30.

Sclerites of Melithaea doederleini sp. n., MZS-Cni61; a capstans b clubs of coenenchyme c spindles of coenenchyme d clubs of calyces.

Color

Colony fragments red, polyp sclerites light yellow, all others orange.

Distribution

Sagami Bay (Fig. 35).

Etymology

The species is named after the collector, Ludwig H.P. Döderlein.

Remarks

The coenenchymal clubs of this species look like flower buds, similar to those described for Melitaea retifera Lamarck, 1916 by Ofwegen et al. (2000), but that species has unilaterally foliate spheroids, a type of sclerite not present in the present material.

Melithaea frondosa (Brundin, 1896)

Figures 28b, 31, 32, 35

Psilacabaria frondosa: Brundin 1896: 14, pl. 1 fig. 5, pl. 2 fig. 5 (Hirudo Strait (= Hirado Strait), Japan).

Acabaria frondosa: Kükenthal 1909: 61; Kükenthal 1919: 185; 1924: 80; Hickson 1937: 181.

Material examined

Syntypes UPSZTY 2164 (old number UUZM 67), Hirudo Strait (= Hirado Strait), Nagasaki, Japan, 33°10'N, 129°18'E, coll. Kapt. Suenson.

Re-description

Colonies branched in parallel planes, no anastomoses (Fig. 28b). End branches with bilateral polyp arrangement. Points with slightly bent spindles up to 0.30 mm long, distal end with more developed tubercles (Fig. 31a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 31b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 31c). These platelets are up to 0.20 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 31d). Coenenchyme with capstans (Fig. 32a), unilaterally spinose spheroids (Fig. 32b) 0.05–0.10 mm long; small clubs of similar length (Fig. 32c); spindles 0.10–0.20 mm long (Fig. 32d). The calyces with longer clubs, up to 0.14 mm long (Fig. 32e). Most sclerites have complex tubercles. The axis has smooth and sparsely tuberculate rods (Fig. 31f).

Figure 31.

Sclerites of Melithaea frondosa, UPSZTY 2164; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod.

Figure 32.

Sclerites of Melithaea frondosa, UPSZTY 2164; a capstans b unilaterally spinose spheroids c clubs of coenenchyme d spindles of coenenchyme e clubs of calyces.

Color

White with colorless sclerites.

Distribution

Only known from Hirado Strait, Nagasaki, East China Sea (Fig. 35).

Remarks

The clubs and spinose spheroids with very spiny heads are characteristic for the species.

Melithaea habereri (Kükenthal, 1908)

Acabaria habereri: Kükenthal 1908: 197; Kükenthal 1909: 65, figs 70–72, pl. 5 fig. 29 (Sagami Bay, Japan); Kükenthal 1919: 179; Kükenthal 1924: 76.

Acabaria aff. habereri: Aurivillius 1931: 26, fig. 4 (Sagami Bay, 700 m).

Acabaria harbereri [sic]: Hickson 1937: 177.

? Acabaria habereri: Rho et al. 1980: 52 (Korea Strait).

Material examined

None, according to Kükenthal (1908) the material was deposited in München but it was not found there.

Re-description

- after Kükenthal (1908): Colony branched in parallel planes, many anastomoses. Points and collaret sclerites 0.18 mm long, point sclerites are spiny clubs. Colony with spindles, in the calyx 0.15-0.18 mm long, in the coenenchyme about 0.18 mm long.

Color

Yellowish orange.

Remarks

According to Kükenthal (1908) this species mostly resembles M. undulata. From the description it most resembles M. corymbosa. One other Japanese melithaeid shows many anastomoses, namely M. boninensis sp. n. For differences see our discussion on that species.

Melithaea isonoi sp. n.

Figures 28c, 33, 34, 35

?Acabaria sp. A: Aguilar-Hurtado et al. 2012: 63, fig. 7 (Okinawa).

Material examined

Holotype UMUTZ-CnidG-34, Coral Reef, Cape Chinen, Okinawa Prefecture, Japan, 15 April 1901; paratype UMUTZ-CnidG-256, same data as holotype.

Description

The holotype is 12 cm long and 11 cm wide, branching is in one plane and a holdfast is lacking (Fig. 28c). The stem is 10 mm wide, the end branches only 2 mm wide. The colony has no anastomoses. The polyps are situated biserially on the branches, the calyces are dome-shaped, and the polyps retracted.

Points with slightly bent spindles up to 0.20 mm long, distal end with leaves (Fig. 33a). Collaret with bent spindles up to 0.20 mm long, middle part with more developed tubercles (Fig. 33b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 33c). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 33d). Coenenchyme with capstans (Fig. 34a), and unilaterally spinose spheroids, 0.05–0.10 mm long (Fig. 34b). Furthermore spindles are present, 0.10–0.25 mm long (Fig. 34c). All with simple and complex tubercles. The calyces with additional leaf clubs, up to 0.20 mm long (Fig. 33f). The axis has smooth and sparsely tuberculate rods (Fig. 33e).

Figure 33.

Sclerites of Melithaea isonoi sp. n., UMUTZ-CnidG-34; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod; f clubs of calyx.

Figure 34.

Sclerites of Melithaea isonoi sp. n., UMUTZ-CnidG-34; a capstans b unilaterally spinose spheroids c spindles of coenenchyme.

Color

The colony is orange as are most sclerites; a few are yellow colored.

Distribution

Only known from Okinawa Prefecture (Fig. 35). The material is probably collected during the Ryukyu (= Okinawa) expedition by K. Mitsukuri and I. Ikeda, in April, 1901.

Figure 35.

Distribution of Melithaea doederleini sp. n. (*), Melithaea frondosa (●), and Melithaea isonoi sp. n. (■).

Etymology

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.

Remarks

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 Aguilar-Hurtado et al. (2012), but in that case we must accept that these authors did not illustrate the remarkable unilaterally spinose spheroids that we found among the sclerites. The “spines” of these spheroids are very rounded, hardly resembling spines. However, a more appropriate term than spinose spheroids is not available (Bayer et al. 1983). Moreover, all colonies of Aguilar-Hurtado et al. (2012) had anastomoses while M. isonoi has none.

Melithaea japonica (Verrill, 1865)

Figures 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55

Mopsella japonica: Verrill 1865: 190; Verrill 1870: 80 (Simoda (=Shimoda), Japan).

Melitella japonica: Gray 1870: 7.

? Acabaria japonica: Ridley 1884: 361 (Darwin, Australia).

Acabaria japonica (in part): Kükenthal 1919: 188; 1924: 82.

Acabaria japonica: Hickson 1937: 178 (re-examination of type).

Pleurocorallium confusum: Moroff 1902a: 582; Moroff 1902b: 404, pl. 17 fig. 8, pl. 18 fig. 19.

Pleurocoralloides confusum: Kükenthal 1924: 53.

Pleurocoralloides formosum: Moroff 1902a: 583; Moroff 1902b: 406, pl. 17 fig. 10, pl. 18 fig. 20; Kükenthal 1924: 52, fig. 42.

Melitodes flabellifera: Kükenthal 1908: 190; Kükenthal 1909: 54, figs 50–54, pl. 4 fig. 22 (Japan); Kükenthal 1919: 143; 1924: 58; Aurivillius 1931: 23 (Sagami Bay); Hickson 1937: 122.

M. flabellifera var. reticulata: Kükenthal 1908: 191; Kükenthal 1909: 55, pl. 4 fig. 23; Kükenthal 1924: 59.

M. flabellifera var. cylindrata: Kükenthal 1908: 192; Kükenthal 1909: 57, pl. 4 fig. 24; Kükenthal 1924: 59.

Melitodes densa Kükenthal 1908: 192; 1909: 58, figs 59–60, pl. 5 fig. 25 (Japan); 1919: 143; 1924: 58; Hickson 1937: 122.

?Melithaea flabellifera: Rho et al. 1980: 48 (Korea Strait); Song 2000: 111 (Korea Strait, Sea of Japan).

?Melithaea densa: Rho et al. 1980: 50 (Korea Strait); Song 2000: 114 (Korea Strait).

