The malacologicalsocietymalacological society of Japan
llreVoLVEN L]S (Jup. Jovr. Malac.) 51. No. 4 (1992}:235 268
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[]i l9g {} rt., rtJ..Z- za ll (MSIil Zone Noteworthy Gastropods Colleeted from Bathyal in Tosa Bay by the RIV Kotaka-MaTzL in 1987 and 1988 Takashi OKuTANI and Akiko IwAHoRl Tokyo 108 and (Tokyo Univesity of Fisheries, Konan, Minato-ku, Tokyo 112) Japan Women's University, Mejirodai, Bunkyo-ku, m) 18 Abstract: Among the gastropod specimens trawled from bat,hyal depths (450-780 tosaensis Neptunea kotakamaruae, species were identified. Four species, namely, Eosipho to be new species. Morphological Antiplanes delicatus, and Eipergo nipponensts are recognized of "rare'' species, e.g. Otukaia kiheiziebisu, characters, particularly radula, and distributions Ptychosinynx bisinua- Orectospira tectijbrmis. 7)'ephonopsis sayoae, Buccinum koshikinum, fauna in Tosa Bay seems to ta japonica among others are discussed, Bathyal gastropod and undercurrent. represent a mixture of faunlllae of intermediate (slope) water Introduction 1960; Nakayama, Tosa Bay has been famous for a rich molluscan fauna (Azuma, extended to shallow depths or 1965). However, more intensive collecting effort has been molluscan fauna in this bay has seldom at best to shclf zone than deep water, thus deepsea collections et al., 1963). The RfV been explored except a report of sporadic (Horikoshi made an in- Kotaka-Maru, Nansei National Fisheries Research Institute at Kochi, recently there tensive trawling down to 8oo m in Tosa Bay to clarify demersal finfish fauna (Horikawa et al., 1991). mollusks were incidentallycaught During such series of trawl samplings, interesting for us through the courtesy of Mr. Hiroshi and many gastropod specimens were supplied a lightupon bathyal Horikawa of that Institute. The investigation on this material throws of soft facies. Among them, some molluscan fauna of Tosa Bay, particularly bottom "rare" species may noteworthy. Here, in- range extentions and mass occurrences of be depth of 450 m are reported. teresting gastropods collected from deeper than the NII-Electronic LibraryMbrary Service The malacologicalsocietymalacological society ofJapathof Japan 'vENUS: 236 Vol. 5t, Ne. 4 (1992) Materials Out of the KOtaka-Maru collection 'specimens 455 gastropod from nine haulstreatedmade in deeper than 450 m to 780 (down m) during 1987 and 1988 are selectively here (Fig. 1, Table 1). N 133` 13.l-E Koch; SHIKOKU 33"3or 33N Nif Asizuri Fig. 1 Sampling site of the RfV Kotaka-?Lclaru in Tosa Bay. (Stippled area with depth contour from 4oo to 800 m) Table 1. Date, depth and number of gastropod specimens under the present study (R/V Kbtdka-Mliru) ' ' Haul nuMber uSed Depth range Date Numbers of specimen in this paper of haul under examination 1 Sept, 2, 1987 630-670m 96 2 OcL 6, l987 450-500 15 3 Nov. 17, 1987 600 50 4 Nov. 24, 1987 780 151 5 Jan. 26, 1988 700 15 6 May 14, 1988 7oo 30 7 June 21, 1988 700-720 32 8 Sept, 13, 1988 750 62 9 Sept. 21, 1988 750 1 ' tt ' NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 237 Okutani･lwahori: Bathyal Gastropods from Tosa Bay Taxonomy Family TROCHIDAE Rafinesque, 1815 1. Bathybembix aeola (Watson, 1879) (Figs. 2-6) Materiai: 14 specimens from Haul 3 (600 m); 32 from Haul 4 (780 m); 16 from Haul 8 (750 m). The largest specimen measured 49.95 mm in length (height) and 38.7 mm in width. The ratio of LIW is 1.23 (N=10). The soft part has a small nuchal appendage behind the right eye. The radula is rhipidoglossate, co.3.1.3.eo (oo ti 19) (Fig. 4). The length of radula ribbon central is variable, but approximately 10(7b of shell length and bearing 40-50 rows. The tooth has a broad base with triangular lateral projections and a strongly incurved central cusp of which both lateral margins are serrated. The lateral teeth are also monocuspid and finely serrated in both sides (Fig. 5). The marginals are thin sickle-shaped and serrated (Fig. 6). Remarks: Among the radula of the Tribe Calliotropini Hickman & Mclean, 1990, this species may have a good size of rhachidian in comparison to, such as, CZitliotropis Seguen- za, 1903. Hickman (t981) discussed the functional morphology of radula of this species and assumed that B. aeota performs selective deposit feeding. Distribuiion: This species was originally collected from the HMS Challenger St. 232, off Enoshima Islet, Sagami Bay, 345 fathoms, and St. 235, the Sea of Enshu-Nada, southern the coast of Middle Honshu, 565 fthoms. Since then, this species has been known from Sea of Kashima-Nada (Taki and Otuka, 1942) in 60-100m (Kira, 1954). Okutani (1964) collected this species by the RfV Sqyo-Maru from Sagami Bay and the Sea of Enshu-Nada, at depths between 500 and 1,020 m. Although Kuroda et al. (1971) gave the range of "off Horikoshi this species Shikoku", the only precise locality data from Tosa Bay are by Hakuho-Mar". This et al, (1983) from Tosa Bay, 707-750m (40 specirnens) by the R!V Tosa Bay tending species thus ranged from off the Sea of Kashima-Nada down south to to deepen the habitat soytherly. Otukaia ktheiziebisu (Otuka, 1939) (Figs. 7-13) 700 m). Material: One specimen from Haul 5 and 7 specimens from Haul 6 (both Except for the size and a considerable variability in numbers of spiral ribs mentioned NII-Electronic Library Service The malacologicalsocletyofmalacological society of Japan 238 VENUS: Vol. 51, No. 4 (1992) Figs.2-6.Bathybembix aeola (Watson) J'"U T] St"f:fi trJ ]tr"d 2, Shell length 49.9 mm; 3, SI. 33.4 mm; 4. A part of radula ribbon (scale=1oo "m); S. CentTal and lateral teeth, cnlarged (scale=50 ptm); 6. LaLeral and marginal teeth, enlarged (scale=1oo "m). 4-6 all from SL 21.35 mm. NII-Electronic Library Service The malacologicalsocletyofmalacological society of Japan Okutani.Iwahori: Bathyal Gastropods from Tosa Bay 239 Figs.7-13.Otukaia kiheiziebisu (Otuka) ce'xNl V'Jz ifJiL b"i 7. Shell length 26.7mm; 8. SL 26.5 mm; 9. Illustration in the original description by Otuka (1939); 10. A part of radula ribbon (scale=1 mm); 11. Central and lateral teeth, enlarged (scale=1oo ptm); 12, 13. Marginal teeth, enlarged (scale=IOO pm). 10 from SL 26.15 mm, 11, 13 from SL 22,8 mm, 12 frorn SL 20.05 mm. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 240 VENUS: Vel. 51, No.4(1992) below, the present materials well agree with the original description of Otuka (1939 as Calliostoma). The size of the specimens under examination ranged from 12.3 mm to 26.7 mm in shell length (height) and LIW from O.898 to 1.007 (mean O,966). The primary spiral keels, which are usually wealky beaded or finely crenulated, on the penultimate and body whorls are three including the basal peripheral one. In some specimens, such as the one from Haul 5 and 3 specimens from Haul 6 have strong secondary spiral ribs intercalated. Espe- cially, a specimen measuring 23.5 mm in shell length from the latter lot has 5 equally strong spiral ribs on the body whorl representing a different appearance from the typical form. In such a multi-ribbed specimen bears stronger secondary cords which are primarily emphasized tertiary cords. The base is ornamented by 18 to 20 strong spiral cords with narrow interstices. The radula is rhipidoglossate, co.4.1.4.oo (Fig. 10). The central tooth has a thin, strongly bent cusp which is finely