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Dr. Chong CHEN

Dr. Chong CHEN

Deep-sea biologist. Malacologist. Evolutionary biologist. "Mollusc collector", photographer.

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The C. Chen Collection: “Kogkhulion”

“Kogkhulion” (Greek: “Conch”) is a photographic reference to world molluscs using specimens from the C. Chen Collection; continually updated. Mouse-hover over an image will display the scientific name, clicking/tapping reveals the full image with a detailed species account. For a searchable version, click here.

Ficus investigatoris (Smith, 1894) <br /> FICIDAE<br /> -150~200m, In fisherman's net, Muttom, Kanyakumari District, Tamil Nadu, India, 2015/x, 130.0mm <br /> <br /> The "Bengal Fig" is a large and intricately sculptured ficid found exclusively in the Indian Ocean, ranging from Bay of Bengal to Mozambique; the type locality being "Off Ganjam coast, eastern India". For many years it was considered a rare shell as the main supply was by-catch from trawlers working off Somalia, but very recently fresh supplies have emerged from India and it has become much easier to obtain. In its natural habitat it is a locally common gastropod mostly seen on sandy to muddy bottoms of rather deep water around -100~400m, although occasionally it is found as shallow as -30m. Ficidae is considered to feed by swallowing small organisms with detritus and organic particles, though some claim they feed on echinoderms and polychaete remains have been detected in the digestive tracts of Ficus. The surface sculpture is characteristic and little-varied among individuals, although the shell width to height ratio varies considerably. Typical shell length around 100mm, very large specimens (as shown) are known to exceed 130mm. In "A Conchological Iconography: The family Ficidae" (2000), Varhaeghe & Poppe cited the authority of this species as "Smith, 1906", but this was due to a confusion between two references by the same author and it was actually described in 1894. The specific epithet refers to the H.M. Indian Marine Survey Steamer "Investigator" which collected the first specimens that became the basis of the original description.
Barnea dilatata (Souleyet, 1843) <br /> PHOLADIDAE<br /> -20~30m, Trawled in mud, West Phuket Island, Thailand, 1998/ii, 79.3mm <br /> <br /> The "Dilate Piddock" is a large burrowing pholadid with a rather wide distribution in the Indo-West Pacific, ranging from Japan to India to Australia. A common filter-feeding bivalve with a much larger body than the shell, it lives deeply buried in sand or mud in shallow water from intertidal down to about 20m deep. Its very long siphon (up to four times shell length), which it uses to feed, is considered a delicacy in some places. For example in Ariake Sea, Japan it is a famous local speciality and is widely harvested to be eaten either fresh or dried; although its numbers in that area appears to be diminishing in the recent years. The shell is very fragile and has one calcified accessory plate, the protoplax. The apophysis, spoon-like appendage serving as a point of attachment for the foot musculature, is very long and narrow. Typical shell length around 80mm, very large specimens may exceed 120mm.
Luria tessellata (Swainson, 1822) <br /> CYPRAEIDAE<br /> -5~10m, Dived, Oahu Island, Hawaii, USA, 32.2mm <br /> <br /> The "Checkerboard Cowrie" is a highly distinctive cypraeid with its four characteristic dark blotches on the dorsum. An exceedingly famous and much sought-after species, it is very variable in blotch development and is thus not easy to find a specimen with well-balanced 'checkerboard' pattern; it is also rather variable in callous development. An omnivorous gastropod, it lives under corals and rocks from rather shallow to moderately deep water ranging around -3~50m. Almost all specimens are from Hawaii where it is uncommon (live specimens becoming rarer recently) and it was once thought to be an endemic there. From the 1980s, however, a few have been taken live around Taiwan and more recently in the Philippines; its true range therefore appears to be quite wide. It appear to only occur in the deep water in the western Pacific and is extremely rare there; the name Luria lani (Raybaudi 1986) was given to the Taiwanese population but is currently regarded as a junior synonym. Typical shell length around 30mm, extremely large individuals are known to reach 55mm.