Material examined

Holotype of Mopsella japonica BMNH 1946.1.14.207 dried sclerites of the type MCZ 4265, now MCZ Invertebrate Zoology ALCY-412 (microscopic slide only), Simoda (= Shimoda), Japan, coll. Prof. Hickson; NHMW 8046 (A.N. 1156), Nagasaki, Japan, I. Erber in Wien (Dr. A. v. Roretz) (possibly collected between ca.1875–1879); NHMW 8047, Enoshima, Japan, coll. Dr. Richard. v. Drasche; NHMW 12690 (A.N. 4837), Enoshima, Japan, Baron Eug. V. Ransonnet, Ostasiatisches Ex. (1873); Pleurocoralloides formosum, ZSM 20051735, type, Japan, Sagami Bay, leg. Haberer, 1901; Melitodes flabellifera: ZMB 5822, syntype, Japan, up to 20 m depth, coll. Doflein, 1904/05; NHMW 2426, Enoshima, Nagoya, coll. Drasche, Koerbl, 18–19 December 1877; MZS-Cni52, Sagami Bay, coll. Doederlein, 1882; BMNH 1936.7.6.7, Sagami Channel, Sagami Bay, purchased of Shibayama Nat. Sci. Laboratory Cat. No. 7c-7A, 7 August 1931; Melitodes densa: ZMB 5801, syntype, Sagami Bay, 60–250 m?, coll. Doflein 1904/05; ZMB 5809, syntype, Sagami Bay, littoral, coll. Doflein1904/05; previously unidentified museum material: BMNH 1883.8.29.10, Enoshima, Japan, coll. Res. by D?.F.J. Burge; MZS-Cni 235, Jogashima, Sagami Bay, Japan, coll. Doederlein; ZMUC ANT-000591, Misaki, Sagami Bay, Japan, 1–2 fms (2–4 m), coll. Dr. Th. Mortensen, 24 June 1914; UMUTZ-CnidG- 257 (G-23b), gorgonia cave at Koajiro, Misaki, Sagami Bay, 16 July 1897; UMUTZ-CnidG-258 (G-23c), same data as UMUTZ-CnidG-257 (G-23b); UMUTZ-CnidG-259 (G-23d), same data as UMUTZ-CnidG-257 (G-23b); UMUTZ-CnidG-35, Misaki, Sagami Bay, Japan sp. no. 19; UMUTZ-CnidG-260 (G-35b), same data as UMUTZ-CnidG-35; UMUTZ-CnidG-261 (G-35c), same data as UMUTZ-CnidG-35; UMUTZ-CnidG-262 (G-35d), same data as UMUTZ-CnidG-35; UMUTZ-CnidG-36, Misaki, Sagami Bay, Japan; UMUTZ-CnidG-263 (G-36b), same data as UMUTZ-CnidG-36; UMUTZ-CnidG-264 (G-36c), same data as UMUTZ-CnidG-36; UMUTZ-CnidG-265 (G-36d), same data as UMUTZ-CnidG-36; UMUTZ-CnidG-37, Misaki, Sagami Bay, Japan, coll. K. Kinoshita, summer 1906; UMUTZ-CnidG-266 (G-37b), same data as UMUTZ-CnidG-37; UMUTZ-CnidG-267 (G-37c), same data as UMUTZ-CnidG-37; UMUTZ-CnidG-269 (G-37e), same data as UMUTZ-CnidG-37; UMUTZ-CnidG-38, Cape Makurazaki, Kagoshima Prefecture, coll. M. Miyajima by diving, 7 August 1899; UMUTZ-CnidG-42, Misaki, Sagami Bay, Japan, 1–5 April 1917; UMUTZ-CnidG-272 (G-42b), same data as UMUTZ-CnidG-42; UMUTZ-CnidG-43, Misaki, Sagami Bay, Japasp. n. no. 77; UMUTZ-CnidG-273 (G-43b), same data as UMUTZ-CnidG-43; UMUTZ-CnidG-274 (G-43c), same data as UMUTZ-CnidG-43; UMUTZ-CnidG-275 (G-43d), same data as UMUTZ-CnidG-43; UMUTZ-CnidG-276 (G-43e), same data as UMUTZ-CnidG-43; UMUTZ-CnidG-44, Shimoda Harbour, Izu Peninsula, Japan, vessel Ohnoura-maru cruise, coll. S. Hirota, 28 August 1893; UMUTZ-CnidG-277 (G-44b), same data as UMUTZ-CnidG-44; UMUTZ-CnidG-278 (G-44c), same data as UMUTZ-CnidG-44; UMUTZ-CnidG-116, near Misaki Marine biological Station, Sagami Bay, Japan, coll. I. Ijima by diving, 1913; UMUTZ-CnidG-192, Moroiso, Misaki, Sagami Bay, Japan, collected by diving, 12 August 1904; UMUTZ-CnidG-196, Shimo-Chikura, Kagoshima Prefecture, Japan, coll. M. Miyajima by coral net, 12 July 1899; AKM 1633, Kominato, Japan, April 1944, deposited in Aikappu Museum of Natural History, Akkeshi Marine Station, Field Science Center for Northern Biosphere Hokkaido University; BIK-G224, Saba-shima Is. Koga Bay, Oga Peninsula, Sea of Japan, 7 m, coll. Y. Sato. 14 July 1988; BIK-G226, same data as BIK-G224; RMNH Coel. 41914 (AKM 594), Entrance of Otsuchi Bay, Otsuchi, Iwate Prefecture, 39°21.858'N, 141°59.972'E, 65.6 m, R/V Yayoi, coll. A.K. Matsumoto, 12 September 2005; RMNH Coel. 41915 (AKM 614), same data as RMNH Coel.41914; RMNH Coel. 41916 (AKM 615), Entrance of Otsuchi Bay, Iwate Prefecture, 39°21.917'N, 142°00.031'E, 77.6 m, R/V Yayoi, St.1(=St.2) 1 m biological dredge, coll. A.K. Matsumoto, 12 September 2005; RMNH Coel. 41917 (AKM 618), same data as RMNH Coel.41916; RMNH Coel. 41918 (AKM 619), off Ohako-zaki Cape, Otsuchi Bay, Iwate Prefecture, 39°21.428'N, 142°00.520'E, 69.2 m, R/V Yayoi, St.2(=St.5), 1 m biological dredge, coll. A.K. Matsumoto, 12 September 2005; RMNH Coel. 41919 (AKM 622), same data as RMNH Coel.41918; RMNH Coel. 41920 (AKM 1200), off Ohako-zaki Cape, Otsuchi Bay, Iwate Prefecture, ca. 39°21'N, 142°00'E, ca. 90 m, local fishery boat Taku-maru, gill-net, coll. K. Morita, ca. 21 March 2008; RMNH Coel. 41921 (AKM 1201), same data as RMNH Coel.41920; RMNH Coel. 41922 (AKM 1204), off Ohako-zaki Cape, Otsuchi Bay, Iwate Prefecture, ca. 39°21'N, 142°00'E, ca. 90 m, local fishery boat Taku-maru, gill-net, coll. K. Morita, 2 May. 2008; RMNH Coel. 41923 (AKM 1252), off Ohako-zaki Cape, Otsuchi Bay, Iwate Prefecture, ca. 39°21'N, 142°00'E, ca.75 m, local fishery boat Taku-maru, gill-net, coll. K. Morita, 9 May 2008; RMNH Coel. 41924 (AKM 1526), off Oshima Is. Entrance of Otsuchi Bay and Funakoshi Bay, Iwate Prefecture, 39°22.085'N, 142°01.152'E, 97 m, R/V Yayoi, 1 m biological dredge, coll. A.K. Matsumoto, 26 April 2010.

Re-description

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. 38a). Collaret with bent spindles up to 0.25 mm long, middle part with more developed tubercles. Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 38b). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.05 mm long. Coenenchyme with capstans (Fig. 38c), 0.07–0.08 mm long and small clubs of similar length (Fig. 38d). Furthermore spindles (Fig. 38e), unilaterally spinose spindles (Fig. 38f) and unilaterally spinose spheroids (Fig. 38g) are present, 0.10–0.30 mm long. All with simple and complex tubercles. The calyces with additional clubs, up to 0.20 mm long (Fig. 38h). The axis has smooth and sparsely tuberculate rods (Fig. 38i).

Figure 36.

Melithaea japonica; a Pleurocoralloides formosum, ZSM 20051735 b Melitodes flabellifera ZMB 5822 c Melitodes densa, ZMB 5801 d Melitodes densa, ZMB 5809 e Melitodes falbellifera, NHMW 2426.

Figure 37.

Melithaea japonica; a BIK-G 224 b NHMW 8047 c RMNH Coel. 41922.

Figure 38.

Sclerites of Melithaea japonica, BMNH 1946.1.14.207; a point spindles b tentacle sclerite c capstans d clubs of coenenchyme e spindles f unilateraly spinose spindle g unilaterally spinose spheroids h club of calyx; i, axial rod.

Color

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. RMNH Coel. 41923 is rather unique in having a pale light brown colony, tentacle sclerites colorless, others colorless, partly white and partly yellow, or entirely yellow.

Distribution

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. 55).

Remarks

The examined type material of Mopsella japonica was fragmented. In Harvard we only found one microscope slide (MCZ 4265, ALCY-412), in London only dried sclerites of the Harvard material (BMNH 1946.1.14.207). The type colony seems to be lost. Only in Vienna we found complete specimens identified as M. japonica; NHMW 8046, NHMW 8047 (Fig. 37b) and NHMW12690 identified as M. japonica, the sclerites resemble those of the type material (Figs 39, 40). The collector of NHMW 8046, Dr. Albrecht von Roretz visited Japan as a medical attaché of Austria (= Hungarian legation) between 1875–1879 and possibly collected this material. NHMW 2426 (M. flabellifera) and NHMW 8047 were collected by Dr. Richard. v. Drasche. He visited Japan during the Far East expedition 1875–1876. The Ostasiatisches Expedition by Baron Eug. V. Ransonnet, during which NHMW 12690 was collected, happened in 1873 (Matsumoto 2013, submitted).

Figure 39.

Sclerites of Melithaea japonica, NHMW 8047; a point spindle b collaret spindles c tentacle sclerites d pharynx rods e capstans f clubs of coenenchyme g clubs of calyx.

Figure 40.

Sclerites of Melithaea japonica, NHMW 8047; a clubs of calyx b capstans c unilaterally spinose spheroids d unilaterally spinose spindle e spindles.

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, Kükenthal (1908) mentioned 40 specimens for his Melitodes flabellifera. We examined ZMB 5822 (Figs 36b, 41, 42) and NHMW 2426 (Figs 36e, 43, 44). They both are similar to M. japonica.

Figure 41.

Sclerites of Melitodes flabellifera, ZMB 5822; a point spindle b collaret spindle c tentacle sclerites d pharynx rods e unilaterally spinose spheroids f unilaterally spinose spindle.

Figure 42.

Sclerites of Melitodes flabellifera, ZMB 5822; a capstans b spindles c clubs of coenenchyme d clubs of calyx.

Figure 43.

Sclerites of Melitodes flabellifera, NHMW 2426; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e unilaterally spinose spheroids.

Figure 44.