serrated laterally. Lateral teeth are also strongly bent and serrated like the central tooth (Fig. 11). The marginal teeth may be ciassified into one innermost, 8 inner and about 35-40 outer marginal teeth. The innermost marginal tooth has rather robust shaft, thick base and 4-5 short cusps along the incurved distal portion. The inner marginals are thinner than the innermost marginal and tend to weaken outwardly and have 8 comb-like cusps on both sides. Thc outer marginals have a slender shaft and incurved cusp which is elaboratedly serrated (Figs. 12, 13). Remarks: This species was originally described by Otuka (1939) based on the specimen from a depth of 600 m in the Sea of Kashima-Nada. Although the type specimen (Reg. No. 500 Earthquake Research Institute, Tokyo Imperial University: Fig. 9) was destroyed during the war, the subsequent specim ¢ n in the Kawamura Collection, now stored in the National Science Museum Tokyo, which sN'as illustrated by Okutani (1983), was compared for identit'ication. Ikebe (1942) established Otukaia for this deepsea, thin-shelled, and sparsely ribbed Cal- liostomatin. The present study reports for the first time the radula of this "rare'' species and clarifies that it is typical for the Calliostomatinae Thiele, 1924 (Hickman & McLean, 1990).Distribution: "from Ikebe (1941) gave the occurrence of this species the Sea of Kashima- Nada, 6oo m deep and off Misaki, Sagami Bay, 50-60 fathoms'', However, the occurrence of this species in Sagami Bay has nor been verified since. The present discovery Figs. 14--17. Phanerotepida transenna (Watson) }7 VV'7.f>'Y g Ob"l 14. Shell length 25.3 mm; 15. Apart of half radula ribbon (scale=1oo pam); 16. A part of radula ribbon (scale=5oo ptm); 17. Central tooth, enlarged (scale=100 pam). 15-17 all fTom SL 25.3 mm. Figs. 18-20. 0rectospira tectijbrmis (Dall) Y lfJz.i7 7 )7 Jl:b;E V 7tr'1 18. Shell length30.5 mm; 19. Apart of radula ribbon (scale=:500 gem); 20, Central and lateral teeth, enlarged NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Okutani.: BathyalGastropods from Tosa Bay 241 NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 242 VENUS: Vol. 51, No.4(1992) of O. kiheiziebisu from a bathyal depth (700 m) is noteworthy, because no record between the above-mentioned range and the present locality has been available. Family TURBJN[DAE Rafinesque, 1815 3. Phanerolepitla transenna (Watson, 1879) (Figs. I4-17) Material: One specimen from Haul 3 (600 m) and 1 specimen from Haul 5 (700 m). For reference, more 5 specimens from 1990 survey (Tosa Bay, 650-708 m and 750-804 m) were investigated. The shell length (height) ranged from 22.7 to 25.3 mm (N=5), and the mean LIW was O.929. The epipodial lobe is poorly developed. The radula is rhipidoglossate, oo.5.1,5.eo(eo =16-18) (Fig. 16). The central tooth is ovoidal in shape with incurved top on which seen is the peg-like secondary cusp with com- plicated structure (Fig. 17). The lateral teeth have an overhanging cusp which is finely serrated. The shaft has roundly expanded laterally, ovcrlaps and interlocks with the ad- joining one, more distinctly in inner laterals than the outer ones (Fig. 15). The marginals are 17 in number in average, and it is simple, flat but narrow, with incuryed top. Remarks: Hickman and McLean (1990) found that the radula of the Subfamily Collonii- nae Cossmann, 1916 to which the genus Phanerolepida Dall, 1907 belongs, is of the primi- tive turbinid type with overlap and interlock systems in basal lateral teeth. The genus Phanerolepida was monotypic before Hickman (1972) found an Oregon Oligocene species. P. oregonensis. Distribution: The holotype was collected from the Challenger St. 235 in the Sea of Enshu- Nada (Watson, 1879) and then from Albatross Sts. 4972 (440 fathoms) and 4973 (600 "off "olT fathoms). Dall denoted Yokohama, Japan'', but it is not accurate because Yoko- hama" means Tokyo Bay as was interpreted by Hickman (1972). However, Tokyo Bay is a shallow embayment having no such a great depth. Both Albatross stations are located in the Sea of Enshu-Nada, quite close to the C7iallenger stations. Habe (1961) stated that this species lives in Sagami Bay, 200-500 m deep, probably based on the data on the label of the Kawamura co]lection. Okutani (1964) first reported 16 living and 10 empty shells of this species from 7 stations between 550 and 800 m in Sagami Bay, and later (1966, 1968) 6 spccimens and 2 empty shclls from 4 stations between 620 and 1,020 m in the same bay and a station of 620-720 m deep off Izu-Oshima Island. Tsuchida (1985) recently verified the occurrence of this species in the Kii Channel, 778-1,112 m deep and off Kochi (Tosa Bay) 714-735 m. There- fore, along with the present occurrence of this species in Tosa Bay at 600-804 m deep, the geographical range of this species by Okutani (1969) and Hickman (1972) should be extended. The bathymetrical range of P. transenna seems to be 550 to 1,100 m. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Okutani.Iwahori: Bathyal Gastropods fTom Tosa Bay 243 Family ORECTOSPIRIDAE Kuroda, Habe & Oyama, 1971 4. 0rectospira tectijbrmts (VVatson, 1880) (Figs. 18-20) Materiat: 32 specimens from Haul 4 (700 m); 3 from Haul 5 (700 m); l3 from Haul 8 (750 m). The very characteristic conchological profile well agrees with description and illustra- tion of Basitissa (Orectospiav babelica Dall, 1925 which has been synonymized with Et]hineUa tectEfbrmis Watson, 1880 by Tsuchida (1986). The largest specimen in the present material measures 32,2 mm in length and LIW is 1.397 (1.239-l.692, N=12). The radula is taenioglossate, with the formula 2.1.1.1.2 (Fig. 19). The central tooth is low trapezoid in shape with an incurved central cusp, which is triangle in frontal view and it is finely scrrated laterally. The denticles are counted about 20 each. Lateral tooth is strong, parallelogramatic in outline, with a curved cusp which is scrrated proximally. The shaft has a strong ridge that creates longitudinal cleft-like groove (Fig. 20). The margi- nal tecth are slender and sickle-shaped, with a shallow groove medially. Remarks: This species has long been known as O. babelica (Dall, 1907) that was thought to be separated from O. tectCtbrmis (Watson, 1880). However. Tsuchida (1986) clarified that Dall's babelica is the older specimen of Watson's tect(fbrmis and these two namcs represent only two different growth stages of a single species, O. tectijbrmis which has a priority. Instead, a small species which had been thought to be O. tectijbrmis (Habe, 1961 ; Okutani, 1964, 1968; Kuroda et al., 1971) had a fQssil name O. shikoensis (Yokoyama, 1928) (Tsuchida, 1986). The genus Orectospira Dall, 1925 (originally a subgenus of Basilisstij has hitherto been placed in the Subfamily Orectospirinae of either the Family Turritellidae (Habe, 1957) or the Family Cerithiidae (Abbott & Boss, l989) by the most of modern workers, although it was raised to the familial rank by Kuroda et al. (1971). Distribution: O. tectijbrmis was first collected from the Chaltenger St. 235 in the Sea of Enshu-Nada, 1,033 m deep, O. babetica was from Atbatross Stations 4972 and 4973 off Kii Peninsula, 804 m and 1,097 m. Tsuchida (1986) analyzed the all available data ot' cotle ¢ tions (Watson, 1886; Dall, 1907; Horikoshi et al., 1983; Tsuchida, 1985) including his new data and concluded that this species lives in depths betwccn 700 m and 1,100 m in the area extending from the Sea of Enshu-Nada to Tosa Bay. It is clearly separable in habitat from O. shikoensis, which centers in 300-6oo m deep (range 150-760 m) from Sagami Bay to off Kii Peninsula. Therefore, the present collection seems to cut the shal- lowest and western limit of the distributional range of this species. