May 19, 1982 - tangaroana was taken by m.v. Argo at NZOI Stn. Z2098 (28°39'S .... 1980: Study on the collection of Mr Victor Dan. (1). Descriptions of new ...
3
New Zealand Journal of Zoology, 1982, Vol. 9: 309-318
,""
.
Living Pleurotomariidae (Mollusca: Gastropoda) from the South Pacifie PHILIPPE BOUCHET BERNARD METIVIER Muséum National d'Histoire Naturelle 55 Rue de Buffon, 75005 Paris, France Abstraet Perotrochus caledonicus n.sp. is described from the upper bathyal south of New Caledonia, an old area that has remained stable over the past few million years, and P. tangaroana n.sp. is described from the bathyal of Lau Ridge. These represent the first occurrence of living Pleurotomariidae in the South Pacific; other representatives of the family are restricted to Southeast Asian seas or the Atlantic. Résumé Description de Perotrochus caledonicus n.sp. du bathyal supérieur au sud de la NouvelleCalédonie; l'espèce provient d'une région qui est restée stable au cours des derniers millions d'années. Description de P. tangaroana n.sp. du bathyal de la ride de Lau. Ces deux espèces sont les premiers représentants dans le Pacifique Sud des Pleurotomariidae, famille connue jusqui'ici d'Asie du Sud-Est et de l'Atlantique. Keywords Gastropoda; Pleurotomariidae; Perotrochus caledonicus; Perotrochus tangaroana; new taxa; extant slit shells; South Pacific; bathyal zone; bibliography.
:
309
INTRODUCTION Although fossil Pleurotomariidae have long been known in the Australasian region (e.g., Maxwell 1978); living representatives of the family have been recorded only from South-east Asia, the western Atlantic, and South Africa. This paper reports the occurrence of 2 new Perotrochus species in the bathyal zone of the South-west Pacific, and updates the list of literature on Recent Pleurotomariidae given by Bayer (1966).
Received 19 May 1982 J.
Genos Perotrochus Fischer, 1885
Perotrochus caledonicus n.sp. (Fig. 1, 2, 4D) Holotype and 4 paratypes: r.v. Vauban Stn 15 (22°49'S, 167°12'E), south-west of Ile des Pins, southem New Caledonia, 390-395 m, dredged alive, 10 April 1978 (holotype and 2 paratypes in MNHN, Paris; 1 paratype in Australian Museum, Sydney, No. C.133067; 1 paratype in National Museum of New Zealand, Wellington, No. MF.34176). Type data.
Material
specimens specimens specimen 167°09'E),
examined. Type series; 8 topotypic in museum collections; 4 topotypic in private collections; 1 additional from r.v. Vauban Stn 24 (22°48'S, 355-360 m, dredged 12 April 1978.
Description of holotype. Shell trochoid, grossly equilateral in out!ine, thin and light in structure, composed of 8.3 whoris with conspicuous spiral omamentation. Spire coeloconoid; apical angle of first 5 whorls 57°; mean spire angle 72°. Protoconch (940 IJ.om) a bulbous nucleus followed by 0.3 of a whorl which is smooth, glassy, and weakly de!imited from teleoconch. Protoconch followed by a white, finely granular whorl. Teleoconch sculptured by spiral cords crossed by finer collabral incrementallines, giving first 4 whorls a beaded appearance readily visible under the microscope. This appearance weakening on succeeding whorls as axial riblets become obsolete. Surface between growth riblets sculptured by fine, radiating threads (Fig. 4D). E~ly postlarval sculpture consisting of axial !ines above and below selenizone, in conjunction with suture and selenizone forming squarish to rectangular spaces. Axiallines each forming a knob just above suture in lower part of whorl; above selenizone, axial lines gradually becoming interrupted by a spiral keel, the two forming a knob where they intersect. Additional spiral keels later appearing both above and below selenizone, together with 1 median keel; axial ribs concurrently becoming more obsolete. Sculpture from 5th whorl on predominantly spiral, with 2, 1, and 2 ribs respectively above, on, and below selenizone. Third spiral keels appearing on 6th whorl above selenizone and on 7th whorl below it.