Calliostoma toshiharui Kosuge, 1997 <br /> CALLIOSTOMATIDAE<br /> -150m, By tangle nets, Aliguay Island, Zamboanga Peninsula, Mindanao, Philippines, 2003/viii, 44.4mm <br /> <br /> The "Toshiharu's Top Shell" is a large and spectacularly ornamented Western Pacific calliostomatid ranging from the Philippines to Borneo. It is characterised by two to three spine-bearing spiral cords just above the suture, although the development of spines vary among individuals. The whorls are strongly shouldered due to the spine-bearing cords being especially prominent and thus appear slightly concave. A rare species even in the usual dead collected condition, live taken specimens without significant damage (as shown) are very rare. Most likely a carnivorous grazer feeding on tissue of cnidarians like most calliostomatids, it inhabits rather deep water around -150~300m. Typical shell height around 35mm, extremely large specimens may exceed 50mm.
Tonna melanostoma (Jay, 1839) <br /> TONNIDAE<br /> -60~80m, In fishing net, Off Kakeromajima, Amami Islands, Kagoshima Prefecture, Japan, 2007/vi, 235.9mm <br /> <br /> With a unique dark aperture the "Black-mouthed Tun" is an unmistakable and extremely handsome tonnid ranging from southern Kagoshima Prefecture, Japan to New Zealand. It is not only the most coveted and sought-after tonnid species of all, but also a species of legendary fame and rarity among all shells. A very large tonnid with an average shell length around 220mm, extremely large specimens are known to exceed 300mm. Despite having a large size and being easily recognisable it is very rare across its rather wide range, especially adults displaying well the signature black mouth. Most specimens appear to originate from either southern Japan or around New Caledonia, although recently young specimens have been surfacing frequently from the Chinese coast. Young specimens lack the signature "black mouth" as that only develops as the snail matures, but the characteristic sculpture of alternating thick and thin spiral cords make them unmistakable still. The only species it may be mistaken with is its sister species Tonna hawaiiensis Vos, 2007 which is endemic to Hawaii and has been wrongly treated as the same species for many decades. Tonna hawaiiensis, however, is a much smaller species on average and never develops a fully black aperture to the extent of T. melanostoma even when mature. Like other tonnids it is a carnivorous and predatory gastropod inhabiting sandy to muddy bottoms and predominantly hunts holothurians (sea cucumbers), most likely nocturnally.
Cymbiola irvinae (E. A. Smith, 1909) <br /> VOLUTIDAE<br /> -120m, Trawled on sandy to muddy bottom, South of Mandurah, Western Australia, Australia, 78.3mm <br /> <br /> The "Irvin's Volute" is a solid volutid endemic to the western shoreline of Western Australia, Australia. A little-varied species in terms of patterning and form, but the extent of shoulder spine development is very variable from being completely smooth and spineless to having long and recurved spines. It is a rather rare and sought-after species that is usually dredged dead or crabbed, live-taken specimens are very rare. Although it closely resembles the much more common Cymbiola nivosa (Lamarck, 1804), that species has a much smaller protoconch and less dense shoulder spines (when present) which are always solid and not hollow like those of C. irvinae. A carnivorous and predatory gastropod feeding on other invertebrates, it inhabits sand or gravel bottoms of moderately deep water around -50~250m. Typical shell length around 100mm, extremely large examples are known to reach 130mm.