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 244 VENUS: Vol. Sl, No. 4 (1992) Family NATICIDAE Gray, 1840 5. Lunatia plicispira Kuroda, 1961 (Figs. 21-22) Material: One specimen from Haul 6 (700 m). ' It is a Polinicin of middle size. A sole specimen examined measures 18.85 mm in length and 19,55 mm in width. The concho]ogical feature that is well characterized by possession of crowded subsutural pleats (raised growth lines) is not conflicting with the original description. The radula is taenioglossate, 69 in number of transverse rows with the formula 2.1.1.1.2 (Fig. 21). The central tooth is low trapezoid in shape with basal auriculations on both sides, and it has incurved top with three cusps among which the central one is the largest. The lateral tooth is parallelogramatic in shape, with a strong cusp that carries a few small denticles on both sides. Marginals are sickle-shaped, but the inner marginal has a cusp-like projection in the middle (Fig, 22). Remarks: ]t is somewhat close to L. paUldd (Broderip & Sowerby, 1829), which is a Subarctic species but invaded into the bathyal depths in Sagami Bay together with some other benthos of the Subarctic origin (Okutani 1964, 1972). However, as was pointed out in the original description, subsutural pleats of growth lirae and thick, rusty periostracum separate this species from the others. The type specimen has never been illustrated. The specimens illustrated by Azuma (1960) and Kuroda et al. (1971) have much taller shell than the present specimen (L!W=O.96). The one of the refercnce specimens examined by us had a value of LIW greater than 1.3. A large series of specimens exhibits a considerable infraspecific variation in respect to L/W ratio. A sole specimen under this study seems to haye especial- iy low spire. The radula of this species was illustrated by Azuma (1961) and Inaba (1976). Azuma described that the central tooth has 3-4 denticles on both sides of the central cusp. Inaba 'stated that there are 1 to 4 denticles there. The bifid appearance of the inner lateral is in common with many other Polinicins. Distribution: The type locality is Tosa Bay. This species has been known mainly on upper to lowcr shel[' (50-450 m) on the Pacific coast from Sagami Bay to Tosa Bay (Kuroda, 1961 ; Azuma, 1961; Okutani, 1964; Kuroda et al., 1971; lnaba, 1976; Okutani et al., 1988) and the western part of Japan Sea (Ito, 1967). The present occurrence is the deepest record of this species. 6. Lunatia yokoyamai (K"roda & Habe, 1952) (Figs. 23-26) Materiat: One secimen cach from Hauls 4 and 5 (700 m); 4 frem Haul 7 (700-720 m); 2 t'rom Haul 8 (750 m), NII-Electronic Library Service The malacologicalsocietymalacological society ofJapanof Japan Okutani.Iwahori: Bathyal Gastropods Collected from Tosa Bay 245 $l .1ge / ai''V)' Figs. 21-22. Lunatia plicispira Kuroda l- S?'71 SffK 21. A part of radula ribbon (scale=100 ptm); 22. Halt' row, enlarged (sacle=100 prn). Both from SL 18.85 mm, Figs. 23-26. Lunatia yokoyamai (Kuroda & Habe) H rt'r? Stv?'71 9Jtl"( 23. SheH length 14.45 mm; 24. A part of radula ribbon (scale=100 pam); 25. Lateral tooth, enlaTged (scale=10 ptm); 26. Central tooth, enlarged (scale=10 pm). 24 from SL ll.15mm, 25-26 from SL l3.5mm. NII-Electronic LibraryMbrary Service The malacologicalsocietymalacological society of Japan 246 VENUS: Vel. 51, No.4(1992) The shell is rather thin, ivorish in color with a brownish periostracum. The umbilicus is broadly open. A small species measuring 9.3 to l4.45 mm in height with mean L/W --- being 1.02 (N 7), The radula is taenioglossate, with 60-65 transverse row and formula 2.1.1.1.2 (Fig. 24), The central Looth is trapezoid carrying an auriculated projections on both sides of thc basc. The top is everhanging with three cusps of whieh the central one is thrice larger than lateral ones (Fig. 26). The lateral Looth is irregularly parallelogramatic in outline, having a sharp cusp on the curved top accompanied by small dcnticles of which number varics frorn two to t'our by specimen or even by the place of a radular ribbon (Fig. 25). There is a bay below the major cusp. The marginals are sickle-shaped, but the outer tooth has a bifid tip but the outer one has a single cusp. Remarks: The spccics name was proposed by Kuroda and Habe (1952) for the shell that "Polinices had been misidentified by Yokoyama (1920) as paUidus". The true L. paUida (Broderip & Sewerby, 1829) has thinner periostracum, small spire, less constricted suture and narrower umbilicus, and it lives in the Subarctic waters. The radula of L. yokayamai was oncc described by Azuma (1961) who emphasizes the character of the lateral tooth that has a yery prominent cusp dirccted almost downwards. Distribution: The 11rst discovery of this species by Yokoyama (1920) was a Pliocene fossil from Koshiba where diverse sublittoral and shelf mollusks occurred. Both Azuma (1960) and Nakayama (1965) reported this species l'rom Tosa Bay (5-20 m) and its neighborhood. Azuma's (1961) specimen was from Mikawa Bay (where fishery catch from outside of the "South bay is lailded). Kuroda cL al. (1971) gave the range of this species of Boso Peniun- sula, Henshu and Shikoku and the Japan Sea, 50-200 m". Therefore, the present finding from depths of 700 m revealed that t.his species has a wide bathymetrical range extending frem sublittoral down to bathyal depth. Family MURICIDAE Da Costa, 1776 7. 1'rophonopsis soyoae Okutani, 1959 (Figs. 27-29) Materiai: Two specimens t'rom Haul 5; 8 from Haul 8 (both 700 m); 4 from Haul 7 (700-720 m); 6 from Haul 8 (750 m). i) Figs. 27--29. 1'rophonopsis soyoae OkuLani .7'?1'7.7 1' i tz b"6 27. Shcll length 28.8 mm; 28. SL 3e.3 mm; 29. A of radula ribbon ' part {seale-IOO "m) froni SL 30.3 mm. Flgs. 30-32. Bathyancistrotepis trochoideus (Dall) fi･'7'"i 30. Shell length 24.g mm; 31, A part of radula ribbon (scale=100 ptm) from SL 21.55 mm; 32. The same frorn SL 24.7 mm, showing infraspecific varia- bilities in numbers of cusps of both central and lateral teeth. Fig. 33. Eosipho tosaensis n. sp. Holotype, shell length 34,1 mm. v"Jt'7A.N"i CXffl･ili-.) NII-Electronic Library Service TheThemalacological malacological society of Japan 247 Okutani･Iwahori: BathyalGastropodsCollecLed from Tosa Bay NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 248 VENUS: Vol. 51, No.4(1992) ' The shell length was measured on all 20 specimens and ranged from 22.75 mm to 30.9 mm. The L/W ranged from 2.11 to 2.69 (mean 2.37). Sex of 18 specimens out of 20 was determined: 10 males and 8 females. The male has a huge penis behind the right cephalic curves to the tentacle. It right and downwards and is almost equal in width in entire rength with a papilla-like projection on the tip. The radula is rhachiglossate, 1.1.1. in dental formula. The central tooth has a rather narrow base with blunt basal projections and it has the largest conical central cusp followed by thick and