New Zealand Journal of Zoology, 1982, Vol. 9
310
Table 1 Measurements from specimens of Perorrochus caledonicus: AA, apical angle (0); AS, angle of spire (0); DSLM, depth of slit along lower margin (mm); DSUM, depth of~lit along upper margin (mm); H, height (mm); HBW, height of body whorl (mm); MaD, maximum diameter (mm); NW, number of whorls; WF, width of fasciole on body whorl (mm). Specimen no." and status 1. 2. 3. 4.
5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Holotype 22°48'S, 167°09'E
"b Paratype Paratype
"c Paratype aratype
f
".e
H 29.7 29.7 28.0 26.2 26.0 24.1 23.9 23.8 23.1 22.8 22.8 22.0 22.0 17.6 16.6 15.8
MaD HBW DSUM DSLM WF
NW
AA
34.0 30.5 33.0 29.0
19.0 17.1
26.8 25.4 27.8 26.1 25.6 25.4 24.0 18.9 17.4 16.0
8.3 8.5 9.0 8.5 8.0 7.3 7.8 8.0 8.0 8.0 7.8 7.8 7.8 7.3 7.0 7.0
57 56 55 61 58 59 58 57 60 60 60 55 54 53 59 56
-
20.5 20.0 -
13.8 13.1
15.2 15.3 15.1 14.0 14.4 13.8 13.2
15.7 14.5 14.0 -
9.1 10.0 9.2
10.9 10.0 -
7.5 7.2
-
16.7
-
-
-
12.8 12.8
-
-
9.2 9.0
1.6 1.2 1.2 1.0 1.3 -
-
1.3 1.0
-
-
-
-
-
-
5.9 6.2
0.6 0.6
AS 72
69 68 75 68 68 68 69 70 74 72
69 66 65 67 64
"In descendinAlsorder of shell hei~ht. "Body whorl broken. bOne-third of body whorl Measurements estimated (body whorl completely bromissing. lit damaged. ken). eprotoconch and early teleoconch coated with gold for SEM study.
Body whorl with 8 spiral cords above selenizone, 4 below, and 2 on fasciole; axial ribs obsolete here, but microsculpture of minute, diverging threads still present. Profile of whorls nearly straight, but weakly convex on last 2 whorls, hence spire slightly concave; sutures scarcely impressed, very inconspicuous. Selenizone in mid whorl in earlier part of shell, then gradually descending to lower two-thirds. Fasciole faintly concave, bordered by 2 inconspicuous keels and bearing both microsculpture of diverging threads and curved incremental lines; these lines sharp in upper whorls, weakening near end of 5th whorl, then becoming obsolete. A white, beaded spiral cord appearing in selenizone of 3rd whorl, then strengthening progressively and at whorl 5.8 losing its beading. Space between spiral cord and lower edge of fasciole widening shortly before 7th whorl; a second white, spiral cord appearing in first part of 7th whorl, weaker than the first at levelof open slit, but these cords dividing selenizone into 3 equal strips. Aperture horizontally oblong, the part above the slit running about 0.1 of a whorl further than the lower part. Slit short, 20.5 mm along its upper margin, Le., one-quarter the circumference of the
Flg. 1
last whorl. Columella and interior of aperture covered with a thin nacreous layer; base inside aperture with only a narrow band of nacre exposed, adjacent to suture. Columellar lip sharp, thin, with a moderate sigmoid flexure. Base almost flat, with a small, shallow umbilical depression; umbilicus aImost completely closed, consisting of a tiny slit between base and nacreous columellar fold. Base dirty white, with a few faint growth lines not intersecting the 21 rounded spiral cords. Shell otherwise pale beige-orange mottled with brownred, tending to crimson on final whorl and lower part of earlier whorls. Spiral cords unicolorous dirty white. Operculum aImost circular, multispiral; each whorl with a conspicuous free margin. Radula (Fig. 2) composed of 5 distinct groups of teeth on either side of the single rachidian, referred to as central, lamel1ate, hooked, brush, and flabelliform. Radular formula: R + 1 + 22 + 14 + 53 + 7. Right side of each row skewed anteriorly. Right central tooth more anteriorly situated than left central of same row, as shown by Hickman (1981, p. 190, fig. 1 and 2) for the radula of P. quoyanus (Fischer & Bernardi). Dimensions, Table 1.