Sclerites of Melitodes flabellifera, NHMW 2426; a spindles b unilaterally spinose spindle c clubs of coenenchyme d clubs of calyx.

M. densa is also reported to occur in shallow water. According to Kükenthal (1909) it resembles M. flabellifera very much but differs in having more spinose collaret and point sclerites, more densely, stronger ornamented coenenchymal sclerites, and the color always being red with yellow polyps. Later, he separated the two species with M. densa having no clubs (Kükenthal 1924). The ZMB 5801 colony examined by us (Fig. 36c) showed many disintegrated sclerites (Figs 45, 46). As this mostly concerned the smaller sclerites we were unable to show the capstans and small clubs. But we found a few larger calyx clubs, apparently overlooked by Kükenthal (1909). Also most point sclerites were badly damaged. We also examined ZMB 5809 (Fig. 36d), which had its sclerites less disintegrated (Figs 47, 48).

Figure 45.

Sclerites of Melitodes densa, ZMB 5801; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rods f unilaterally spinose spheroids g unilaterally spinose spindles.

Figure 46.

Sclerites of Melitodes densa, ZMB 5801; a spindles of coenenchyme b clubs of calyx.

Figure 47.

Sclerites of Melitodes densa, ZMB 5809; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e clubs of calyx.

Figure 48.

Coenenchymal sclerites of Melitodes densa, ZMB 5809; a capstans b unilaterally spinose spheroids c unilaterally spinose spindles d spindles.

Kükenthal (1924: 53) referred Pleurocorallium confusum to Pleurocoralloides. Bayer and Cairns (2003: 222) suggested that the species belongs to Acabaria. Moroff (1902a, b), in his descriptions of the species, mentioned flattened branches; polyps on one side of the colony; sclerites straight or bent 0.25 mm long spindles; also plate-like sclerites and crosses present; colony red with yellow polyps. The type seems to be lost. Because of its flattened branches we consider P. confusum synonymous with M. japonica.

Bayer and Cairns (2003: 222) suggested Pleurocoralloides formosum to belong to Acabaria. It was described as having polyps with 7 spindles per point and 6 rows in the collaret; sclerites orange, tentacles ones yellow, axis orange. We consider it a synonym of M. japonica; the colonies are shown in Fig. 36a, its sclerites are depicted in Figs 49, 50.

Figure 49.

Sclerites of Pleurocoralloides formosum, ZSM 20051735; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e capstans f unilaterally spinose spheroids.

Figure 50.

Sclerites of Pleurocoralloides formosum, ZSM 20051735 a clubs of calyx b spindles of coenenchyme.

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, SMF 1260 and 1262, but we could not find these specimens during a visit.

In northern Japan we found quite a number of specimens: RMNH Coel. 41915–41924. As an example we show the colony of RMNH Coel. 41922 (Fig. 37c) and its sclerites (Figs 51, 52). Here, the smallest colonies are white or yellow, only RMNH Coel. 41922 is red.

Figure 51.

Sclerites of Melithaea japonica, RMNH Coel. 41922; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs of coenenchyme f clubs of calyx g capstans h unilaterally spinose spheroids.

Figure 52.

Coenenchymal sclerites of Melithaea japonica, RMNH Coel. 41922.

We found three specimens with extreme slender sclerites: BIK-G224 (Fig. 37a; sclerites Figs 53, 54), BIK-G226, and RMNH Coel. 41914.

Figure 53.

Sclerites of Melithaea japonica, BIK-G224; a point spindle b collaret spindles c tentacle sclerites d pharynx rod e axial rods f clubs of coenenchyme g clubs of calyx.

Figure 54.

Sclerites of Melithaea japonica, BIK-G224; a unilaterally spinose spheroids b capstans c unilaterally spinose spindles d spindles.

Figure 55.

Distribution of Melithaea japonica (*), north M. japonica (●), and slender M. japonica (■).

Melithaea keramaensis sp. n.

Figures 56a, 57, 58, 65

Material examined

Holotype RMNH Coel. 41925 (AKM 1148), off Kerama Isls., Okinawa Prefecture, Japan, 26°09.45'N, 127°26.90'E26°09.65'N, 127°26.81'E, 85–71 m, R/V Tansei-maru, KT08-33, St. KR-09, Chain Bag Dredge, coll. A.K. Matsumoto, 15 December 2008; paratype RMNH Coel. 41926 (AKM 1139), off Kerama Isls., Okinawa Prefecture, Japan, 26°12'N, 127°30'E, 56–51 m, R/V Tansei-maru, KT08-33, st. KR-10, coll. A.K. Matsumoto, 15 December 2008.

Description

The holotype is a 12 cm long fragment without holdfast (Fig. 56a). At the base the stem is 1 cm wide, the end branches are only 1 mm wide. The polyps are situated laterally on the branches, the calyces hardly project beyond the coenenchyme and most polyps are retracted. Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig. 57a). Collaret with bent spindles up to 0.25 mm long, middle part with more developed tubercles (Fig. 57b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 57c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 57d). Coenenchyme with predominantly capstans (Fig. 57e), double disks (Fig. 57h), and small clubs (Fig. 57f), 0.05–0.08 mm long. Spindles (Fig. 58a) and disk spindles (Fig. 58b) are also common, 0.10–0.15 mm long. The calyces with additional leaf clubs, up to 0.15 mm long (Fig. 58c).

Figure 56.

a Melithaea keramaensis sp. n., RMNH Coel. 41925, holotype b M. modesta, ZMB 5807, syntype c M. mutsu SMBL-Cni1017.

Figure 57.

Sclerites of Melithaea keramaensis sp. n., RMNH Coel. 41925; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod f clubs of coenenchyme g capstans h double disks.

Figure 58.

Sclerites of Melithaea keramaensis sp. n., RMNH Coel. 41925; a spindles b disk spindles, the top four seen from the underside c clubs of calyx.

Color

Colony red with white calyces and polyps. Coenenchymal sclerites orange, calyx and polyp sclerites colorless.

Variation

The paratype is very much alike the holotype regarding color and sclerites.

Distribution

The species is only known from the Kerama Islands (Fig. 65).

Etymology. The species is named after its type locality, the Kerama islands.

Remarks

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.

Melithaea modesta (Kükenthal, 1908)

Figures 56b, 59, 60, 61, 62, 65

Acabaria modesta Kükenthal 1908: 197; 1909: 66, figs 73–75, pl. 5 fig. 30 (Sagami Bay, Japan); 1919: 183; 1924: 79; Hickson 1937: 181.

Not Melithaea modesta (Nutting, 1911) = Melithaea planoregularis (Kükenthal, 1910).

Material examined

Syntype ZMB 5807, Sagami Bay (Japan), 80-250 m (label 600 m), coll. Doflein 1904/05; previously unidentified museum material: ZMUC ANT-000595, Okinose, Sagami Sea, 60 fms (86–110 m), coll. Dr. Th. Mortensen, 11 June 1914; ZMUC ANT-000649, same data as ZMUC ANT-000595; UMUTZ-CnidG-19, Kashiwa-jima Is. Tosa, Kochi Prefecture, Japan, probably collected by K. Kinoshita during his Kashiwa-jima Is. Coral Ground Expedition, June 1909; UMUTZ-CnidG-27, coral ground, Uji Isls. Satsuma, Kanogshima Prefecture, Japan, ca. 80 fms (114–121 m), Kinoshita leg. coll. K. Kinoshita, June 1908; AKM 443, Sakai Port, Minabe, Wakayama Prefecture, ca.33°7445'N, 135°3329'E, shallower than 100 m, lobster-net, coll. A.K. Matsumoto, 1 April 2003; AKM 572, Otsuki, Tosa, Kochi Prefecture, 32°43'N, 132°48'E, 84.75-83.1 m, local fishermen’s boat, Kiryo-maru, coral net, st. 3, coll. A.K. Matsumoto, 7 October 2004; AKM 740, off Sata-misaki Cape, Kagoshima Prefecture, 31°00.50'N, 130°35.09'E31°01.3211'N, 130°34.6509'E, 178-189 m, R/V Tansei-maru, KT07-1, st. SM-2, coll. A.K. Matsumoto, 23 February 2007; AKM 904, Hachijo Is. Izu Isls., 33°20.9082'N, 139°41.1841'E33°21.0775'N, 139°40.4931'E, 213-185 m, R/V Tansei-maru, KT07-31, st. 14, coll. A.K. Matsumoto, 26 November 2007; AKM 1575, Takase west, Izu Is., Japan, ca. 34°21'N, 138°52'E34°26'N, 139°07'E, 221–244 m, R/V Tansei-maru, KT-87-19 cruise, St. TW02, large cylindrical dredge, coll. Suguru Ohta, 8 December1987; AKM 1594, SE off Taito-Saki, Boso, Chiba Prefecture, 35°05.086'N, 140°51.718'E35°04.176'N, 140°50.921'E, 975–1027 m, R/V Tansei-maru, KT03-17, St. TS6-3, 3 m ORE beam trawl, coll. Suguru Ohta, 17 November 2003; AKM 1601, Otsuki, Tosa, Kochi pref., 32°37.66'N, 132°50.44'E32°37.56'N, 132°47.88'E, 114 m, local fishermen’s boat, Kiryo-maru, St.1, coll. A.K. Matsumoto, 7 October 2004.

Re-description

Colony branched in one plane with few anastomoses (Fig. 56b). Points with slightly bent spindles up to 0.25 mm long, distal end with more developed tubercles (Fig. 59a). Collaret with bent, rather smooth spindles up to 0.30 mm long, middle part with tubercles (Fig. 59b). Tentacles with platelets, the larger ones crescent-shaped (Fig. 59c). These platelets are up to 0.18 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 59d). Coenenchyme with spindles 0.10–0.25 mm long (Fig. 60), with simple or complex tubercles. The axis has smooth and sparsely tuberculate rods (Fig. 59e).