Perotrochus wareni Anseeuw, Puillandre, Utge & Bouchet, 2015 <br /> PLEUROTOMARIIDAE<br /> -350~450m, Dredged, Grand Passage, North of New Caledonia, 45.4mm <br /> <br /> The "Warén's Slit Shell" is a small pleurotomariid endemic to New Caledonia, characterised by a fine pustulose sculpture. For many years, it was considered to merely represent a 'pustulose form' of P. caledonicus Bouchet & Métivier, 1982 which occured allopatrically and shared with it similar size, colour, and shape. The type specimen of P. caledonicus, however, had smooth and unbeaded spiral cords; no clear intergrades between the two forms were known. Only very recently, a study using both morphological and molecular data finally revealed that the two in fact represent two distinct lineages and are separate species. The 'pustulose form' was therefore described anew, as Perotrochus wareni, shown here. Though the two species appear to occur allopatrically in New Caledonia, P. wareni is more common in the northern New Caledonia while P. caledonicus is predominantly found in the southern areas around Isle of Pines. They also differ slightly in depth preference, with P. wareni occuring mostly around 350m deep and P. caledonicus slightly deeper at around 400m. Furthermore, the range of P. wareni extends westwards to Lansdowne Plateau in the Coral Sea but the range of P. caledonicus does not appear to reach the Coral Sea at all. The population from Chesterfield Plateau in the Coral Sea, previously attributed to P. caledonicus, was revealed to be a further distinct species in the same study and was named P. pseudogranulosus Anseeuw, Puillandre, Utge & Bouchet, 2015. It inhabits hard substrates and is a carnivorous grazing gastropod feeding on demosponges. Typical shell length around 40mm but extremely large specimens may exceed 70mm. Though it is locally somewhat common, high quality specimens are uncommon on the shell trade market.
Perotrochus caledonicus Bouchet & Métivier, 1982 <br /> PLEUROTOMARIIDAE<br /> -350~450m, Dredged, Southwest of the Isle of Pines, New Caledonia, 50.5mm <br /> <br /> The "New Caledonia Slit Shell" is a small, lustrous pleurotomariid endemic to New Caledonia as its name suggests. For many years, this species was thought to occur in two forms with distinct sculpture -- a 'smooth form' with uninterrupted spiral cords and a 'pustulose form' with the cords divided into many conspicuous beads. Although no obvious intergrades were known, the two were similar in size, colouration and shape as well as co-occuring in similar areas and were thus assumed to represent a single species. A recent study using both morphological and molecular data clearly revealed, however, that the two in fact represent two distinct lineages and are separate species. The 'smooth form', as shown here, corresponds to the nominal P. caledonicus and is more common in the southern New Caledonia, though the distribution range does extend northwards up to the Grand Passage area. The 'pustulose form' was newly described as Perotrochus wareni Anseeuw, Puillandre, Utge & Bouchet, 2015; it is more common in the northern New Caledonia but also occurs in the south, and the range extends westwards to Lansdowne Plateau in the Coral Sea. These two species differ slightly in depth preference, with P. caledonicus occuring mostly around 400m deep and P. wareni mostly around 350m deep. The population from Chesterfield Plateau in the Coral Sea, previously also attributed to P. caledonicus, was revealed to be a further distinct species and was named P. pseudogranulosus Anseeuw, Puillandre, Utge & Bouchet, 2015. The name P. caledonicus therefore currently refers solely to the 'smooth form'. A carnivorous grazing gastropod, it lives on hard substrates and feeds on demosponges. Typical shell length around 40mm, extremely large specimens are known to exceed 65mm. Though it is locally not uncommon, high quality specimens are still uncommon in the international shell trade.
Bursa verrucosa (Sowerby I, 1825) <br /> BURSIDAE<br /> -25m, SCUBA dived, Raoul Island (Sunday Island), Kermadec Islands, New Zealand, 31.6mm <br /> <br /> With numerous black warts well-contrasted against a whitish-yellow background, the "Verrucose Frog Shell" is one of the most striking bursids of all. The shell form is little-varied, but the warts vary in strength among individuals, in many cases a series of warts are reduced to a simple 'dotted-line'. It has a much restricted distribution from southeast Australia to Lord Howe Island, Norfolk Islands, Kermadec Islands, and northern New Zealand. One of the rarest frog shells and specimens are much sought-after by collectors, especially those with large and well-formed warts. It inhabits sandy to muddy bottoms of shallow subtidal water around -10~40m deep, and is a carnivorous gastropod like other bursids, probably mainly feeding on polychaete worms. Typical shell length around 30mm, very large specimens may exceed 55mm. A monotypic genus Annaperenna Iredale, 1936 was once proposed for it, but is now regarded as a synonym of Bursa.
