Japanese Journal of Ichthyology 魚 類 学 雑 誌 Vol.35, No.1 1988 35巻1号 1988年

Notes on Halosauropsis macrochir (Halosauridae: ) from Japan

Yoshihiko Machida, Osamu Okamura and Suguru Ohta

(Received June 20, 1987)

The monotypic deep-sea genus Halosaurop sis is well characterized by a deeply pigmented sheath on the lateral line, the absence of scales from the top of its head, the presence of scales on the opercular bone, the long and segmented first dorsal ray, and the long unpigmented pyloric caeca

(McDowell, 1973). A comprehensive study of the Atlantic and South African specimens was made by McDowell (1973). Paulin and Moreland

(1979) first reported H. macrochir from the Pacific, based on material from the Bay of Plenty, New Fig. 1. Distribution of Halosauropsis macrochir Zealand. A recent study by Filatova (1985) re around Japan. vealed that this species is widely distributed in the

Indian. Ocean. The first report of H. macrochir Feb. 1969; BSKU 43473, 1 specimen, female, 227mm from Japanese waters was based on underwater GPL, 32•‹03.9'N, 132•‹17.7'E-32•‹08.9'N, 132•‹18.7'E, photographs and trawled specimens collected Hyuga Basin off Cape Ashizuri, southern Japan, 1,514 during ecological surveys in Suruga Bay and 1,463m, trawled by the R.V. Tansei Maru, 3 - Nov.

Sagami Bay (Ohta, 1983). No taxonomic descrip 1986; ORIUT•EKT•E8213•E013300-KT•E8213•E013302, 3

tion of the specimens was given. specimens, 1male and 2 females, 230-272mm GPL,

In this paper we report specimens of H. macro 34•‹52.7'N, 139•‹27.5'E-34•‹52.8'N, 139•‹29.0'E, Sagami

chir collected from central and southern Japan Bay, central Japan, 1,505-1,665m, trawled by the R.V. Tansei Maru, 7 Dec. 1982; ORIUT•EKT•E8601•E (Fig. 1) and present a new Japanese name, kuro 03.3303-KT•E8601•E03•E3307, 5 specimens, 4males and obi-tokagegisu, in reference to the black, sheath- 1 female, 165-240mm GPL, 34•‹30.1'N, 138•‹34.0'E on the lateral line. We discuss meristic char 34•‹29.3'N, 138•‹34.2'E, Suruga Bay, central- Japan, acteristics of our specimens in relation to the - dis 2,716-2,743m, trawled by the R.V. Tansei Maru, tribution of this species, as well as underwater - 26 Feb. 1986; ORIUT•EKT•E8606•E063308-KT•E8606•E photographic observations. Our material is de 063309, 2 specimens, male and female, 229-250mm

posited in the Department of Biology, Faculty - of GPL, 33•‹46.6'N, 136•‹40.0'E-33•‹46.6'N, 136•‹37.6'E, Science, Kochi University (BSKU) and the Ocean Kumano Basin, southern Japan, 2,026-2,045m, trawl

Research Institute, University of Tokyo (ORIUT). ed by the R.V. Tansei Maru, 27 May 1986; ORIUT•E- KT•E8616•E153310, 1 specimen, female, 199mm GPL,

32•‹21.3'N, 132•‹27.9'E-32•‹23.2'N, 132•‹28.7'E, Hyuga Halosauropsis macrochir (Gunther, 1878) Basin, 1,642-1,651m, trawled by the R.V. Tansei

Maru, 2 Nov. 1986. (New Japanese name: Kuroobi-tokagegisu) (Fig. 2) Description. Counts and proportional measure ments are given in Table 1. Material examined. Thirteen specimens, 165-272 Head depressed anteriorly, tail strongly com mm in GPL (=gnathoproctal length, the distance from the anteriormost tip of the mandible to the middle pressed posteriorly. Preoperculum posteriorly -

of the vent). BSKU 19675, 1 specimen, male, 225mm elongate, scarcely reaching to below the base of

GPL, 32•‹24.7'N, 140•‹03.6'E, north of Torishima, central pectoral fin. Posteriormost branchiostegal ray Japan, 1,490m, trawled by the R.V. Soyo Maru, 10 broad and expanded. First dorsal ray segmented

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Fig. 2. Lateral aspect of Halosauropsis macrochir, BSKU 43473, female, 227mm GPL. (Photographed by Okamura.)

Table 1. Comparison of meristic counts and proportional dimensions of Halosauropsis macrochir from different areas. *% of preanal.