Figure 59.

Sclerites of Melithaea modesta, ZMB 5807, syntype; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e axial rod.

Figure 60.

Coenenchymal sclerites of Melithaea modesta, ZMB 5807, syntype.

Color

Colony white, sclerites colorless.

Variation

ZMUC ANT-000649 showed somewhat longer spindles, up to 0.40 mm long (Figs 61, 62).

Figure 61.

Sclerites of Melithaea modesta, ZMUC ANT-000649; a point spindles b collaret spindle c tentacle sclerites d pharynx rods e coenenchymal spindles.

Figure 62.

Coenenchymal sclerites of Melithaea modesta, ZMUC ANT-000649.

Distribution

Pacific side of Japan (Fig. 65); northern limit is Sagami Bay.

Remarks

The species is easily recognized by its white colony color, rather smooth polyp sclerites, and presence of spindles only.

Melithaea mutsu Minobe, 1929

Figures 56c, 63, 64, 65

Melithaea mutsu Minobe 1929: 671, figs 1–2 (Mutsu Bay, Japan).

Material examined

Neotype SMBL-Cni1017, Sai, Mutsu Bay, Aomori Prefecture, close to Tsugaru Straits between Sea of Japan and NW Pacific, 5 m, coll. M. Nishihira and Hoshiai, 13 August 1964.

Description

Colony broken up, consisting of three fragments, bushy with few anastomoses. The largest fragment is 7.3 cm long without holdfast (Fig. 56c). At the base the stem is 7 mm wide, the end branches are 2 mm wide. The polyps are arranged randomly, the calyces hardly project beyond the coenenchyme and most polyps are retracted. Points with slightly bent spindles up to 0.30 mm long, distal end with more tubercles (Fig. 63a). Collaret with bent spindles up to 0.30 mm long, middle part with tubercles (Fig. 63b). Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 63c). Coenenchyme with predominantly spindles, 0.10–0.25 mm long (Figs 63f, 64), with simple or complex tubercles. Capstans are also present, 0.05–0.10 mm long (Fig. 63e). The axis has smooth and sparsely tuberculate rods (Fig. 63d).

Figure 63.

Sclerites of Melithaea mutsu, SMBL-Cni1017, neotype; a point spindles b collaret spindles c pharynx rod d axial rods e capstans f coenenchymal spindles.

Figure 64.

Coenenchymal sclerites of Melithaea mutsu, SMBL-Cni1017, neotype.

Color

Colony red, sclerites orange.

Distribution

Only known from the northern tip of the main island of Japan, Honshu Is. (Fig. 65).

Figure 65.

Distribution of Melithaea keramaensis sp. n. (*), M. modesta (●), and M. mutsu (■).

Remarks

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.

Melithaea nodosa Wright & Studer, 1889

Figures 66a–c, 67, 68, 69, 74

Melitodes nodosa: Wright and Studer 1889: 178, pl. 40 fig. 10 (off New Hebrides, Hyalonema Ground Japan); Kükenthal 1919: 141; 1924: 57.

Acabaria nodosa: Hickson 1937: 178.

Not Melitodes nodosa: Thomson 1911: 876 (South Africa).

Material examined

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.

Re-description

BMNH 89.5.27.117 (Fig. 66b): Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig. 67a). Collaret with bent spindles up to 0.25 mm long, middle part with more developed tubercles (Fig. 67b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 67c). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.035 mm long (Fig. 67d). Coenenchyme with spindles (Fig. 67e) and unilaterally spinose spindles (Fig. 67f), 0.08-0.23 mm long, with simple tubercles. The calyces with additional clubs, up to 0.20 mm long (Fig. 67g).

Figure 66.

a Melithaea nodosa, BMNH 1947.3.22.6 b BMNH 89.5.27.117 c BMNH 89.5.27.118 d M. oyeni sp. n., RMNH Coel. 41927 e M. ryukyuensis sp. n., UMUTZ-CnidG-32.

Figure 67.

Melithaea nodosa, BMNH 89.5.27.117; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e coenenchymal spindles f unilaterally spinose spindles g clubs of calyx.

Color

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.

Variation

BMNH 89.5.27.118 (Figs 66c; 68) and BMNH 1947.3.22.6 (Fig. 66a) have similar color patterns, BMNH 1947.3.22.6 has wider coenenchymal sclerites (Fig. 69).

Figure 68.

Melithaea nodosa, BMNH 89.5.27.118; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e coenenchymal spindles f unilaterally spinose spindles g clubs of calyx.

Figure 69.

Melithaea nodosa, BMNH 1947.3.22.6; a point spindles b collaret spindles c tentacle sclerites d coenenchymal spindles e unilaterally spinose spindles f clubs of calyx.

Distribution

New Hebrides, Sagami Bay (Fig. 74).

Remarks

Wright and Studer (1889) mentioned that the colony may have been about 130 mm in height and 60 to 80 mm in diameter. Only BMNH 89.5.27.117 has this size (Fig. 66b), BMNH 89.5.27.118 is much smaller (Fig. 66c), BMNH 1947.3.22.6 consists of only a few fragments (Fig. 66a). Based on these colony sizes we conclude that these authors used BMNH 89.5.27.117 for their description.

Melithaea oyeni sp. n.

Figures 66d, 70, 71, 74

Material examined

Holotype RMNH Coel. 41927 (AKM 408), Watari-se bank, off Izu Isls., 34°02.8620'N, 138°54.8090'E34°02.9190'N, 138°54.6810'E, 101.1-106.2 m, R/V Tansei-maru, KT04-06 cruise, St.WS-2, 1m ORI Dredge, coll. A.K. Matsumoto, 30 April 2004; paratype RMNH Coel. 41928 (AKM 1606), Takase West, Izu Ridge, 34°26.5'N, 139°07.2'E, 104–127 m, R/V Tansei-maru, KT87-19, St. TW1, coll. S. Ohta, 8 December 1987.

Description

The holotype is a 8 cm long fragment with holdfast (Fig. 66d). At the base the stem is 3 mm wide, the end branches are only 1 mm wide. The polyps are situated bilaterally on the branches, the calyces are dome-shaped, and most polyps are expanded. Points with slightly bent spindles up to 0.20 mm long, distal end with leaves (Fig. 70a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 70b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 70c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 70d). Coenenchyme with predominantly capstans, double disks (Fig. 70f) and disk spindles (Figs 70g, 71c), 0.05–0.15 mm long, and small clubs (Fig. 71a), up to 0.10 mm long. Spindles are also present, 0.10-0.25 mm long, with simple tubercles (Fig. 71d). The calyces with additional clubs, up to 0.15 mm long (Fig. 71b).

Figure 70.

Melithaea oyeni sp. n., RMNH Coel. 41927; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod f double disks g disk spindles.

Figure 71.

Melithaea oyeni sp. n., RMNH Coel. 41927; a clubs of coenenchyme b clubs of calyx c disk spindles d spindles.

Color

Colony orange with yellow polyps, coenenchymal sclerites orange, polyp ones yellow.

Variation

RMNH Coel. 41928 has similar sclerites and color.

Distribution

Off the Izu Islands (Fig. 74)

Etymology

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.

Remarks

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. 70f with Fig. 3b).

Melithaea ryukyuensis sp. n.

Figures 66e, 72, 73, 74

Melithaea sp. A: Aguilar-Hurtado et al. 2012: 62, fig. 5 (Okinawa).

Material examined

Holotype UMUTZ-CnidG-32, Nakagusuku Bay, Okinawa Prefecture, Japan, diving, 16 April 1901; paratypes, UMUTZ-CnidG-254, same data as holotype; UMZC I.36300, S.W. Japan. T. Mizobuchi (purchased). Reg. Jan. 31.1903, 16.

Description

The holotype is a 14.5 cm long fragment without holdfast (Fig. 66e). At the base the stem is 15 mm wide, the end branches are only 1 mm wide. The polyps are situated on one side of the colony, the calyces hardly project beyond the coenenchyme, and most polyps are retracted. Points with slightly bent spindles up to 0.10 mm long, distal end with more developed tubercles (Fig. 72a). Collaret with bent spindles up to 0.15 mm long, middle part with more developed tubercles (Fig. 72b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 72c). These platelets are up to 0.10 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 72d). Coenenchyme with predominantly capstans (Fig. 73a, d), double disks (Fig. 73b) and disk spindles (Fig. 73c), 0.05–0.10 mm long, and small clubs with rounded heads, 0.05 mm long (Fig. 72f). Spindles are also present, 0.10–0.20 mm long, with complex tubercles (Fig. 73e). The calyces with additional clubs, up to 0.14 mm long (Fig. 72g). The axis has smooth and sparsely tuberculate rods (Fig. 72e).

Figure 72.

Melithaea ryukyuensis sp. n., UMUTZ-CnidG-32; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e axial rod; f clubs of coenenchyme g clubs of calyx.

Figure 73.

Melithaea ryukyuensis sp. n., UMUTZ-CnidG-32; a captans b double disks c disk spindles d irregular capstan e spindles.

Color

Colony orange with yellow polyps. Part of calyx sclerites and all polyp sclerites yellow, all others orange.

Distribution

Okinawa, Japan (Fig. 74).

Figure 74.

Distribution of Melithaea nodosa (*), M. oyeni sp. n. (●), and M. ryukyuensis sp. n. (■).