rather irregularly conical outer cusp and the smallest and skiny conical cusp between them, The lateral teeth are boomerang-like in shape with a curved monocuspid tip (Fig. 29). Remarks: Every conchological character, particularly very crowded (about 70) axial riblets that are thinly edged and partly wrinkled, well agree with the original description by Okutani But, the (1959). present specimens are taller than the holotype specimens (LIW=2.11) and has more distinct peripheral rib. The radular character is similar to those of a closely related species, Tlrophon multigra- dus Houart, 1990 from New Caledonia, particularly in possession of a single middle ctrsp on the central tooth, in spite of the fact that the number of middle cusp is variable among Muricid genera. This New Caledonian species is certainly a South Pacific congener of the present species. Distribution: A sole record of this species since the original description was by Matsumoto from (1979) a depth of 500 m off Owase, the southeastern coast of Kii Peninsula, close to the type locality, the Sea of Kumano-Nada, 2,OSO m deep. The present finding is a range extention of this exquisite Trophonin down south to Tosa Bay and also proved that the bathymetrical range up to 700 m there. Fami}y BUCCINIDAE Rafinesque, 1816 8. Bathyancistrolepis trochoideus (Dall, 1907) (Figs. 30-32) Materiat: Two specimens frorn Haul 5 and 3 from Haul 6 (both 700 m);9 specimens from Haul 7 (700-720 m)J The shell is short biconic with strong spiral ribs with many secondary riblets between them. The largest specim ¢ n (female) measured 25.35 mm in shell length and the smallest one 14.05 mm. The ratio IVW is 1.26 (N=14). The penis is curved and thicker and wider distally ending with a pustulate projection at the tip. . The radula is rhachiglossate with a formula 1.1.I. The radula ribbon measured 4.0-6.7 mm in Length carrying 76-90 transverse ro-,s (N =3), The central tooth has a quadrate base with concave base line. Thc number of cusps varied from 3 to 5, of which thc NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Okutani.Iwahori: Bathyal Gastropods Collected from Tosa Bay 249 central one is usually strongest of all. However, the numbers vary even within a single radula ribbon from 4 to 5 among which the distalmost one is usually tumid. The lateral tooth has two major cusps of which the outer one is far stronger than the other, but usually bears one to two smaller cusps between these major cusps (Figs. 31, 32). Remarks: Habe and Ito (1968) established the genus Batlryancistrolepis typifying ChrysodO- mus troehoideus Dall. 1907 largely based on the difference of radular character from that "the of Ancistrolepis grammatus (Dall, 1907), which is not the type species but typical member'', particularly in possession of small denticles between large inner and outer cusps of the lateral tooth. In fact, radulae illustrated by Azuma (1965), Okutani (1966), Habe & Sato <1972) and Bouchet & Waren (1986) all have these denticles, but they seem to be not so far weaker than those in the radula of A. grammatus (Habe & Sato 1972). Tiba and Kosuge (1986) claimed that this difference may warrant of infrageneric. The central tooth of the radula illustrated by the previous workers rnentioned above usually has very tumid three cusps. But, the present observation clarified that these cusps vary from 3 to 5 by specimen. Habe and Ito (1965) separated a thick-ribbed forms from shallow water (100-500 m) in the Pacific coast of Northeastern Honshu a subspecies ovoideus, because the type locality of trochoideus was Atbatross Sts, 4972 and 4973, off Kii Peninsula, 804-l,097 m. However, Okutani (1966) and Tiba and Kosuge (1986) demonstrated a wid ¢ polymorphic variation between the typical one and ovioideus throughout geographical and bathymetrical ranges. Distribution: Since Dall collected this species by the Atbatross, Okutani (1959) found this species from abyssal depth (2,050 m) in the waters near Kii Peninsula. Okutani (1964, 1966, 1968) frequently reported this species from Sagami Bay and Izu Islands area, 550-1980 m deep. Ohta (1983) reported this species from Suruga Bay, 276-823 m deep, and Tsuchida (1983) first discovered this buccinid whelk from Tosa Bay, 707-750 m (which well agreeable with the present study) along with Sagami Bay (750-1290 m), the Sea of Kashima-Nada (615-2,050 m) and Sanriku (northeast Honshu) coast (1,270-1,625 m). The large popu]ations from lower shelf off the Sea of Kashima-Nada in incidental catches of commercial trawl have been well known (Habe & Ito, 1965). In summary, B. trochoideus is distributed on the Pacific coast of Japan extending from the northeastern Honshu down south to Tosa Bay via Sagami Bay, Suruga Bay and off Kii Peninsula, in lower shelf, bathyal and down to upper abyssal zone, about 2,OOO m. 9. Eosipho tosaensis n. sp. (Fig. 33) Materiat: A single specimen from Haul 4 (780 m). Diagnosis: A small buccinid with thin shell and moderately long siphonal canal. Perios- tracum thick and velvetty. About 20 axial ribs, of which shoulder one is angulated, crossed by several spiral primary cords and many secondary ones. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 250 VENUS: Vol, 51, No.4(1992) Deseription: The shell is obese fusiform, thin and pure white in color. The surface is covered by a thick, velvetty periostracum of ochre color. The protoconch is almost eroded but seemingly has 2 turns. The teleoconch consists of at least 4 whorls, which are ornamented with crowded axial ribs crossed by spiral ribs. The number of axial ribs are 20 on the penultimate whorl and 21 on the body whorl. The primary spiral cords are 5 in number on the penultimate whor], among which the one on the shoulder is strongest of all creating an acute shoulder and the others are also emphasized on the axial ribs. There are more secondary spiral cords both on the broad sutural ramp and between primary ribs. The base is rounded and has more than 20 primary and secondary spiral cords even on the strongly constricted siphonal canal which is slightly recurved backwards. The aperture is widely pyriform and white within. The outer lip is thin and crenulated in accordance with external cords. The inner and columellar lips are gently curved, The operculum is horny, yellowish with nucleus downwards. Animal was not examined. Measurements: Length 34.1 mm, width 19.0 mm (Holotype: NSMT-Mo' 69668). Remarks: The present new species seems to be the closest kin to Eosipho coriolis Bouchet & Waren, 1986 from the South China Sea, 856-884 m deep, particularly in an obese fusi- form shell. However, E. coriolis has a thick shell with more crowded and stronger axial ribs. Distribution: Only a single specimen has been known from the type locality (Tosa Bay, 780 m deep). 