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Fig. 3. Underwater photograph of Halosauropsis macrochir on the ocean bottom of Kumano Basin at a depth of 2,050m. (Photographed by Ohta.) and as long as 2nd dorsal ray. Body and tail stegal rays. These differences, though slight, completely covered with cycloid scales. Scales suggest there are slight differences between our absent from top of head, lateral side of head material and the four specimens reported by them . before posterior margin of dermal cornea, un Some meristic characters of 83 Indian Ocean derside of head, and branchiostegal membranes.- specimens of H. macrochir displayed considerably Opercular bone scaly. One lateral line scale for large variation (Filatova, 1985): specimens from every two vertical scale rows. Pyloric caeca long, Madagascar and the southeast Indian Ocean arranged in a single row at the base. have ten dorsal rays; specimens from the "Zvezda Overall coloration as in Fig. 2. Lateral line Kryma" Bank (eastern Indian Ocean off Western sheath black. Mouth cavity bluish gray except Australia) and the Great Australian Bight have for blackish palatine tooth bands. Peritoneum 14 pectoral rays; and specimens from the "Zvezda brownish. Pyloric caeca creamy white. Kryma" Bank and the southern part of the eastern Remarks. Table 1 shows intraspecific vari Indian Ocean (west of "Zvezda Kryma" Bank) ations in the meristic counts and proportional- have eight pelvic rays. dimensions of Halosauropsis macrochir from dif H. macrochir is not uncommon, as evidenced ferent areas in the world. Our material differs- by the catch frequency in our study (13 specimens slightly from the Atlantic specimens described by in six trawls). The species inhabits the lower McDowell (1973) in the counts of the pyloric caeca bathyal zone between 1,490 and 2,740m in Japan . (9-11, mode 9 vs. 10-12, usually 12). It also dif The global bathymetric range for this species is fers from the Atlantic specimens from off -the 1,080 to 3,105m (Filatova, 1985). Using under Sahara (Golovan, 1976) in the counts of lateral water photographic census, Ohta (1983) estimated- line scales from the head to vent (25-26 vs. 27-29, the population density of H. macrochir in Suruga mode 28). Paulin and Moreland (1979) found Bay to be about 2.5 individuals/1,000m2 between that four specimens from the southwest Pacific the depths of 2,035 and 2,055m. For the western and the Great Australian Bight have 11 to 12 North Atlantic population of this species, there pyloric caeca and 11 to 12 branchiostegal rays. are some quantitative studies. Grassle et al . However, of our 13 specimens, only one has 11 (1975) estimated the population density on the pyloric caeca and none has less than 12 branchio- continental slope at depths ranging from 1,798 to

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1,830m to be 1.10 individuals/1,000m2 on the sle et al., 1975), we conclude that H. macrochir basis of photographic census using the deep re lives close to the bottom, gulping down infaunal search submersible Alvin. According to Cohen and epifaunal organisms, detritus and sediments. and Pawson (1977), H. macrochir was the fourth most common species of benthic which Acknowledgments were seen from the Alvin in "Deepwater Dumpsite 106" at depths ranging from 1,704 to 2,808m, and We are grateful to an anonymous reviewer for its greatest abundance based on visual census was revision and critical reading of our manuscript. 2.37 individuals/1,000m2 at a depth range of We thank Dr. Takashi Okutani of Tokyo Uni 1,768-1,960m. In the Norfolk Canyon area, its versity of Fisheries who donated a specimen trawl abundance expressed as individuals per 1,000m2 ed by the R.V. Soyo Maru. Our thanks also go ranged from 0.03 to 0.35 with the greatest abun to Dr. Seiji Goshima of Hokkaido University dance at a depth range of 1,500-1,999m (Wenner, for his help in obtaining literature, and to Ms. 1978). Though the estimated density of H. Patricia J. Kailola of the University of Adelaide macrochir based on benthic trawls by Wenner is for correcting the English. lower than others, the population density and main bathymetric range of this species in Suruga Literature cited Bay agree well with those in the western North Atlantic. Cohen, D.M. and D.L. Pawson. 1977. Observa Ohta (1983) also reported that H. macrochir is less tions from the DSRV Alvin on benthic fishes and abundant in Suruga Bay than the common halo selected larger in and near DWD-106. saur affinis. The population density Pages 432-450 in Baseline report of environmental conditions in deepwater dumpsite 106. NOAA of A. affinis reaches a maximum of about 23.2 Dumpsite Evaluation Report 77-1. Vol.2. individuals/1,000m2 between the depths of 1,172 Filatova, N.A. 1985. Halosaur fishes (Notacanthi and 1,716m. Sulak (1982) reported that H. formes) of the Indian Ocean. Vopr. Ikhtiol., 25 (5): macrochir was trawled in the western North At 728-740. (In Russian.) lantic from the depths ranging from 2,146 to Golovan, G.A. 1976. Rare and firstly recorded 3,094m and A. affinis from the depths ranging chondrostean and teleostean fishes of the continental from 1,239 to 2,354m. Though the bathymetric slope of West Africa. Trud. Inst. Okeanol., 104: range of H. macrochir slightly overlapped with that 277-317. (In Russian with English summary.) of A. affinis, these two species were not trawled Grassle, J.F., H.L. Sanders, R.R. Hessler, G.T. simultaneously at the designated depth range in Rowe and T. McLellan. 1975. Pattern and zona Sulak's survey (Sulak, 1982: 70). Thus, H. macro tion: A study of the bathyal megafauna using the research submersible Alvin. Deep-sea Res., 22: chir was not usually found in the same depth 457-481. range as A. affinis. Gilnther, A. 1878. Preliminary notices of deep-sea H. macrochir has a short based, single dorsal fishes collected during the voyage of H.M.S. fin, a long tail and an anal fin with long rays. Challenger. Ann. Mag. Nat. Hist., Ser. 5, 2: 248 Frequent photographic observations revealed that 251. individauls hover very close to the ocean bottom, Marshall, N.B. and D.W. Bourne. 1964. A photo facing into the bottom current with the tapered graphic survey of benthic fishes in the Red Sea and tail curved upward (Fig. 3). This hovering attitude Gulf of Aden, with observations on their popula was observed by Sedberry and Musick (1978), and tion density, diversity, and habits. Bull. Mus. is very similar to that of Aldrovandia affinis as Comp. Zool., Harvard Univ., 32: 223-244. McDowell, S.B. 1973. Suborder Halosauroidei. reported by Marshall and Bourne (1964), Stanley Pages 32-123 in D.M. Cohen and others, eds. Fishes (1971) and Ohta (1983). Undulation of the tail of the western North Atlantic. Mem. Sears Found. and anal fin causes the tapered tail to be curved Mar. Res., No.1, Pt. 6, xix+698pp. up and because of the hydrodynamics of its fin Ohta, S. 1983. Photographic census of large-sized pattern, the tail beat helps the to assume benthic organisms in the bathyal zone of Suruga a head-down attitude. Combined with infor Bay, central Japan. Bull. Ocean Res. Inst., Univ. mation on stomach content analysis (Sedberry and Tokyo, 15: 1-244. Musick, 1978) and submersible observation (Gras Paulin, C.D. and J.M. Moreland. 1979. Halosauridae