Remarks

The material of UMUTZ-CnidG-32 was probably collected during the Ryukyu (= Okinawa) expedition by K. Mitsukuri and I. Ikeda, in April, 1901. UMZC I.36300 is dried material. According to us this is Melithaea sp. A of Aquilar-Hurtado et al. (2012) as the sclerite images given by them resemble ours. Melithaea ryukyuensis mostly resembles M. abyssicola, which has overall larger sclerites but much smaller spindles in the coenenchyme.

Melithaea sagamiensis sp. n.

Figures 75a–b, 76, 77, 78, 79, 80, 81, 86

Material examined

Holotype RMNH Coel. 41929 (AKM 840a), East of Jogashima Spur, 35°03.52'N, 139°37.43'E35°04.17'N, 139°37.52'E, 397–286 m, R/V Tansei-maru, KT07-31, st.8, coll. A.K. Matsumoto, 25 November 2007; paratypes: ZMUC ANT-000657, Sagami Bay, Okinose, 200 fms (286–366 m), Coll. Mortensen, 1 July 1914; ZMUC ANT-000660, same data as ZMUC ANT-000657; RMNH Coel. 41930 (AKM 243), South of Mera-se-minami Knoll, Sagami Bay, 34°54.8'N, 139°39.7'E34°54.8'N, 139°39.9'E, 312–348 m, R/V Shinyo-maru, St. 10, coll. A.K. Matsumoto, 18 October 2003; RMNH Coel. 41931 (AKM 244), same data as RMNH Coel. 41930; RMNH Coel. 41932 (AKM 247), South of Mera-se Minami Knoll, 34°54.8'N, 139°39.7'E34°54.8'N, 139°39.9E, 315-365 m, R/V Shinyo-maru, coll. A.K. Matsumoto, 18 October 2003; RMNH Coel. 41933 (AKM 593), Entrance of Otsuchi-bay, Iwate Prefecture, 39°21.858'N, 141°59.972'E, 65.6 m, R/V Yayoi, 1 m biological dredge, coll. A.K. Matsumoto, 12 September 2005; RMNH Coel. 41934 (AKM 835), Off Sendai, Miyagi Prefecture, depth over 100 m, trawl, coll. Hagihara, June 2007; RMNH Coel. 41935 (AKM 1605), West off Izu-Oshima, Sagami Sea, 410–440 m, R/V Hakuho-maru, KH-78-05, st. BS8, 2 m S.-A. beam trawl, coll. S. Ohta, 9 December 1978; BMNH 62.7.16.62(61?), off Okushiri Is., 3 miles off shore, Sea of Japan, 41°59'N, 138°30'E, 25-30 feet.

Description

The holotype (RMNH Coel. 41929) consists of a number of branches probably belonging to one colony broken up while collecting (Fig. 75a). The largest fragment is 2.8 cm long. A holdfast or anastomoses are not present. The polyps are situated on one side of the colony. The calyces are dome-shaped, about 0.5 mm high and 1 mm wide; most polyps are retracted. Points with slightly bent spindles up to 0.25 mm long, distal end with more developed tubercles (Fig. 76a). Collaret with bent spindles up to 0.40 mm long, middle part with more developed tubercles (Fig. 76b). Tentacles with platelets, the larger ones crescent-shaped (Fig. 76c). These platelets are up to 0.15 mm long and have almost no tuberculation. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 76d). Coenenchyme with capstans 0.05-0.07 mm long, unilaterally spinose spindles (Fig. 77b), small clubs of the same length as the capstans, and spindles 0.10-0.20 mm long (Fig. 77a); all with simple tubercles. The calyces with additional leaf clubs, up to 0.15 mm long (Fig. 76e).

Figure 75.

a Melithaea sagamiensis sp. n., RMNH Coel. 41929 b RMNH Coel. 41931 c M. satsumaensis sp. n. RMNH Coel. 41936 d M. suensoni sp. n. ZMUC ANT-000565.

Figure 76.

Sclerites of Melithaea sagamiensis sp. n., RMNH Coel. 41929; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs of calyx.

Figure 77.

Sclerites of Melithaea sagamiensis sp. n., RMNH Coel. 41929; a spindles b unilaterally spinose spindles.

Color

White, all sclerites colorless.

Variation

The paratypes are also fragmented. RMNH Coel. 41930, ZMUC ANT-000657 and ZMUC ANT-000651 are also white. ZMUC ANT-000660, RMNH Coel. 41931 and RMNH Coel. 41932 are yellow with yellow sclerites. BMNH 62.7.16.62(61?), RMNH Coel. 41934 and RMNH Coel. 41933 came from northern Japan, all three being red and from shallower depth. RMNH Coel. 41931 has somewhat more developed sclerites (Figs 78, 79).

Figure 78.

Sclerites of Melithaea sagamiensis sp. n., RMNH Coel. 41931; a point spindles b collaret spindle c tentacle sclerites d pharynx rod e clubs of coenenchyme f clubs of calyx.

Figure 79.

Sclerites of Melithaea sagamiensis sp. n., RMNH Coel. 41931; a unilaterally spinose spindles b spindles.

Distribution

Pacific side of Japan; Sagami Bay, off Sendai (Miyagi Prefecture), Otsuchi Bay (Sanriku, Iwate Prefecture); and Sea of Japan side, off Okushiri Is. (Fig. 86).

Etymology

The species is named after the type locality, Sagami Bay.

Remarks

We included BMNH 62.7.16.62(61?) in Melithaea sagamiensis sp. n. despite its slightly different sclerites (Figs 80, 81). We were not certain about the collection number, hence the “62(61)?”.

Figure 80.

Sclerites of Melithaea sagamiensis sp. n., BMNH 62.7.16.62(61?); a point spindles b collaret spindles c tentacle sclerites d pharynx rod e capstans f clubs of calyx.

Figure 81.

Sclerites of Melithaea sagamiensis sp. n., BMNH 62.7.16.62(61?); a unilaterally spinose spindles b spindles.

Melithaea satsumaensis sp. n.

Figures 75c, 82, 83, 86

Material examined

Holotype RMNH Coel. 41936 (AKM 743), Off Sata-misaki Cape, Kagoshima Prefecture, Japan, 30°56.0025'N, 130°44.2299'E30°56.2953'N, 130°43.3981'E, 116-120 m, R/V Tansei-maru, KT07-1 cruise, St. SM-1, Chain Bag Dredge, coll. A.K. Matsumoto, 23 February 2007.

Description

The holotype is a 16.5 cm long colony with holdfast (Fig. 75c). At the base the stem is 10 mm wide, the end branches are only 1 mm wide. On the lower half of the colony the polyps are situated on one side of the colony; the upper part has polyps all around the branches. The calyces are dome-shaped, and most polyps are expanded. Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig. 82a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 82b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 82c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 82d). Coenenchyme with predominantly capstans (Fig. 82f), double disks (Fig. 82g), and unilaterally foliate spheroids (Fig. 83b), 0.05–0.15 mm long, and small clubs (Fig. 82h), up to 0.10 mm long. Spindles are also present, 0.10-0.25 mm long, with simple or complex tubercles (Fig. 83c). The calyces with additional clubs, up to 0.15 mm long (Fig. 83a). The axis has smooth and sparsely tuberculate rods (Fig. 82e).

Figure 82.

Sclerites of Melithaea satsumaensis sp. n., RMNH Coel. 41936; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod f capstans g double disks h clubs of coenenchyme.

Figure 83.

Sclerites of Melithaea satsumaensis sp. n., RMNH Coel. 41936; a clubs of calyx b unilaterally foliate spheroids c spindles.

Color

Colony orange with yellow polyps, coenenchymal sclerites orange, polyp ones yellow.

Distribution

Off Cape Sata misaki, Kagoshima Prefecture (Fig. 86).

Etymology

The species is named after the type locality, Satsuma, the old name of Kagoshima Prefecture.

Remarks

This species is unique by its unilaterally foliate spheroids and spindles with complex tubercles.

Melithaea suensoni sp. n.

Figures 75d, 84, 85, 86

Material examined

Holotype ZMUC ANT-000565, off Nagasaki, 32°22'N, 128°42'E, 170 fms (311 m), 25 December 1900, coll. Suenson.

Description

Colony branched in one plane, with slender branches (Fig. 75d). Points with slightly bent spindles up to 0.30 mm long, distal end with more developed tubercles or leaves (Fig. 84a). Collaret with bent spindles up to 0.35 mm long, middle part with more developed tubercles (Fig. 84b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 84c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 84d). Coenenchyme with capstans (Fig. 84e) and disk spindles (Figs 84f, 85c), 0.05–0.15 mm long, and small clubs of similar length (Fig. 84g). Spindles are also present, 0.15–0.30 mm long, with simple or complex tubercles (Fig. 85b). The calyces with additional clubs, up to 0.20 mm long (Fig. 85a).

Figure 84.

Sclerites of Melithaea suensoni sp. n., ZMUC ANT-000565; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e capstans f disk spindles g clubs of coenenchyme.

Figure 85.

Sclerites of Melithaea suensoni sp. n., ZMUC ANT-000565; a clubs of calyx b spindles c disk spindles.

Color

White with orange calyces and polyps. Sclerites of calyces and polyps faint pink, all others colorless.

Distribution

Off Nagasaki, East China Sea (Fig. 86).

Figure 86.

Distribution of Melithaea sagamiensis sp. n. (*), BMNH 62.7.16.62(61?) (♦), M. satsumaensis sp. n. (●), and M. suensoni sp. n. (■).

Etymology

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 (Matsumoto 2014, 2015).

Remarks

This species resembles M. sagamiensis sp. n., but differs by its thicker coenenchymal spindles.

Melithaea tanseii sp. n.