10. Aulaeofusus calhiaeus (Dall, 1907) (Figs. 34-38) Material: Two specimens from Haul 6 (700 m) and 3 from Haul 7 (700-720 m). The largest specimen measured 51.2 mm in length. The L/W ratio is 2.31 (N=5). The she]1 is fusiform and rather thin. Eight to nine spiral ribs, which are wider than the inter-rib grooves, are present on the penultimate whorl. The periostraeum is thick and olive-colored. The body whorl occupies about 60glb of the total length with a strong con- striction towards the base. The operculum is slightly smaller than the aperture. The penis is flat and wide. The radula is rhachiglossate with the fermula 1.1.1. The central tooth has almost rectangular base and 3 cusps of subequal size (Fig. 36). A single specimen has an accessory denticle on the side of the left lateral cusp representing 4-cuspid tooth (Fig. 38), The prominency (height and width) of every cusp slightly varies by specimen. The lateral teeth have two cusps. Both cusps are usually of similar size. But, outer arch of the inner cusp occasionally carries minute denticle (Fig. 37). Remarks: Shikama (1962) had separated coarsely ribbed population as a subspecies, hitunei. ' National Science Museum Tokyo, Mollusca (Catalogue number of the Department of ZooLogy) NII-Electronic Library Service The malacologicalsocietymalacological society ofJapanof Japan Okutani.Iwahori: Bathyal Gastropods Collected;fTom Tosa Bay 251 'wrdiL . ... Ni'"'7Aix"i Figs.34-38. Autaeofitsus calmaeus (Dall) ?je l' 34. Shell length 50.8 mm; 35. SL 51.2 mm; 36-38. A part of radula ribbon (scale = 1oo "m) showing infraspecific variabilities in cusps of eentral and lateral teeth. 36 from SL 16.5 mm, 37 from SL 41.6 mm, 38 from SL 51.2 mm. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 252 VENUS: Vol. 51, No.4(1992) Kuroda and Habe (in Habe, 1961) established a closely related species A. coerulescens from shallow waters (100-200 m) in Tosa Bay. The separation of these taxa from A. calmaeus is very subtle. The type locality ofA. catmaeus is Okhotsk Sea in 682 fathoms (Dall, 1907). The present finding seems to represent one of undercurrent elements of the Subarc- tic origin (Okutani, 1968, 1972), 11. IVleptunea kuroshio Oyama, 1958 (Figs. 39-42) Material: 12 specimens from Haul 2 (450-5oo m); 3 from Haul 3 (600 m); 6 from Haul 8 (7SO m). The largest specimen measured 79.1 mm in length. The shell is obese fusiform (LIW := 1.91, N=9) with large mammillated protoconch. The teleoconch whorls are ornamented with 3-5 primary spiral ribs with intercalated cords. Growth line never raised. The shelly matter is white to pinkish. The animal is dark pinkish with sparse black maculations on foot and siphon. The penis is large, abruptly widened and thickened distally. The tip is obliquely truncated or slightly concave in the middle, The radula formula is 1.1.1. The radula ribbon measured about 20 mm in length and carries 92-117 transverse rows (N=3). The central tooth is quadrate but deeply concaye at the base. The cusps are 3 or 4 of similar size. The lateral teeth are sickle-shaped, larger than the central tooth, with strong outer cusp and 3 inner cusps of similar size (Figs. 40, 41). The right lateral has only 2 inner cusps in one of the specimens under examination (Fig. 42). Remarks: Kuroda et al, (1971) stated that the species name minor Hirase, 1908 (C)Iir)Lsodomus intensculpta m.) was preoccupied by Link, 1807, consequently, the replacement name is IVL kuroshio Oyama, 1958. However, the name NL kuroshio appeared in a nomenclatural note on IVL yokayamai Kuroda, 1954 with no description nor citation of the reference. Perhaps, Kira (1959) may be the right author who first gave a brief description, locality and illustration under this name. The radula of this species is typical for the genus. After Habe (1958) reported the radula of this species from Tosa Bay, he (1992) recently published electronmicrograph of the radula removed from large specimens (L=85.3 mm, 77.4 mm) from Sagami Bay. Figs. 39-42. ?Vkrptunea kuroshio Oyama L7=.1/'")titi?`e Fje 39. Shell length 75.0 mm; 40-42. A part of radula ribbon (seale=50 pam) showing infraspecific variabilities in numbers of cusps of both central and lateral teeth.fVeptunea Figs. 43-45. kotakamarz(ae n, sp. -ShjtY"dt7 (grit) 43. Shell length 74.0 mm; 44. Holotype, SL 98,95 mm; 45. A part of radula ribbon (scale=ilOO pam) from SI. 34.1 mm. NII-Electronic Library Service The malacological societysocietyof of Japan Okutani.Iwahori: Bathyal Gastropods Collected fromTosa Bay 253 NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 254 VENUS: Vol. 51, No.4(1992) In Tosa Bay specimen in his report, the lateral teeth are asymmetrical having 3 cusps on one tooth and 4 on the other. One of the Sagami Bay specimens has 4 cusps on the central tooth, but the othef has 3 cusps in rather abnormal arrangement, There are con- siderable infraspecific variabilities, 12. IVeptunea kotakamaruae n. sp. (Figs. 43-45) Material: Two juveniles from Haul 4 (700 m); 1 juvenile from Haul 7 (700-720 m); 1 from Haul 9 (750 m); 1 from Haul 10 (675-708 m). One empty shell for reference from a haul from a depth of 700 m on December 21, 1979. Diagnosis: Neptunea with tall spire ornamented by regularly spaced, strong spiral ribs that are 5-6 in number on penultimate whor], Shell thin, pure white, with thick, velvetty periostracum of ashy brown. Siphonal canal rather long. Description: The shell is fusiform with lengthfwidth ratio being about 2, thin but solid, pure white, and covered with a thick, velvetty periostracum of ashy brown color. It ex- hibits axial pleats along growth lines, but it is easi]y stripped off when dried. The number of whorls are 7 including the large bulbous protoconch with 2 turns. The spires are tall, not so much inflated that the suture is shallow. The early teleoconch has 3-4 strong spiral ribs that become 5-6 on the penultimate whorl. Spiral ribs are round and so thick that the inter-rib grooves are deep and ornamented with very fine spiral striae that crossed by also fine growth lines semetimes exhibiting ex- tremely fine cancellated appearance. The body whorl occupies nearly 7007b of total shell length. Strong 5-6 spiral ribs are present thereupon followed by more than 10 similar ribs on the base diminishing prominen- cy towards the siphonal canal, The aperture is ovo-pyriform, with a thin outer lip which is erenulated in accordance with spiral ribs. The inner wall is pure white and shining. A thin and very pale orange callus is deposited on the inner and columellar lips. The columella is straight and continues to open siphonal canal which is slightly recurved backwards. The operculum is slightly smaller than the aperture, oval, brown, corneous with down- ward situated nucleus. The radula is rha ¢ higlossate with the formula 1.1.1 (Fig, 45), The length of the radula is 5.75 mm in the specimen with shell length 34.1 mm and has 84 transverse rows. The central tooth is quadrate (length/width = O.67) with deeply concave base and four similar sized, rather low cusps placed at subequal interval. The lateral teeth have three cusps of which the outermost one is far stronger than the other two which are similar in size. The concayity between the outermost cusp and the middle cusp is deeply arched. The basal length of the lateral teeth is almost the same with that of the central tooth. Measurements: Length 98.85 mm, width 44.7 mm (Holotype: NSMT Mo-69669); L. 55.4 NII-Electronic Library Service The malacological society of Japan Okutani･Iwahori; Bathyal GasLropods Collected from Tosa Bay 255 mm, W. 26.95 mm (Paratype: NSMT Mo-69670) ; L. 121.8 mm, W. 57.1 mm (empty shell). Locality: Tosa Bay, about 700 m deep. Remarks: This species is a deepsea representative under warm water derived from frater/intensculpta-complex. However, the members of this cold water species group usual- ly have brownish shell, filmy periostracum (if present) and irregular (both in prominency and interval) spiral ribs. This species is distinct frorn them in having white, thin shell with velvetty priostracum and very regular spiral ribs. Arctic shallow water species with strong ribs, such as AJL lyrata (Martyn, 1784) and N. decemcostata (Say, 1826) have much ･ stouter and brownish shell. 