Mikadotrochus salmianus (Rolle, 1899) <br /> PLEUROTOMARIIDAE<br /> -250~300m, Trawled, Off Kashiwa Island, Kōchi Prefecture, Japan, 1983/v, 93.5mm <br /> <br /> The "Salmiana Slit Shell" is an elegant pleurotomariid with a blazing coluration and a characteristically tall spire, ranging from Honshu, Japan to Taiwan to Philippines. A much sought-after rarity, most specimens have generally come from Taiwan although recently Chinese fishermen have also trawled many (mostly poor) specimens from the East China Sea. It reaches the largest size in Tosa Bay, Japan where the shells are the thickest and with a rather pale colouration; the shells gradually thins down towards south with specimens from the Philippines being the lightest in build but with a dark colouration. Both Tosa Bay and Philippines specimens are still very scarce today, especially in large size, though in the East China Sea it is probably best described as uncommon. A carnivorous grazer feeding on sponges, it inhabits hard substrates of rather deep water around -100~400m. Typical shell length around 90mm, extremely large specimens are known to exceed 135mm. For many decades since its description it was confused with its congener Mikadotrochus beyrichii (Hilgendorf, 1877) due to the small quantity and poor quality of available specimens. As better specimens surfaced, however, its obvious differences with M. beyrichii quicky became apparent and it has become widely accepted as a valid species since the 1970s. A well-known synonym is Mikadotrochus schmalzi Shikama, 1961.
Tenagodus obtusus (Schumacher, 1817) <br /> SILIQUARIIDAE<br /> Almeria, Andalusia, Spain, 118.9mm <br /> <br /> Tenagodus obtusus is a curiously shaped slit-worm shell with the first few whorls coiled regularly but suddenly shifting to growing an uncoiled tube. It is mainly known from the Mediterranean Sea with specimens from Atlantic waters generally attributed to T. senegalensis (G. B. Sowerby II, 1876), although some authors claim that the two should be considered synonymous. Tenagodus senegalensis appear to have generally more tightly coiled earlier whorls, although they are quite variable indeed. It is an obligatory sponge commensal and spends the entire life inside the host sponge, in most cases Holoxea furtiva Topsent, 1892. More than one specimens is usually found together in a cluster within the sponge. Most of the shell is completely embedded in the sponge which provides shelter and protection, only the uncoiled tube extends out. It is found in intertidal and shallow subtidal waters down to about -50m, and is a filter feeding gastropod. There is a corneous operculum supported by a much reduced foot, which is heavily sculptured with opercular bristles, the form of which is an important taxonomic character in this family. It is very similar in general appearance to the Indo-West Pacific species T. ponderosus Mörch, 1861, but is usually readily distinguishable by the slit morphology -- the slit of T. ponderosus is a series of elliptical holes on the coiled whorls then gradually becoming denticulated and then finally smooth-sided at the uncoiled part, whereas that of T. obtusus is smooth-sided without denticulation throughout the entire teleoconch. Typical shell length around 100mm, extremely large specimens may exceed 160mm. Although generally a common species, it is uncommon to find one in good condition on the shell trade market.
Aplustrum amplustre (Linnaeus, 1758)<br /> APLUSTRIDAE<br /> Dived, Nuku Hiva, Marquesas Islands, French Polynesia, 19.9mm <br /> <br /> The "Royal Paper Bubble" is a most lovely aplustrid shell-bearing opisthobranch widely distributed across the tropical Indo-West Pacific. A carnivorous and predatory gastropod mainly feeding on polychaete worms, it inhabits fine sandy bottoms of shallow waters less than 15m depth and is common throughout most of its range. Generally instantly recognisable by its two characteristic broad pink bands bordered by black lines, but the pattern is actually somewhat variable, especially the thickness of black lines. Specimens from the Marquesas Islands (shown) appear to differ from all other by having much darker colouration and much thicker black lines. Typical shell length around 15mm, extremely large specimens may exceed 25mm. On a side note -- Voskuil (1995) separated from this species Aplustrum exquisitum (Voskuil, 1995) which has one thick black band, instead of two black lines and a white band, between the two pink bands; and tip of the columellar being bent slightly towards the right instead of left when viewed at the aperture view with apex pointed upwards. Aplustrum exquisitum is supposed to be endemic to Marquesas and co-exist with A. amplustre there. However, when one views sufficient material, it appears that A. exquisitum is most likely merely a form of A. amplustre with an uncommon pattern, as a whole range of intermediates can be found in Marquesas.