Figures 87a, 88, 89, 98

Material examined

Holotype RMNH Coel. 41937 (AKM 948), Toshima Is., Izu Isls., 34°33.1102'N, 139°17.4102'E34°33.6524'N, 143 m, R/V Tansei-maru, KT07-31 (Kuramochi leg.) St. 22 (L-3-100), coll. A.K. Matsumoto; paratype: RMNH Coel. 41938 (AKM 941) Toshima Is., Izu Isl, 34°34.4640'N, 139°18.3760'E34°33.5601'N, 139°17.8631'E, 152–198 m, R/V Tansei-maru, KT07-31 (Kuramochi leg.) St. 21 (L-3-200), coll. A.K. Matsumoto.

Description

The holotype (RMNH Coel. 41937) consists of a large number of branches probably belonging to one colony broken up while collecting (Fig. 87a). The largest fragment, with the holdfast, is 6.5 cm long. The stem is 10 mm long and 3 mm wide; branching is in one plane. A few anastomoses are present. The polyps are situated on one side of the colony. The calyces are dome-shaped, about 0.5 mm high and 1 mm wide. Many polyps are expanded. Points with slightly bent spindles up to 0.20 mm long, distal end with more developed tubercles (Fig. 88a). Collaret with bent spindles up to 0.25 mm long, middle part with more developed tubercles (Fig. 88b). Tentacles with platelets, the larger ones crescent-shaped (Fig. 88c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 88d). Coenenchyme with capstans (Fig. 89a) 0.05–0.07 mm long, several slightly unilaterally foliate (Fig. 89b), unilaterally foliate spindles (Fig. 89c), small clubs of the same length as the capstans (Fig. 88e); spindles 0.10–0.25 mm long (Fig. 89d); all with simple tubercles. The calyces with additional clubs, up to 0.20 mm long (Fig. 88f).

Figure 87.

a Melithaea tanseii sp. n., holotype RMNH Coel. 41937 b M. tenuis syntype ZMB 5799 c M. tokaraensis sp. n. RMNH Coel. 41941 d M. undulata holotype ZMB 5803 e RMNH Coel. 42030.

Figure 88.

Sclerites of Melithaea tanseii sp. n., RMNH Coel. 41937; a point spindle b collaret spindles c tentacle sclerites d pharynx rods e clubs of coenenchyme f clubs of calyx.

Figure 89.

Sclerites of Melithaea tanseii sp. n., RMNH Coel. 41937; a capstans b unilaterally foliate capstans c unilaterally foliate spindles d spindles.

Color

Colony white with the larger yellowish nodes shining through the coenenchyme. All sclerites colorless.

Distribution

Izu Isls (Fig. 98).

Etymology. The species is named after the R/V Tansei-maru.

Remarks

The paratype (RMNH Coel. 41938) is just a fragment of colony, only three cm long with characters alike those of the holotype. The species mostly resembles M. tenuis but differs in having much wider coenenchymal spindles, up to 0.07 mm wide, twice as wide as in M. tenuis, in which they are only 0.03 mm wide. A few spindles in M. tenuis are wider, mainly caused by the spindles having bigger tubercles. Another difference is the slightly bigger capstans in the new species, but this is only noticeable when having both species.

Melithaea tenuis (Kükenthal, 1908)

Figures 87b, 90, 91, 98

Acabaria tenuis: Kükenthal 1908: 195; Kükenthal 1909: 61, figs 64–67, pl. 5 fig. 27 (Sagami Bay, Okinose Bank); Kükenthal 1919: 183; Kükenthal 1924: 78; Aurivillius 1931: 24 (Sagami Bay, 400 fms); Hickson 1937: 177.

Acabaria sp. aff. tenuis: Aurivillius 1931: 25, fig. 3 (Sagami Bay, 200 m).

Not Acabaria tenuis: Nutting 1911: 45 (Indonesia).

? Acabaria tenuis: Rho et al. 1980: 53 (Korea Strait).

Material examined

Syntype ZMB 5799, Sagami Bay (Japan), 600 m (label 60-250 m), coll. Doflein,1904/05; previously unidentified museum material: BMNH 1921.10.26.9-2, Misaki, Sagami Bay, 200 fms (286–366 m), coll. A.V. Insole, May 1921; BMNH 1921.10.26.7, same data as BMNH1921.10.26.9-2; ZMUC ANT-000593, Sagami Bay, 400 fms, coll. Dr. Th. Mortensen, 2 July 1914; ZMUC ANT-000594, Sagami Bay, Japan, 80–120 fms (114–219 m), coll. Dr. Th. Mortensen, 6–19 June 1914; ZMUC ANT-000661, Sagami Sea, 300 fms (429–549 m), coll. Dr. Th. Mortensen, 29 June 1914; ZMUC ANT-000656, off Misaki Biological Station, Sagami Bay, 200 fms (286–366 m), coll. Dr. Th. Mortensen, 30 June 1914; ZMUC ANT-000651, Off Misaki, Sagami Bay, ca. 250 fms (ca.358–457 m), coll. Dr. Th. Mortensen, 10 June 1914; UMUTZ-CnidG-16, near Doketsuba, Sagami Bay, 170-180 hiro (243–272 m), coll. Kuma Aoki, 12 August 1895; UMUTZ-CnidG-198, Mera-no-hai-dashi-Oise line, Sagami Bay, 350 fms (500–529 m), coll. H. Matsumoto and H. Chiba, 21 July 1913; UMUTZ-CnidG-233, Gokeba, Sagami Bay, 150-20 hiro (227–29 m), coll. Kuma Aoki, 18 June 1902; AKM 142, East China Sea, R/V Tanisei-maru, KT02-03, st.E-5-1, 1 m Dredge, 19 April 2002; AKM 234, South of Mera-se Bank, Sagami-bay, 34°60.0'N, 139°40.2'E35°0.0'N, 139°40.3'E, 97–108 m, 17 October 2003; AKM 235, same data as AKM 234; AKM 413, Watari-se bank, Off Izu Isls., 34°02.8620'N, 138°54.8090'E34°02.9190'N, 138°54.6810'E, 101.1-106.2 m, R/V Tansei-maru, KT04-06, st. WS-2, 1 m ORI dredge, coll. A.K. Matsumoto, 30 April 2004; RMNH Coel. 41939 (AKM 414), same data; AKM 415, same data; AKM 421, same data; AKM 422, same data; RMNH Coel. 41940 (AKM 521), Otsuki, Tosa, Kochi prefecture, 132°50.44'E 32°37.66'N, – 132°47.88'E 32°37.56'N, 114 m, local fishermen’s boat Kiryo-maru, St. 1, coral net, coll. A.K. Matsumoto, 7 October 2004; AKM 663, off Tanabe, Wakayama Prefecture, 33°39.05'N, 135°09.89'E33°38.96'N, 135°10.16'E, 170.3-173.1 m, R/V Tansei-maru, KT05-30, st. TN-1 (1), coll. A.K. Matsumoto 26 November 2005; RMNH Coel. 41942 (AKM 664),same data as AKM663; AKM 670, off Tanabe, Wakayama Prefecture, 33°39.02'N, 135°09.89'E33°39.03'N, 135°09.07'E, 169.8-172.5 m, R/V Tansei-maru, KT05-30, TN-1 (2), coll. A.K. Matsumoto, 26 November 2005; AKM 745, off Satamisaki Cape, Kagoshima Prefecture, 30°56.0025'N, 130°44.2299'E30°56.2953'N, 130°43.3981'E, 116-120 m, R/V Tansei-maru, KT07-1, st.SM-1, Chain Bag Dredge, coll. A.K. Matsumoto, 23 February 2007; RMNH Coel. 41943 (AKM 980), Tsukura-se bank, Kagoshima Prefecture, East China Sea, 31°18.95'N, 129°46.15'E31°18.50'N, 129°45.96'E, 154–155 m, R/V Tansei-maru, KT08-3, St. NM05, ORI-TI Chain Bag Dredge, coll. A.K. Matsumoto, 6 March 2008; AKM 983, same data as RMNH Coel. 41943; AKM 1222, off Takarajima Is., Tokara Isls, East-China Sea, 29°05.29'N, 129°10.43'E, 334 m, R/V Tansei-maru, KT07-21, st. DT0203-1, Chain Bag Dredge, coll. Yokose, 31 August 2007; AKM 1230, same data as AKM1222; AKM 1598, Otsuki, Tosa, Kochi Prefecture, 32°37'N, 132°50'E, 114 m, local fishermen’s boat Kiryo-maru, st. 1, coll. A.K. Matsumoto, 7 October 2004; AKM 1600, Otsuki, Tosa, Kochi Prefecture, 32°43.08'N, 132°48.06'E32°43.12'N, 132°47.68'E, 84.75-83.1 m, local fishermen’s boat Kiryo-maru, st. 3, coll. A.K. Matsumoto, 7 October 2004.

Re-description

Colony branched in one plane, with slender branches (Fig. 87b). Points with slightly bent spindles up to 0.15 mm long, distal end with more developed tubercles (Fig. 90a). Collaret with bent spindles up to 0.20 mm long, middle part with more developed tubercles (Fig. 90b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 90c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 90d). Coenenchyme with capstans (Fig. 91c), about 0.05 mm long, small clubs of the same length (Fig. 91a); unilaterally spinose spheroids and unilaterally spinose spindles up to 0.10 mm long (Fig. 91d); spindles are also present, 0.10–0.18 mm long (Fig. 91e). The calyces with additional clubs, up to 0.15 mm long (Figs 90e, 91b).

Figure 90.

Sclerites of Melithaea tenuis, ZMB 5799; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e clubs of calyx.

Figure 91.