13. Buccinum koshikinum Okutani, in Okutani, Tagawa & Horikawa, 1988 (Figs. 46-52) Material: 96 specimens from Haul 1 (630-670 m) and 28 specimens frorn Haul 3 (600 m); 80 from Haul 4 (780 m); 16 from Haul 8 (750 m). This species is characterized by very thin walled, brownish-fleshy colored shell with well inflated whorls ornamentcd by crowded, sharp spiral cords of various preminency. Most of the specimens have 20-30 spiral cords on the penultimate whorl (Fig. 47), but the other has a rather strong peripheral rib (Fig. 46) er has so indistinct ribs that the shell surface appears almost smooth (Fig. 48). The colorations of the shell and aperture are also very variable. Both of the most specimens are pale brownish or fleshy or even with purplish hue. But. some have orange or pale yellowish coloration. Twenty specimens (10 males and 10 females) ranged from 26.2 mm to 50.85 mm were measured obtaining LIW being 1.88 with no apparent sexual difference. The animal is fleshy colored, but darkened at the head, foot and siphon. The penis is long with equal width through its length terminating in a pustulous process. The animal is fleshy colored, but darkened at the head, foot and siphon. The penis is long with equal width through its length terminating in a pustulous process. The radula is rhachiglossate, typical for the genus, with the formula l.1.1. The ribbon measured 10.0 to 14.4 mm in length carrying 61-72 transverse rows. The central tooth has an elongate quadrate base. Among 15 specimens examined, 9 have 4 cusps (Figs. 49, 50), 4 have 5 (Fig.51) and 2 have 6 cusps (Fig. 6). The number does not accord with shell size or sex. The tallness and sharpness of cusps are also variable by specimen. The lateral tooth has 3 cusps among which the outermost one is [ong and strongest followed by less slender innermost one. The central cusp is situated closely to the innermost cusp. Among 15 specimens only one specimen has exceptionally two middle cusps on only left side (Fig. 50). Remarks: So far observed, this species is very variable in color, external sculpture and even ccntral tooth. In the orignal description, superficial resemblance of B. acutispiratum NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 258 VENUS: Vol. 51, No.4(1992) (Dal], 1907) was referred, but Dall's species has a thicker shell with distinct axial ribs. Moreover, Masuda and Habe (1987) proved that it belong to the genus Reticubuccinum Ito & Habe, 1980 in possession of vestigeal cusps on the central tooth. B. koshikinum belongs to the species-group having a thin-walled shell with crowded spiral cords, such as B. pemphigus Dall, 1927, B. niponense Dall, 1907 among others. But, it is inconclusive what kind of phylogenetic relationship will lie among the genus Buccinum which usually exhibits an extensive polymorphism, Distribution: Since this species was described from off Koshiki Islet, west of Kyushu, about 450 rn deep, it was found that this is the most abundant whelk in bathyal depths in Tosa Bay. Besides the specimens under report, numerous specimens were trawled by the RIV Kotaka-Maru from the same depth zone. This species seems to be distributed in slope and bathyal zone (450-800 m) mainly around Shikoku and west Kyushu with a single record from off Mie Prefecture (Kimura 1992), 14. Buccinum leucostoma Lischke, 1872 (Figs. S3-56) Material: Three specimens from Haul 2 (450-500 m); 4 from Haul 3 (6oo rn). The largest specimen measured 78.0 mm in shell length. The ratio of LfW is 1.77 (N=4). The radula is rhachiglossate, with the formula 1.1.1 (Figs. 54-56). The central tooth is elongate quadrate with strong basal processes on both sides. The number of cusps are 6, but the length, prominency, and intervals are variable by specimen. The lateral teeth have 3 cusps among which the outermost one is the strongest followed by the innermost one. The middle cusp is smallest and usually single, but occasionally bifid. Distribution: This species has been known as the one of the commonest buccinid whelks in the shelf to upper bathyal zone in Sagami Bay and Suruga Bay (Kira, 1954; Kuroda et al., 1972; Ohta, 1983; Horikoshi et al,, 1983). Azuma (1960) and Nakayama (1965) al- ready reported the occurrence of this species from Tosa Bay, but from shallower depths (150-2oo m by Nakayama) than the present discoveries. Thus, the bathymetrical range of this specics in Tosa Bay seem to be from 150 m down to 600 m at best. Family TURRIDAE Swainson, 1840 15. Antiplanes delicatus n. sp. (Figs. 57-58) Materiat: Three specimens from Haul 6 (700 m); 4 specimens from Haul 7 (700-720 m) Diagnosis: Antiplanes with delicate shell barely covered by a thin, grayish periostracum and ornamented by crowded, very fine spiral striae below blunL peripheral angle. NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Okutani.Iwahori: Bathyal Gastropods Collected from Tosa Bay 259 Description: Shell is fusiform, with L/W being 2.53 (N=7). The protoconch is partially eroded, but rather high, mammillated, white. polished with 1.5 tums. The teleoconch whorls are turreted, conical, 8 in number, with a blunt angle on the periphery. They are covered by a thin, grayish pcriostracum which is mostly eroded off and remains only in patch. The sutural ramp is broadly slanting with very delicate spiral striae and opisthocyrt growth lines which are continuous to prosocyrt lines below thc periphcral angle whcrc they ovcrlie delicate, but more distinct spiral lirae. The base of the body whorl is also ornamented by these delicate spiral striae which are frequently interrupted by growth lines and occasion- ally undulating, The siphonal canal is moderate, open and weakly twisted. The aperture is fusiform, and white within. The outer lip is thin and weakly angulated at the extremity of the peripheral angle and has a shallow but distinct anal sinus. The inner to columellar lips are calloused. The operculum is slightly smaller than the apertural area, corneous, yellow, pointed downward. The animal is creamy white with short and obese cephalic tentacles but with no eye. The mantle margin is sinuous behind the right cephalic tentacle, The penis is very Iong and abruptly attenuated distally with a thin projection. The radula ribbon is small, attaining only 5{Ph of shell length with 25-29 transverse rows (Fig. 58), The radula formula is 1.0.1.0.1. There is a central cusp-like structure in the center, but this may not represent central tooth. The marginaL tooth is dart-like in shape, with a ridge creating a deep groove insidc bclow. Measurements: Shell length 33.4 mm, width 12.45 mm (cr) (Holotype: NSMT-Mo 69671); shell length 26.75 mm, width 9.95 mm (cr) (Paratype: NSMT-Mo 69672). Remarks: Recently, Kantor and Sysoev (1991) made a thorough revision on the genus Antiplanes Dall, 1902. The conchological and radular characters of the present specics well agree with this genus, particularly, Rectisutcus Habe, 1958 group. However, the present species is easily separable from any other known species in the Pacific in lacking a thick olive-colored periostracum and in possession of very delicate shell with rather long siphonal canal. We agree Kantor and Sysoev that the central formation of the radula does not represent the centraL tooth. It is evident that the genus Antiptanes is a representative of the subarctic elements, somc of which invaded down south to bathyal and abyssal habitat around Sagami Bay with the cold undercurrent. The present species may represent a speci- ation in the southern extremity of the distribution range of the common stock. Distribution; Tosa Bay, bathyal (around 700 m). Etymotogy: Based on a delicate-looking appearance of the present species in comparison to other known species of the genus. 