Perotrochus caledonicus: A-C, holotype (29.7 x 34.0 mm); D, E, paratype (MNHN, 22.8 x 25.6 mm).
,,
312
New Zealand Journal of Zoology, 1982, Vol. 9 P. caledonicus also resembles the Caribbean P. amabilis (Bayer) in its rather thin and light trochoid shell with conspicuous spiral ornamentation, and in the sligl:ltly concave profile of the spire, but They are quite different in ail their other characters. Finally, caledonicus is akin to P. vicdani Kosuge from the Philippines. This species looks like a young hirasei in its shell shape, small size, and light construction. Its sculpture is stronger th an that of caledonicus, with spiral cords on the base that are intersected by the growth lines. Its colour pattern is very close to that of hirasei, and quite different to that in our new species. P. caledonicus has been taken in the same area as Lepidosphaera hindei Lévi & Lévi (1979, p. 443), a demosponge with affinities in the Eocene of New Zealand. The northern part of Norfolk Ridge has the same basaltic structure as western New Caledonia, and has subsided at least 400 m since Miocene times (Daniel et al. 1976). Anglada et al.
Remarks. Other adult specimens examined fit the description of the holotype. Sorne shells have an orange hue on the central part of the basal dise, and juveniles are more pointed in outline. Perotrochus caledonicus has the same general outline as P. hirasei (Pilsbry) (Fig. 4C), but has a thinner, lighter shell which differs in sculpture and colour. In caledonicus the streaks of colour are not crimson, are less copious, and are limited to the part of the whorls below the selenizone; the spiral cords are white. In hirasei the upper surface is copiously streaked with crimson, as are the spiral cords, and the base has flexuous reddish streaks. In caledonicus the periphery is a little more angular, and the white spiral cords and the few faint incremental !ines do not make the base of the shell granular as in hirasei. Although the spiral cords are similar in number in the two species, they are stronger and much more widely spaced in hirasei; the axial riblets cross them, and produce a cancellate surface with raised beads at the points of intersection. In hirasei there is also a difference in the sculpture above and below the selenizone not apparent in caledonicus. The selenizone is larger and more clearly marked in hirasei.
~ Radula of Perorrochus caledonicus, drawn from scanning electron micrographs (x 145 approx.). Only the right half-row and beginning of the left are shown.
Fig. 2
Bouchet & Métivier-Living Pleurotomariidae (1975) have studied sedimentological processes south-west of Ile des Pins, showing that the paleobathymetry of the area has been rather stable during Plio-Quaternary times. The area is probably an old structure, and it may not be totally irrelevant that several 'living fossils' have been found there.
Perotrochus tangaroana n.sp. (Fig. 3, 4A,B) Type data. Holotype: NZOI Stn P947 (25°14'S, 179°04'W), Lau Ridge, 547-646 m, dredged alive on pumice substrate from r.v. Tangaroa, 1 June 1980 (New Zealand Oceanographie Institute, Wellington, No. H.368). Material examined. Holotype and probable worn juvenile (Fig. 4A,B) (see under 'Remarks'). Description of holotype. Shell moderately large, broadly trochoid, thin, composed of 8 whorls. Apical angle of first 4 whorls 77°; mean spire angle 88°. Protoconch eroded; first whorl whitish, very worn. Teleoconch sculptured by spiral cords crossed by incremental riblets, the two forming squarish, rectangular spaces with knobs where they intersect, giving first 4 whorls a beaded appearance readily visible under the microscope. Spiral cords becoming obsolete on later whorls between suture and selenizone. ShelJ surface sculptured by numerous microscopie, diverging threads between the arcuate growth riblets. Second whorl with 2 spiral cords on subsutural part, 2 more or less fused cords on suprasutural part, and no cords on selenizone. More spiral cords appearing gradually, until at end of fourth whorl there are 4 spiral keels above selenizone and 4 below. Regularity of sculpture then interrupted by a repaired breakage. Subsutural sculpture from fifth whorl onwards consisting only of numerous sinuous, weak axial riblets and obsolete spiral threads; suprasutural sculpture consisting of numerous axial cords interrupted by 7 spiral ribs, the two forming a knob where the y intersect, to give a delicate beaded appearance. Shell broken and repaired at end of eighth whorl, just before slit, resulting in partial disruption of ornamentation and colour. Profile of earlier whoris nearly fiat, but last 3 whoris increasingly convex, with sutures impressed. Fasciole close to mid whorl in earlier part of shell, then descending to lower two-thirds in body whorl. Selenizone not concave, but appearing a little sunken because it is bordered by 2 raised lines, marked by close-set, backward-curving incremental lines, and with only faint spirallines on penultimate whorl, where it is 3.6 mm broad.