Sclerites of Melithaea tenuis, ZMB 5799; a clubs of coenenchyme b clubs of calyx c capstans d unilaterally foliate spheroids and spindles e spindles.

Color

Colony red with white/yellow polyps, polyp sclerites colorless or yellow, all others orange.

Variation

Colonies can be yellow with all sclerites yellow or white with all sclerites colorless.

Distribution

Sagami Bay, and now South to East China Sea (Fig. 98).

Remarks

We did not examine ZMB 5805, syntype, Okinose Bank (Japan), 80–250 m, coll. Doflein 1904/05 because the material consists of only small fragments.

Melithaea tokaraensis sp. n.

Figures 87c, 92, 93, 98

Material examined

Holotype RMNH Coel. 41941 (AKM 1212), 28°54.90'N, 129°04.09'E, off Yokoate-jima, Tokara Islands, East China Sea, 395 m, R/V Tansei-maru, KT07-21, St. DY0205, Chain Bag Dredge, coll. Dr. H. Yokose, 30 August 2007.

Description

Colony branched in one plane, broken up while collecting (Fig. 87c). The largest fragment being 12 cm long. The larger nodes are swollen and clearly visible. The polyps are situated on one side of the colony. The calyces are dome-shaped, about 0.5 mm high and 1 mm wide. Points with slightly bent spindles up to 0.25 mm long, distal end more tuberculate (Fig. 92a). Collaret with bent spindles up to 0.35 mm long, middle part with more developed tubercles (Fig. 92b). Tentacles with platelets, the larger ones crescent-shaped with irregular projections (Fig. 92c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 92d). Coenenchyme with predominantly capstans, double disks (Fig. 93b) and disk spindles (Fig. 93c), 0.05–0.15 mm long, and small clubs (Fig. 92f), up to 0.10 mm long. Spindles are also present, 0.10–0.30 mm long, mostly with simple tubercles (Fig. 93d). The calyces with additional clubs, up to 0.25 mm long (Fig. 93a). The axis has smooth and sparsely tuberculate rods (Fig. 92e).

Figure 92.

Sclerites of Melithaea tokaraensis sp. n., RMNH Coel. 41941; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e axial rod f clubs of coenenchyme.

Figure 93.

Sclerites of Melithaea tokaraensis sp. n., RMNH Coel. 41941; a clubs of calyx b double disk c disk spindles d spindles.

Color

Colony red, all sclerites orange.

Distribution

Only known from off the Tokara Islands. (Fig. 98).

Etymology. The species is named after the type locality, the Tokara Islands.

Remarks

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.

Melithaea undulata (Kükenthal, 1908)

Figures 87d–e, 94, 95, 96, 97, 98

Acabaria undulata Kükenthal 1908: 196; 1909: 63, figs 68–69, pl. 5 fig. 28, pl. 7 figs 40–43 (Japan); 1919: 179; 1924: 76; Hickson 1937: 181.

? Acabaria undulata; Rho et al. 1980: 54 (Korea Strait); Song 2000: 121 (Korea Strait).

Material examined

Holotype ZMB 5803, Sagami Bay, Japan, 700 m, coll. Doflein, 1904/05; previously unidentified museum material: ZMUC ANT-000592, Sagami Sea, Japan, 500 fms (715-914 m), coll. Dr. Th. Mortensen, 25 June 1914; BMNH 1921.10.26.9-1, BMNH 1921.10.26.9-2, Misaki, Sagami Bay, 200 fms (286-366 m), coll. A.V. Insole, May 1921; MZS-Cni57, Sagami Bay, 200 m, coll. Doederlein. UMUTZ-CnidG-14, Niijima Is., Izu Isls., coll. sp. no. 80, 22 April; UMUTZ-CnidG-20, Dokesuba, Sagami Bay, 130 hiro (186–196 m), coll. Kuma Aoki, 9 August 1897; UMUTZ-CnidG-234, Mochiyama, Sagami Bay, 400 hiro (572–604 m), possibly coll. Kuma Aoki; AKM 502, Ose-zaki, Suruga Bay, 137–155 m, coll. K. Kitazawa, 22 July, 2004; RMNH Coel. 42030 (AKM 724), off Tanega-shima Is., East China Sea, 30°24.62'N, 131°08.46'E30°24.95'N, 131°08.32'E, 468-502 m, R/V Tansei-maru, KT07-1, st. TN-3, 1 m biological dredge, coll. A.K. Matsumoto, 23 February 2007; AKM 1034, Koshiki Knoll, off Kagoshima, East China Sea, 31°36'N, 129°19'E, 497-535 m, R/V Tansei-maru, KT08-3, st. KS-01, coll. A.K. Matsumoto, 6 March, 2008; AKM 1591, Danzyo-Basin, East China Sea, 31°58.02'N, 129°02.28'E31°59.30'N, 129°01.19'E, 711-801 m, R/V Tansei-maru, KT00-17, St. DZ-1, ORE Beam Trawl of 3 m span, coll. Suguru Ohta, 12 December 2000; AKM 1592, same data as AKM1591; AKM 1593, South East off Taito-saki Cape, Boso Peninsula, 35°05.086'N, 140°51.718'E35°04.176'N, 140°50.92'E, 975-1027 m, R/V Tansei-maru, KT03-17, st. TS6-3, coll. S. Ohta, 17 November 2003; AKM 1599, South off Daio-zaki Cape, Kumano-nada, 34°05'N, 136°51'E, R/V Tanisei-maru, KT94-07, st. KN25, 25 May 1994, 475-494 m, coll. S. Ohta; AKM 1604, west off Izu-Oshima, Sagami Bay, 139°15.0'E 34°40.4'N, 415-440 m, R/V Hakuho-maru, KH-78-05, st. BS8, 2 m S.-A. beam trawl (on label), 7 December 1978.

Re-description

Colony branched in two parallel planes. Points with slightly bent spindles up to 0.25 mm long, distal end with more developed tubercles (Fig. 94a). Collaret with bent spindles up to 0.30 mm long, middle part with more developed tubercles (Fig. 94b). Tentacles with platelets, the larger ones crescent-shaped (Fig. 94c). These platelets are up to 0.15 mm long. Pharynx with straight spiny rods, up to 0.05 mm long (Fig. 94d). Coenenchyme with capstans (Fig. 95b) about 0.05 mm long, several slightly unilaterally spinose, small clubs of the same length (Fig. 95a); spindles 0.10–0.30 mm long (Fig. 95c); all with simple tubercles. The calyces with additional clubs, up to 0.12 mm long (hardly present in type material). The axis has smooth and sparsely tuberculate rods (Fig. 94e).

Figure 94.

Sclerites of Melithaea undulata, ZMB 5803; a point spindles b collaret spindles c tentacle sclerites d pharynx rods e axial rod.

Figure 95.

Coenenchymal sclerites of Melithaea undulata,ZMB 5803; a clubs b capstans c spindles.

Color

Colony red, tentacle sclerites colorless, all others pink.

Variation

AKM 502 is yellow with yellow sclerites.

Distribution

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. 98).

Remarks

The type specimen clearly has damaged sclerites, probably caused by formalin. Recently collected material shows less rounded sclerites (Figs 87e, 96, 97). Double disks are present but so poorly developed that they can hardly be recognized as such.

Figure 96.

Sclerites of Melithaea undulata, RMNH Coel. 42030; a point spindles b collaret spindles c tentacle sclerites d pharynx rod e axial rod f clubs of coenenchyme g capstans of coenenchyme.

Figure 97.

Sclerites of Melithaea undulata, RMNH Coel. 42030; a clubs of calyx b unilaterally spinose spindles c spindles.

Figure 98.

Distribution of Melithaea tanseii sp. n. (*), M. tenuis (●), M. tokaraensis sp. n. (■), and M. undulata (□).

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. 87d) of a colony described as being 21 cm long (Kükenthal 1909).

Unidentified material (disintegrated sclerites)

BMNH1921.10.26.24-1, Misaki, Sagami Bay, 500–600 fms, coll. A.V. Insole, No. 45; ZMUC ANT-000648, Sagami Bay, Okinose, 60 fms (86–110 m), 11 June 1914, coll. Dr. Th. Mortensen, hard bottom, Gear: swabs; ZMUC ANT-000589, Okinose, Sagami Sea, 60 fms (86–110 m), 11 June 1914, coll. Dr. Th. Mortensen; ZMUC ANT-000652, 34°20'N, 130°10'E, 60 fms (86–110 m), 18 May 1914, coll. Dr. Th. Mortensen; UMUTZ-CnidG-13, Doketsuba, Sagami Bay, Japan, 60 fms (86–91 m), coll. K. Kinoshita, October 1908; UMUTZ-CnidG-18, Kashiwajima Is., Tosa, Kochi Prefecture, Japan, coll. K. Kinoshita, June 1909; UMUTZ-CnidG-26, Shikine Is., Izu Isls., Japan; UMUTZ-CnidG-39, Kashiwajima Is., Tosa, Kochi Prefecture, Japan, June 1909 (possibly collected by K. Kinoshita as same as UMUTZ-CnidG-18); UMUTZ-CnidG-40, Cape Matsu-zaki, east of Izu Peninsula, Sagami Bay, coll. M. Miyajima, 29 August 1897; UMUTZ-CnidG-270 (G-40b), same data as UMUTZ-CnidG-40; UMUTZ-CnidG-191, same data as UMUTZ-CnidG-18; UMUTZ-CnidG-206, Ogasawara Isls., coll. S. Hirota and Sekiguchi, 11 April 1894.

Discussion

We compared Japanese melithaeids with those described from other parts of the Indo-Pacific (Hickson 1937, Ofwegen 1987, Ofwegen et al. 2000, Reijnen et al. 2014) and never found a match based on examination of sclerites. Therefore we conclude they are all endemic to Japan.