16. Ptychosii:J,nx bisinuata J'aponica Okutani, 1964 (Figs. 59-61) Material: Three specimens from Haul 7 (700-720 m). NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 260 VENUS: Vol. 51, No.4(1992) This species has a solid and tall turreted shell. The protoconch of all specimens has been erode, but eight teleoconch whorls (which are also more or less water-worn) reamined. The shell length of three specimens are 36.6 mm (cr), 40.7 mm (unsexed) and 41,65 mm (a), respectively. The mean L/W is 2.88, The nodules on the periphery is 14 on the penultimate whorl. The spiral cords on the sutural ramp is very fine except a single subsutural one, which is almost keeled, and 1-2 below the row of the peripheral granules. The outer lip is thin and bisinuated with a rostration of an emphasized basal spiral cord. The siphonal canal is rather short and open. The animal is pale brown in color. The mantle edge behind the right cephalic tentacle is sinuated. The radula ribbon is 2.7 mm in length carrying 47-58 rows of toxoglossate teeth with the formula 1.0.1.0.1. The central tooth has a minute and sharp central cusp with a square but obscured base (Fig. 61). The marginal tooth is also monocuspid and has an elevated and twisted swclling extending from the base to the middle of the tooth creating a hollow below. In the frontal view of the marginal tooth is shoe-shaped, but in the lateral view it is triangular (Fig. 60). Remarks: The radula character of this species wei! agrees with that of P. bisinuata (Powell, 1966). Based on the general conchological similarity, Okutani (1964) regarded this taxon a subspecies of Martens' (1901) species from off East Africa, 818-1362 m deep. The present study will corroborate his view. As was suggested by Powell (1964) this also indi¢ ates a close alliance to Gemmula-group. Distribution: The holotype specimen (Geological Institute, the University of Tokyo RM 8838) was collected from the Sea of Enshu-Nada, Pacific coast of middle Honshu, 620 m deep. The present findings seem to be a new record since the original description. 17. Crassispira takeokensis (Otuka, 1949) (Figs. 62-64) Material: Three specimens from Haul 4 (780 m); 2 from Haul 5 and 3 from Haul 6 (both 700 m); 1 from Haul 7 (700-720 m); 3 from Haul 8 (750 m). All 12 specimens (containing at least 2 males and 3 femeles) were measured. The shell length ranged from 19.4 mm up to 28.8 mm. The mean L/W is 2.80. Figs. 57-58. Antiptanes deticatus n. sp. t X=-Y"l 7"tf'77'-i (entE) 57. Holotype, shell length 33.4 mm; 58. A part of radula ribbon (scale= 100 pam) from SL 26.75 mm. Figs. 59-61. Ptychosi,:ynx bisinuata japonica Okutani 7 S 7tf- t}' Y"-71C')V''r (paiin) 59. Shell length 41.65 mm; 60. A part of radula ribbon (scalc=50 pam); 61. Cusp of the central tooth (scale=10 -m). 60-61 from SL 41,65 mm, NII-Electronic Library Service The malacological society of Japan Okutani･Iwahori:BathyalGastropQds Collected from Tosa Bay 261 .Ikl/'tt tt y",,, t t///t tt tttt/ttt. ttttt/ ., ttttt l,/1{I,,/'I,1t tt /t//.t tttttttt ' ,;l. ,e lfl,I'i tt ,,tl,-1, ltt tttt tt//tIS tttt/t 61 NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 262 VENUS: Vol. 51, No.4(1992) The protoconch of all specimens has been eroded, while the teleeconch whorls are seven in number. The shell is covered by a palc olive-colored periostracum. The sutural ramp has weak but crowded opisthocyrt growth lines and an obsolete subsutural spiral cord which is barely defined by a fine spiral lira. Below the shoulder are present 14-16 (on the penultimatc whorl) oblique axial ribs, which are nodulous adapically, overridden by slender and crowded spiral cords, and tend to become weak and eventually obsolete adaperturally, The aperture is pyriferm, whitc within, with a short, open and feebly recurved siphonal canal. The anal sinus is distinct. The aperture is fusiform, with nucleus situated downwards. The animal is crcamy white. A slender brown line runs along a little inside the mantle margin. The penis is slender and attenuated distally. The radula formula is 1.0.0.0.1. The tooth is bicuspid with a large inner cusp and small outer cusp xNThich overlies the t'ormer (Figs. 63, 64). "Brachytoma" Remarks: takeokensis was originally dcscribed from a fossil bed at Tomiya Tuffaceous Sandstone on the seu-cliff at Tomiya, Boso Peninsula, where diverse bathyal gastropods including Phanerolepida transenna co-occurs, The type is 25 mm in length and 9 mm in width (LIW=2.78), The present specimens well agree with Otuka's description. Otuka first allocated this species in the genus Brachytoma Swainson, 1840 and Habe and Ito (1965) placed it in the genus Clathrodrillia Dall, 1918. But both genera are character- ized by having a strong varix either on the apertural edge or on back, and they are rather heavy built shallow species groups. The allocation in Inquisitor Hedley, 1918 based on a superficial alliance is still insufficient, because the radulae of inquisiior spp. illustrated by Powell (1966) never coinci'de with that of the present specimen. The present allocation of this species in the genus Crassispira Swainson, 1840 is based on the closeness of radular morphology to the members of the genus (Powell, 1966). But it is still tentative, as Crczs- sispira usually contains more stouter shallow water dwcllcrs. Distribution: Okutani (1964) reported this spccics from the Sea of Kashima-Nada, 870 m dcep, Sagami Bay, 740-1,030m deep, off Miyake Island, 1,230-l,350 m deep, and the Sea of Enshu-Nada, 620 m dccp, He quoted that the lot from the last mentioned locality "a was varictal form", whieh may represent a diffcrcnt species. Habe and Ito (1965) gave the distributional range of this species to be off Hokkaido and Northeast Honshu, 100-300 m deep. These data suggest that this species is a shelf species in the subarctic sea and tends to deepen the habitat to the south probably with the Oyashio undercurrent (Okutani, 1972). Figs. 62-64. Cr`zstsispira takeokensis (Otuka) E i･' iJ `e l- )t';tti7 , 62. Shell length 40.7mm; 63. A part of radula ribbon (scale=z100 ptm); 64, Marginal tooth, entarged (scale=50 ptm). 