Buccinum viridum Dall, 1889<br /> BUCCINIDAE<br /> -800m, Trawled, Off Astoria, Oregon, U.S.A., 43.5mm <br /> <br /> The "Turban Whelk" is a deep-water buccinid native to the northern Pacific, best known from the West coast of North America. Although generally an inhabitant of sandy to muddy bottoms of deep water around -700~2500m, it is also an important member of chemosynthetic ecosystems off off California and Oregon, USA, being commonly found in hydrothermal vents (e.g., Explorer Ridge), methane seeps, and on whale falls. It is a carnivorous gastropod but also scavenges when the opportunity arises. There are two forms, one with an obvious spiral cord on the shoulder and the other with a rounded shoulder. Though supposedly a common species, it is quite an uncommon species in the shell trade. It is the type species of subgenus Viridibuccinum. Typical shell length around 40mm, very large specimens may exceed 60mm. A similar species, Buccinum thermophilum Harasewych & Kantor, 2002 is known from the Endeavour Vent Field, Juan de Fuca Ridge, and differs from B. viridum by smaller, narrower, more higher spired shell and a much more ovate aperture. Furthermore, the spiral ridges in B. thermophilum is generally much sparser.
Provocator mirabilis (Finlay, 1926) <br /> VOLUTIDAE<br /> Dredged from deep water, New Zealand, 122.4mm <br /> <br /> The "Astonishing Volute" or the "Golden Volute" is an elegant deep water volute endemic to sub-Antarctic Pacific waters around New Zealand. It is a locally not uncommon predatory gastropod living on muddy bottoms and has a rather wide bathymetric range between approximately -200~1500m. Unlike other members of genus Provocator it has a rather thick shell and no columellar folds, and is thus often placed in its own genus Iredalina. The protoconch is usually glazed over and forms a posterior spike-like structure, which varies in length and is rarely preserved completely. Two forms seem to exist: a more common form with sloped spire and more stout shell; and a rarer form with stepped spire and elongated shell (shown). Colour uniform, varying from pale to rather dark orange; a scarce white form occurs off Auckland Islands. Adults have thickened lip and the average shell length is about 100mm, but giants exceeding 160mm (with long, well preserved spike) are known to exist.
Buccinum mizutanii Habe & Ito, 1970 <br /> BUCCINIDAE<br /> -80m, Dredged, Off Kuril Islands, 1991, 77.5mm <br /> <br /> The "Mizutani's Whelk" is a uniquely sculptured cold-water buccinid ranging from Hokkaido, Japan to the Sea of Okhotsk. Whorls carry two prominent, thick spiral cords on the body whorl an additional weaker one on the base. The first cord below the shoulder is usually the strongest and is characteristically nodulose, giving it an unmistakable strongly wavy appearance. It is most similar perhaps to B. nodocostum Tiba, 1984, which shares the nodulose spiral cord but differs by the cords being more numerous and much narrower as well as less prominent. Buccinum opisoplectum Dall, 1907 and B. glaciale f. inclitum Pilsbry, 1904 are also similar but likewise these species also have more numerous, much narrower spiral cords and are easily separable. It appears to be a very rare species in the shell trade market. A carnivorous and scavenging gastropod, it inhabits muddy bottoms of rather deep water around -100~500m. Typical shell length around 90mm, very large specimens may reach 120mm. It is named in honour of Mr. Shosan Mizutani, a fisherman based in Abashiri, Hokkaido who first discovered this species.