The only Japanese melithaeid species described by Kükenthal (1908) which we could not check was M. habereri. The material of that species seems to be lost. As well we could not find the two varieties described by Kükenthal M. flabellifera var. reticulata Kükenthal, 1908, and M. flabellifera var. cylindrata Kükenthal, 1908. The type material of Pleurocorallium confusum Moroff, 1902, was not found but from the original description, i.e. colony with flattened branches, it was obvious this species could be synonymized with M. japonica. The material used to describe M. mutsu Minobe, 1929 has also been lost but for this species we designated a neotype (Figs 56c, 6365).

Most of the already described melithaeid species could be identified again from newly collected material. However, specimens of Melithaea arborea Kükenthal, 1908 (Figs 8, 9a, 10, 11), M. frondosa (Brundin, 1896) (Figs 28b, 31, 32, 35), and M. nodosa Wright and Studer, 1889 (Figs 66abc, 6769, 74) could not be retrieved. We do not exclude the possibility that M. arborea is nothing else than M. japonica but somehow with its clubs lost. It is puzzling why we could not find M. frondosa and M. nodosa, as we did examine material from the regions from which these species were described, Hirado Strait (Fig. 35) and Sagami Bay (Fig. 74), respectively.

We have tentatively included BMNH 1921.10.26.24-2 in Melithaea abyssicola. It had sclerite damage caused by formalin (Figs 6, 7).

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: RMNH Coel. 41903(Figs 14c, 21, 22); RMNH Coel. 41908 (Figs 14d, 23, 24) and RMNH Coel. 41909; RMNH Coel. 41910 and RMNH Coel. 41911 (Figs 14e, 25, 26); and ZMUC ANT-000646. They all were collected from South Japan (Fig. 27).

We included BMNH 62.7.16.62(61?) in Melithaea sagamiensis sp. n. despite its slightly different sclerites (Figs 80, 81). It was collected in quite shallow water, 25 feet (= 7.62 m) -30 feet (= 9.14 m) from off Okushiri, Sea of Japan (Fig. 86). This specimen is the northernmost melithaeid coral ever found.

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 Matsumoto 2004).

Reijnen et al. (2014) used eight Japanese specimens in their molecular study. At that time only RMNH Coel. 41942 was identified, as M. tenuis. Here the other seven specimens are also identified, or described as new species, and their affinities are examined. M. keramaensis sp. n. appears to be genetically identical to specimens from Indonesia, Vietnam, and Malaysia (Reijnen et al. 2014: Fig. 2). Of these it morphologically mostly resembles RMNH.Coel.41142 from Malaysia but clearly differs from that species in having disk spindles. M. satsumaensis sp. n. is the only other species genetically somewhat different from the other Japanese specimens, which is supported by its sclerites looking like those belonging to the now abandoned genus Mopsella, while the other Japanese specimens in the tree could be abandoned genus Acabaria or valid genus Melithaea. The remaining six specimens did not differ genetically from each other while we identified them as three different species, M. corymbosa, M. japonica, and M. tenuis. This result could be explained by imagining deep water M. corymbosa and M. tenuis show different sclerites and colony shape from shallow water M. japonica, and the differences noted are merely reflecting ecophenotypic variation instead of interspecific variation. Ofwegen (1987: 20) and Ofwegen et al. (2000: 291) already reported species including specimens with different sclerites. The main sclerite difference between M. corymbosa and M. tenuis is in the presence of capstans and derivatives of those, many present in M. tenuis and only few in M. corymbosa. We can imagine this also reflecting variability and these two species actually being one and the same. If this is the case M. japonica, M. tenuis and M. corymbosa all could represent one and the same species. However, many specimens of these three species are not included in the molecular study and these complicate the above possibility of variability. The M. corymbosa specimen used in not typical of that species (see Remarks M. corymbosa), most specimens come from Sagami Bay and have slightly different sclerites. The M. japonica specimens used for the molecular work all came from the Pacific of northern Japan, with the deepest occurrence, while this species is most common in Sagami Bay, with slightly different sclerites than the northern specimens (see Remarks M. japonica). With two species of the three used in the molecular study presented by rather atypical specimens we decide to keep all three species separate till more study has been done.

Sagami Bay and adjacent waters produced four new species: M. doederleini sp. n. (60–100 fms (108–183 m); Figs 28a, 29, 30, 35), M. sagamiensis sp. n. (286–440 m; Figs 75a, 75b, 7681, 86), M. oyeni sp. n. (101.1–127 m; Figs 66d, 70, 71, 74) and M. tanseii sp. n. (143–198 m; Figs 87a, 88, 89, 98) bringing the total number of Melithaea species from Sagami Bay to 13, making it the richest melithaeid region of Japan. All four were collected from deep water (101.1–440 m). The depth between 100–200 m is known as having the highest octocoral species diversity in Japan and adjacent waters (Matsumoto et al. 2007). In total five new species are here described from this depth region.

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. 86); four species (M. japonica, M. corymbosa, M. mutsu, M. sagamiensis sp. n.) are distributed in the northern region of Japan with maximum depth ca.100 m; three specimens of M. japonica from the northern region have extreme slender sclerites but are still identified as M. japonica (Figs 5355); M. mutsu collected from the area between the Sea of Japan and the Pacific at 5 m depth (Fig. 65). No deep water Melithaeidae species were found in the Sea of Japan.

Other new species were collected from the Ogasawara Isls. (= Bonin Islands) (M. boninensis sp. n.; Fig. 8)).The Bonin Islands are isolated from main Japan by currents such as warm Kuroshio Current. We also described five new species from the East China Sea: M. isonoi sp. n. (found on coral reef; Fig. 35), M. keramaensis sp. n. (51–85 m; Fig. 65), M. ryukyuensis sp. n. (shallow diving depth; Fig. 74), M. suensoni sp. n. (311 m; Fig. 86) and M. tokaraensis sp. n. (395 m; Fig. 98), and one new species from Osumi Peninsula of southernmost Kyushu Is.: M. satsumaensis sp. n. (116–120 m; Fig. 86).

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. 86) located between the Pacific Ocean and the East China Sea.

Nutting (1912) reported Mopsella dichotoma (Linnaeus, 1758) from Cape Tsiuka (unknown Japanese locality name; 41°35.50'N, 140°36.45'E, Tsugaru Strait between the Sea of Japan and the Pacific Ocean), but this is likely to be a misidentification because the type locality of M. dichotoma is South Africa. A previous study did not report the existence of melithaeid corals in the Sea of Japan (Dautova 2007). Song (2000) and Rho et al. (1980) reported melithaeid corals previously described from Japan in Korean waters, the Sea of Japan and the East China Sea. We regard them as doubtful identifications as their descriptions lack detail for comparison.

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 (Oba et al. 1991, Ishiwatari et al. 2001, Yokoyama et al. 2000). It was a geographical barrier for the distribution of the marine organisms with a planktonic larvae stage, such as corals. Considering the highest species diversity depth range at Sagami Bay (100–200 m) the age of the Sea of Japan and the LGM barrier between 0–130 m could have restricted the warm Indo-Pacific species from the South to enter the Sea of Japan.

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.

Acknowledgements

The following persons are thanked for hospitality during visits: Dr. Bernhard Ruthensteiner, Section Evertebrata varia, ZSM, Munich, Germany; Dr. Helmut Sattmann and Mr. Stefan Szeiler, NHMW, Wien, Austria; Ms. Erica Sjölin and Mr. Hans Mejlon, ME, Uppsala, Sweden; Madame Marie-Dominique Wandhammer, and Marie Meister, MZS, Strasbourg, France; Ms. Miranda Lowe and Mr. Andrew Cabrinovic, BMNH, London, UK; Dr. Mathew Lowe, UMZC, Cambridge, UK; Dr. Rei Ueshima, UMUT, Tokyo, Japan; Dr. Carsten Lueter, ZMB, Germany; Dr. Ole Tendal, Ms. Majken Toettrup and Dr. Martin V. Sørensen, ZMUC, Copenhagen, Denmark; Prof. Dr. Hilke Ruhberg, Dr. Peter Stiewe, and Dr. Andreas Schmidt-Rhaesa, ZMH, Hamburg, Germany; Dr. Shigeyuki Yamato, SMBL, Kyoto, Japan, and Dr. Masahiro Nakaoka, Akkeshi Marine Station, Field Science Center for Northern Biosphere Hokkaido University, Japan. Ms. Eva Lodde-Bensch, ZSM, is acknowledged for loan of fragments of Pleurocoralloides formosum and Acabaria modesta var. abyssicola. Dr. Suguru Ohta, University of Tokyo and Dr. Hisayoshi Yokose, University of Kumamoto are thanked for collecting material. The local fishermen of the boats Kiryo-maru and Taku-maru, and the captain and crew of R/V Tansei-maru and R/V Hakuho-maru, University of Tokyo and Japan Agency for Marine-earth Science and Technology, and R/V Yayoi, University of Tokyo, and R/V Shinyo-maru, Tokyo University of Marine Science and Technology, are also thanked for collecting. We are grateful to the International Coastal Research Center in Otsuchi for the use of the facilities. The SEM facility and financial support of the Planetary Exploration Research Center (PERC), Chiba Institute of Technology is thanked. The research was partially financially supported by Cooperation Research from the Ocean Research Institute, University of Tokyo (H10-109, H13-110, H14-132, H16-131, H17-131, H18-110, H20-001, H21-001) and by the Higashi Nippon International University. We thank Bastian T. Reijnen for sharing his molecular data with us and Dr. Catherine S. McFadden and two anonymous reviewers for comments on the manuscript.

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