63 & 64 from SL 53,95 mm. jt"T r;t -it･ Figs. 65-66. theoidts nipt:,onensis n. sp. if 1･ F t'7 ;'- >" 7 li"l (-WEig) 65. Holotype, shell length 30.15 mm; 66. Two teeth of radula (scale== 100 "m) from SL 26.2 mm. NII-Electronic Library Service The malacological societysocietyof of Japan Okutani-Iwahori: Bathyal Gastropods Collected from TosaBay 263 3 NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 264 VENU,S: Vol. Sl, No. 4 (1992) 18. Slpergo (SPeoides) nipponensis n. sp. (Figs. 65-66) Material: One specimen from Haul 4 (780 . m); 3 from Haul 6 (700 m); 2 from Haul 7 (700-720 m). Diagnosis: Turrid with white shell and tall spire but short siphonal canal. About 20 slender and oblique axial riblets with no spiral sculpture except a crenulated subsutural cord. Anal sinus sha]low. Lateral radular tooth long and hollowed with a distal slit, Description: Shell is fusiform or biconic, thin but stout, pure white in color. The pro- toconch is white, subglobular with slightly rough surface because of partial erosion, and a single turn. The teleoconch whorls are turreted with a conic spire. The sutural ramp is concave and smooth except opisthocyrt grQwth lines that create an obsoletely crenulate looking subsutural cord. There are slender and oblique axial riblets below the sutural ramp, and they are sharply nodulous on the shoulderlperiphery. There are about 20 such riblets on the penultimate whorl as well as on the body whorl where the most adapertural ones become obscure. The base is gently convex and concave with no spiral sculpture at all. The siphonal canal short, open and feebly recurved. The aperture is pyriform and white within. The outer lip is thin with shallow but distinct anal sinus. Operculum is far smaller than the apertural area, fusiform, pointed, with nucleus situated downwards. The animal is creamy white. The cephalic tentacle is short and thick. Eyes seem to be absent. Mantle edge is sinuous behind the right cepharic tentacle. The penis is long and abruptly attenuated distally with a thin projection. The radula formula is 1.0.1.0.1. The radula ribbon is only about 6% of shell length, with 25-29 transverse rows. The central tooth is indistinct but has a cusp-like projection. The marginal tooth is knife-shaped, grooved longitudinally creating a slit at the inner distal end behind the sharp, needle-like cusp (Fig. 66). Measurements: Shell length 30.15 mm, width 10.9 mm (Holotype: NSMT-Mo 69673); she]1 length 27.75 mm, width 11.3 mm (Paratype: NSMT-Mo 69674). Remarks: This species is very much alike S. yoshidai Kuroda & Habe in Habe 1961. However, the latter is a shelf species characterizing by a brownish periostracum and less number of larger peripheral nodules (12). Powell (1966) considered speoides Kuroda & Habe, 1961 being the subgeneric rank of the genus Eipergo Dall, 1895. This species resem- "Pleurotomella" ble vit:go Okutani, 1966 from Sagami Bay, 1,47e-1,500 m, in respect to snowy white shell, but the latter, of which the generic assignment has not been settled, has less distinct pustules on the periphery. Distribution: Tosa Bay, bathyal, 7oo-750m deep. Discussion Among 18 gastropod species under study, occurrences of only 4 species had been reported NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 265 Okutani.Iwahori: Bathyal Gastropods Collected from Tosa Bay from Tosa Bay by Ki'ra (1954), Azuma (1960), Habe (1961) and Nakayarna (1965), whose specimens and information mostly camc from incidental catches of commercial fisheries, before Horikoshi et al. (1983) recorded 4 more bathyal species based on the samplings by the research vessels. koshiki- The new discoveries of Otukaia kiheiziebisu, 7lrophonqpsis sQyoae. Buccinum noteworthy as their occur- num and Ptystichosii:ynx bisinuata japonica in Tosa Bay are rences have been so rare that their distribution range has. never been known. of Four new species are also noteworthy. All of them seem to belong to the genera subarctic origin or of cold intermediate water elements, namely, Eosipho. IVlaptunea. An- include tiplanes and Spergo. The cold-water elements among the known taxa may dis- Aulacofusus, Bathyancistrolepis and Buccinum, that are of the subarctic origin and certain differen- persed to the south by the undercurrent. Some of such members exhibit a range, tiation at marginal area (either bathymetrical or geographical) of the distributional calmaeus such as, Batlryancistrolepis trochoideus oveideus and Autacofusus hiranoi topographi- (+ coenilescens). Observations on large series of specimens and consideration on merely cal and oceanographical backgrounds lead us to warrant them not a speciation but infraspecific variability. transenna, and Orectospira Bathybembix aeola, Otukaia kiheiziebisu, Phanerolepida tectijbrmis are endemic to the intermediate water along the slopes of Japanese mainland. Their distribution ranged from off Sanriku coast down south to Tosa Bay via Sagami m Bay, Enshu-Nada and off Kii Peninsula at around the depth between 400 m and 1,ooO or so. mixture of In conclusion, the bathyal gastropod fauna under the present study is a descended shelf species, undercurrent elements and those confined to the intermediate (slope) one is dominated water. It is expected that the fauna from shallower than the present that than bathyal zone will contain by warm-water (Indo-west Pacific) and from deeper more species of abyssal water. Research Acknowle(igements: - We are indebted to Mr. Hiroshi Horikawa, Nansei NationaL Fisheries for study. and Mr. Shuzo Institute at Kochi, for providing us with such a hardly obtainable material with the crew Kishida (now Seikai NFRi) of the same Institute for his warm cooperation of sampling species after the RfV of the RIV Kotaka-Maru. It is ouT honor to have named one of the new Tokyo Kotaka-Maru. Our heaTty thanks are due to Mr. Kenjiro Konno and Dr. Susurnu Segawa, study. We also owe UniversiLy of Fisheries, for various assist and encouragement during the present Numanami, HiToshi Saitoand Kotaro Tsuchiya many thanks to the post-graduate students, Hideki for their help and advice paTticularly in S.E.M. and photegraphic techniques and processing. nt si pt'dibeX*mbfiff"7tiLutnttsOXfifiGlhb"JLe:So(, 1987-1988tPe: ± imEab"4 1- p---?v-(･pt= 6 itt] H.taf) O t), zFcue4sOm-800ma)waNX}:oLi(diffleL te. pmEtst- iFtait 9 eelmas>452mats -C･, ei)li -,)tlJb£ t etL(L) EZiSSti.B-el8Ierfi]fEi itX:. ea) i ti,sutw YJ Nht-L6 t, 4 nt-C･,b) tiEelR[MGI.] NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 266 VENUS: Vol. 51, No.4(1992) lt S di t i!fulgLkS tL( L i itr. 1. Bath.vbembix aeota {Watson, 1879) 7V'iwje'>xlfxffi 2. 0tukaia kihei.'.iebisu (Otuka, 1939) }"--t V'=lf X7tr'l 3. Phanerotepida transenna (Watson, 1879) }pt ?'VIHi'>V]Vit'l 4. 0rectospira tectijbrmis (Watson, 1880) Vlfz[77V7)'O-=:e ]) O"i v?'7Y 5. Lunatia pfieispira Kurodn, 1961 jc- V' i 57 S 7;t'i 6. Lunatia yokoyamai (Kuroda& Habe, 1952) --"('t?S'?'71 5')7'.r ･7rt.1'77.t 7. 7}'ophonopsis soyoae Okutani. 1959 ]) ･i Vffi 8. Bathyancistrolepis tro(:hoidetts (Dall, 1907) ff'V7.x"i 9. Eosipho tosaensis n, sp. -n-E'7A!"i oui'lgl) -7kl "fi7A.x"i 10. Autacqfusus caimaeus (Dall, I907) 11. Neptunea kttroshio Oyama, 1958 t ?t ir.il'iS'7:E I"' 3i- 12. iVleptunea kotakamantae n. sp. ) S th i Y" Jtf 7 ouiL"EE) 13. Buccinum koshikinuni Okutttni, 1988 - )･ j(-!N"lt 14. Buccinttm leucostoina Lischke, 1872 X7V7bl!S'i 15. Antiplanes delieatus n. sp, t/ti.Y"X 7'f?tf'( (ltflle) 16. Ptychosit:J,nx bisinuata japonica Okutani, 1964 7S7tf'7 P'=i)i' 7tr'i (WiMO 17. Crassispira takeokensis (Otuku. 1949) E FU{1 l- V' iK7 18. tS?)ergo rltt'7>･ (SPeoides ) nipponensis n. sp. }-t･> te F teV .9V'i (avtldi) References Abbott. R. T. and Boss, K. J. 1989. A classijication of the iiving ua)llusca. 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