313 Aperture subcircular, just a !ittle broader than high. Slit short, 36 mm along its upper margin, i.e., about one-sixth the circumference of the body whorl; edges thin and fragile, slightly chipped. Interior of aperture lined with iridescent nacre, more thinly in parietal area. Inner lip thickened; basal portion lined with a nacreous layer; upper part sharp and thin. Umbilicus closed, the hollow umbilical region bearing a rather large, pearly callus. Base moderately convex, with very numerous faint incremental !ines and 38 almost non-granular spiral striae. Shell pale reddish pink, slightly iridescent above fasciole and paler in suprasutural part of whorl; base rosy cream with reddish flammules. Operculum pale brown, multispiral; each whorl with a conspicuous free margin. Dimensions: height 58.5 mm; maximum diameter 69.0 mm; height of body whorl 40.8 mm; depth of slit along upper margin 36.0 mm, along lower margin 27.9 mm. Remarks. Perotrochus africanus (Tomlin) is similar to P. tangaroana but its shell is more depressed, with more convex whorls, including the earlier ones. Both above and below the selenizone the shell is yellowish-red, and is sculptured with fine, papillate spiral cords and regular axials. P. teramachii Kuroda is also similar to P. tangaroana, but the shell has a higher, more conical spire, deeper sutures, and conspicuous cancellate sculpture immediately above and below the selenizone. It is dark orange with irregular red stripes and a few white spots. The base is strongly convex, with about 60 nearly non-granular striae. What appears to be a worn juvenile of P. tangaroana was taken by m.v. Argo at NZOI Stn Z2098 (28°39'S, 173°01'E) on the Betty Guyot, northern Three Kings Rise, at 841 m in September 1967. It is 13.8 mm high and has a maximum diameter of 18.5 mm (chipped). It is a rather low, trochoidal shell consisting of 6 whorls. The apical angle of the first four whorls is 80°, and the mean spire angle is 90°. The sculpture and position of the selenizone fit the description of the holotype. Samples are from loca!ities so widely scattered over the Indo-West Pacifie that the possibility of P. teramachii, P. africanus, and P. tangaroana representing peripheral populations of a single clinally variable species cannot be excluded. Perotrochus species certainly have non-planktonic larval development, so that local populations will tend to produce geographically identifiable 'forms' or 'races'. The apparent disjunctness of extant Pleurotomariidae may, however, not be totally a result of insufficient sampling effort, but rather an indication of the relict distribution of an old
314
New Zealand Journal of Zoology, 1982, Vol. 9
Fig. 3
Perorrochus rangaroana, holotype (58.5 x 69.0 mm).
Bouchet & Métivier-Living Pleurotomariidae
315
~
Fig.4 A, B, Perotrochus tangaroana (NZOI Stn Z2098; 13.8 x 18.5 mm). C, P. hirasei (off Meshima Iighthouse, Danzyo Is, Kyushu; NSMT 56631,48.0 x 59.0 mm). D, P. caledonicus, detail of sculpture, 3rd whorl of teleoconch (x45).
316 evolutionary Iineage. If this is so, genetic exchange between the different groups of populations does not take place and teramachii, africanus, and tangaroana are valid, isolated species. Only the sympa tric or definitely allopatric occurence of these taxa, determined (perhaps fortuitously) from further samples, will reveal the truth of the matter.
ACKNOWLEDGMENTS
The New Caledonian material was collected during biological operations conducted by Office de la Recherche Scientifique et Technique Outre Mer, Nouméa. We thank Bruce Marchall (NMNZ), who first pointed out to us the small specimen of Perotrochus tangaroana, and Ken Grange (NZOI), who generously presented the holotype for description. Tadashige Habe (National Science Museum, Tokyo) sent juvenile P. hirasei on 10an. Patrick Anseeuw kindly compared this material with his extensive private collection of Pleurotomariidae. The SEM is by Centre de Microscopie du CNRS, and the photos are by Alain Foubert.