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of the south-west Pacific (Pisces: Teleostei: Nota トカ ゲ ギ ス 科 の 一 種 ク ロ オ ビ トカ ゲ ギ ス(新 称)の 日本 canthiformes). New Zealand J. Zool., 6 (2): 267 か ら の 記 録 271. 町 田 吉 彦 ・岡 村 収 ・太 田 秀 Sedberry, G.R. and J.A. Musick. 1978. Feeding トカ ゲ ギ ス 科 のHalosouropsis macrochirは 大 西 洋,南 strategies of some demersal fishes of the continental ア フ リ カ,イ ン ド洋,オ ー ス ト ラ リ ア 湾,ニ ュ ー ジ ー ラ ン slope and rise off the Mid-Atlantic coast of USA. ドお よ び 日本 か ら知 られ て い る.日 本 で はOhta(1983) Mar. Biol., 44 (4): 357-376. に よ り駿 河 湾 と相 模 湾 か ら初 め て 記 録 さ れ た が,標 本 の Stanley, D.J. 1971. Fish produced markings on the 分 類 学 的 記 載 は な か っ た.我 々 は 近 年 得 られ た 標 本 を 検 outer continental margin east of the Middle Atlantic 討 し,こ の 種 が 日本 の 中 部 か ら 南 部 に か け て の 太 平 洋 に states. J. Sed. Petrol., 41: 159-170. 分 布 す る こ と を 確 認 し,そ の 色 彩 的 特 徴 に 由 来 す る 新 和 Sulak, K.J. 1982. A comparative taxonomic and 名 を 提 唱 し た.本 種 の い く つ か の 計 数 形 質 に は 若 干 の 地 ecological analysis of temperate and tropical de 理 的 変 異 が み ら れ る.ト ロ ー ル で の 捕 獲 例 数 か ら判 断 し mersal deep-sea fish faunas in the western North て,本 種 は 日本 近 海 の1,500か ら2,700mの 海 洋 底 に Atlantic. Ph. D. Dissertation, Univ. of Miami, お い て さ ほ ど 稀 な 種 で は な い.深 海 カ メ ラ に よ る 駿 河 湾 Coral Gables, Florida, 181pp. で の 本 種 の 主 な 生 息 水 深 で の 推 定 密 度 は,西 部 北 大 西 洋 Wenner, C.A. 1978. Making a living on the continetal で の ア ル ビ ン号 を 使 っ て の 目 視 と 写 真 撮 影 に よ る 推 定 密 slope and in the deep-sea: Life history of some 度 と よ く似 て お り,主 な 生 息 水 深 は 両 地 域 に お い て よ り dominant fishes of the Norfolk Canyon area. Ph. 高 密 度 に 分 布 す る 本 科 の ト カ ゲ ギ ス の そ れ よ り深 い.本 D. Diss., College of William and Mary, Glouc 種 の 背 鰭 と臀 鰭 の 形 態,生 態 写 真 お よ び 食 性 か ら み て, ester Point, Virginia, 293pp. こ の 種 は 海 洋 底 に 強 く依 存 し た 生 活 を し て い る と 考 え ら れ る. (YM and OO: Department of Biology, Faculty of Science, Kochi University, 2-5-1 Akebono, Kochi (町 田 ・岡 村:780高 知 市 曙 町2-5-1高 知 大 学 理 学 部 生 780, Japan; SO: Ocean Research Institute, University 物 学 教 室;太 田:164東 京 都 中 野 区 南 台1-15-1東 京 大 of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 学 海 洋 研 究 所) 164, Japan)

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