REFERENCES
Anglada, R.; Froget, C.; 'Recy, J. 1975: Sedimentation ralentie et diagenèse sous-marine au SE de la Nouvelle-Calédonie (Dolomitisation, ferruginisation, phosphatisation). Sedimenrary geology 14: 301-317. Azuma, M. 1964: Notes on the radula of Perotrochus africanus (Tomlin, 1948). Venus 22 (1962-63) (4) : 350-355. 1969: On sorne gastropod mollusks from the Taiwan Straits (Part 1), mainly description of radulae. Venus 28(2) : 89 - 98. Barnard, K. H. 1963: Notes on the animais of Gyrina gigantea (Lam.) and Pleuroromaria africana Tomlin. Proceedings of the Malacological Society of London 35 (1962-63) (4) : 155 -158. Bayer, F. M. 1963: A new pleurotomariid gastropod trawled in the straits of Florida by RN Gerda. Bulletin of marine science of the Gulf and Caribbean 13(3): 488-492. - - - - 1966: New pleurotomaTÜd gastropods from the western Atlantic, with a summary of the recent species. Bulletin of marine science of the Gulf and Caribbean 15(4) [1965]: 737 -796. 1967: Another new western Atlantic gastropod. Bulletin of marine science of the Gulf and Caribbean 17(2) ; 389-397. Bouvier, E. L.; Fischer, H. 1898: Etude monographique des Pleurotomaires actuels. Archives de zoologie expérimentale, 3' ser., 6: 115 -180. Chung, N. 1975: Three look-alike rare slit shells. Hawaiian shell news 23(11) (n.s. 191) : 3. Cross, E. R. 1971a: The Pleurotomariidae. A survey of the known living species. Hawaiian shell news 19(8) (n.s. 140) : 1 and 14. - - - - 1971b: The case history of the pleurotomariids. Their geoJogical history. Hawaiian shell news 19(8) (n.s. 140) : 1 and 14.
New Zealand Journal of Zoology, 1982, Vol. 9 Daniel, J.; Dugas, F.; Dupont, J.; Jouannic, c.; Launay, J.; Monzier, M.; Recy, J. 1976: La zone charnière Nouvelle-Calédonie - Ride deNorfolk (S. W. Pacifique) - Résultats de dragages et interprétation. Cahiers ORSTOM, série géologie 8(1) : 95 -105 Fretter, V. 1964: Observations on the anatomy of Mikadotrochus amabilis Bayer. Bulletin of marine science of the Gulf and Caribbean 14(1) : 172 -184. - - - - 1966: Biological investigations of the deep sea. 16. Observations on the anatomy of Perotrochus. Bulletin of marine science of the Gulf and Caribbean 16(3) : 603-614. Habe, T. 1962: C%ured illustrations of the shells oflapan, Vol. II. Osaka, Hoikusha. Habe, T.; Kosuge, S. 1964: A Iist of the Indo-Pacific molluscs, concerning to the lapanese fauna: (1). Superfamily Pleurotomarioidea. Oce. No. 55629, National Science Museum, Ueno Park, Tokyo, lapan. Hickman, C. S. 1981: Evolution and function of asymmetry in the Archaeogastropod radula. Ve/iger 23(3) : 189 -194. Hirase, S.; Taki, 1. 1954: An illustrated handbook of shells in natural colors from the Japanese islands and adjacent terri tory. lapan, Maruzen Co. Kira, T. 1961: Coloured illustrations of the shells of lapan. Enlarged and revised edition. Osaka, Hoikusha. 1962: Shells of the western Pacific in colour. Osaka, Hoikusha. Kosuge, S. 1972: Slit shell (Gastropoda, Mollusca) of the world. Narural Science and Museums, Tokyo 39(12): 1-20. 1975: Note su alcuni molluschi dei mare della Cina Orientale. La conchiglia 7(81-82) : 10 -14. - - - - 1980: Study on the collection of Mr Victor Dan (1). Descriptions of new species of the genera Perotrochus, Angaria and Latiaxis. Bulletin of the [nstute of Malacology, Tokyo, 1(3): 37-39. Kosuge, S.; Suzuki, M. 1969: Entemnotrochus rumphii (Schepman, 1879), newly collected from the South China Sea. Venus 27(4) : 155 -158. Kuroda, T. 1955: A new Pleuroromaria from Japan with a note on a specimen of P. rumphii Schepman collected from Taiwan. Venus 18(4) : 211-221. Leme, J. L. M.; Penna, L. 1969: Ocorrência de Mikadorrochus no Brasil, corn descriçao de uma nova espécie (Gastropoda, Pleurotomariidae). Papéis avulsos de zoologia 22 [(1968-1969) (21) : 225 - 230. Lévi, C.; Levi, P. 1979: Lepidosphaera, nouveau genre de Démosponges à spicules en écailles. Bulletin de la Société Zoologique de France 103(4) (1978) 443 -448. Matsurnoto, N. 1929: On the Japanese species of the genus Pleuroromaria, with the description of the radula of P. hirasei Pilsbry. Venus 1 [1928-1930) (4): 136 -140. Maxwell, P. A. 1978: Taxonomic and nomenclatural notes on sorne New Zealand Cenozoic Mollusca, with descriptions of new taxa. New Zealand journal of zo%gy 5(1) : 15 - 46. Morrison, R. W. 1971: The case history of the pleurotomariids. The discovery of the living Pleurotomariidae. Hawaiian shell news 19(8) (n.s. 140) : 1 and 14.
:
Bouchet & Métivier-Living Pleurotomariidae Nieuwenhuis, J. G. B. 1975: Recente Pleurotomaria's in Nederlandse Verzamelingen. Correspondentieblad van de Nederlandse Malacologische Vereniging 166: 431-434. Okutani, T. 1969: Distribution of Perotrochus beyrichii. Venus 28(1) : 53 - 56. - - - - 1972: Molluscan fauna on the submarine Banks Zenisu, Hyotanse, and Takase, near the lzuShichito Islands. Bulletin of the Tokai Regional Fisheries Research LaboralOry 72 : 63 -142. 1975: Gümpse of benthic molluscan fauna occupying the submarine Bank Kurose, near Hachijo Island, Japan. Venus 33(4) : 185 - 205. ----1979: A new pleurotomariid gastropod from the Pacific waters off Honshu, Japan. Venus 38(3) : 159 -165. Pilsbry, H. A. 1903: A new PleurolOmaria. Nawilus 17(3) : 36. - - - - 1903: A new Japanese PleurolOmaria. Proceedings of the Academy of natural sciences of Philadelphia (1903) : 496. Rios, E. de c.; Matthews, H. R. 1968: Nova espécie de Pleurotomariidae do Brasil. Arquivos de la Estaçl10 de Biologia Marinha de la Universidade Federal do Cearà 8(1) : 65-{j8. Shikama, T. 1961: On Mikadotrochus salmiana found off Chôshi, East Japan. Venus 21(4): 500-506.
317 - - - - 1964: Selected shells of the world illustrated in colours. Vol. Il. Tokyo, Hokurya-kan. 1973: Description of new marine Gastropoda from the east and south China Seas. Science reports of the Yokohama National University, section 2, biological and geological sciences 20: 1-8. 1977: Descriptions of new and noteworthy Gastropoda from western Pacific and Indian Oceans. Science reports of the Yokohama National University, section 2, biological and geological sciences 24 : 9 - 23. Shikama, T.; Horikoshi, M. 1963: Selected shells of the world illustrated in colours. Tokyo, Hokuryu-kan. Tan, T. H. 1974: A preliminary study of the anatomy of Pleurotomaria rumphii Schepman, 1879. Bulletin of the Chinese Malacological Society 1 : 15 - 20. Tomlin, J. R. le B. 1948: A new s"pecies of PleurolOmaria. Journal of conchology 23 /1948-1954J (1) : 2. Wang, C. Y.; Pan, Y. P.; Tang, B. Y. 1976: Scanning electron microscope study of the radular teeth of Pleurotomaria rumphii Schepman. Bulletin of the Chinese Malacological Society 3 : 5 -12. Yamashita, H.; Habe, T. 1969: East China Sea, a new locality of Perotrochus teramachii Kuroda. Venus 27(4) : 153 -154.