2016年の一貝目は今年の干支「申」にちなんで、サルアワビ！この仲間は軟体が猿の尻のように赤いことから名付けられました。<br /> <br /> 2016 is upon us, and it is a year of Monkey. The genus Scelidotoma is known as "Monkey Abalone" (saru-awabi) in Japanese as their soft parts are red, just like the bottoms of monkeys. Here's one from Japan to celebrate the arrival of a Monkey year! <br /> <br /> Scelidotoma gigas (Martens, 1881)<br /> FISSURELLIDAE<br /> -20~25m, Coast of Yagi, Hirono-cho, Iwate Prefecture, Japan, 82.3mm, F++, 2014/vii<br /> <br /> The "Giant Tugali Limpet" is a very large fissurellid native to northwest Pacific, with a distribution ranging from northern Korea and Japan (north of Fukushima Prefecture) to Sakhalin. A rather uncommon algae-grazing herbivorous species, it inhabits hard rocky substrates of intertidal to shallow subtidal waters down to about -30m deep. Although the shell is not colourful, its soft parts are vivid and brightly coloured in orange to red and the foot is larger than the shell. A shallow notch in the anterior end of the shell proves that it is a slit limpet, but this feature is often very inconspicuous in gerontic specimens. Typical shell length around 70mm, very large specimens may exceed 95mm. It used to be placed in the genus Tugali (hence the common name), but is now moved to Scelidotoma. Although the external appearance is similar to abalones, its flesh is said to taste bitter and vile when raw and tasteless when cooked. It is one of the host species of the symbiotic scale worm (Polychaeta: Polynoidae) Arctonoe vittata (Grube, 1855), which lives in the pallial groove of the host. The host helps the worm move about and protects it from predators, the worm does not feed on the host and in return helps the host fight off predators such as sea stars by biting them.
Thermosipho desbruyeresi (Okutani & Ohta, 1993) f. nipponensis (Okutani & Fujiwara, 2000)<br /> BUCCINIDAE<br /> -1002m, Iheya North Hydrothermal Field, Okinawa Trough, Japan, 80.2mm <br /> <br /> Thermosipho desbruyeresi is a large buccinid endemic to deep-sea hydrothermal vent fields. It has a wide distribution across Japanese vent sites in Okinawa Trough and Izu-Ogasawara Arc (depth range -600~1400m) and extending more than 8000km to Mariana, North Fiji and Lau Basins (depth range -1750~2750m). The Japanese population was described as a separate subspecies, T. d. nipponensis (Okutani & Fujiwara, 2000), but was later synonymised with T. d. desbruyeresi by Kantor et al (2013). A carnivorous / scavenging species, it has rather low population density and only rarely encountered especially in Okinawa Trough but is much more numerous in other localities. It is usually found on rock surfaces as well as in association with Bathymodiolus mussels which they feed on. The apex is always corroded away by the acidic flow of hydrothermal fluid, although the extent varies by locality and the acidity in the individual's microhabitat. The periostracum is often overlaid with various sulfide deposits from the vents, the extremeness of its habitat is evident. By far the largest gastropod native to Okinawa Trough hot vents, the average shell length is 70~80mm but giants may reach 100mm. It was originally described in the genus Eosipho, then considered to be an Enigmaticolus for a short period of time before the new genus Thermosipho was erected.
Bullia othaeitensis (Bruguière, 1789) <br /> NASSARIIDAE<br /> Masirah Island, Oman, 49.1mm <br /> <br /> Bullia othaeitensis is a very handsome nassariid characterised by numerous equally spaced spiral ridges. Native to Eastern Arabia with most specimens originating from Oman, the actual range may extend as far as Karachi, Pakistan. Its name is very confusing as although it is an arabian species, the specific epithet means "from Othaeite" with Othaeite being an alternative spelling of "Otaheite", an old name for Tahiti, French Polynesia. This is due to a mistake in recognising the origin of the type material, which unfortunately was not too uncommon back in the days when the accurate provinance for many species remained unclear for decades. In fact, the entire genus Bullia is absent from the Western Pacific. It is perhaps better known by the name Bullia tahitense (Gmelin, 1791) which is a junior synonym, and that name also means "from Tahiti". The two authors may have received material from the same lot with the same mistaken locality labels, especially considering the short time difference between the two descriptions, though this is merely speculation. The specific epithet is often misspelt in various ways, such as "otaheitensis" or "othaeitense". It is a very rarely available speices, mostly absent from collections. Fresh specimens carry sparse orange-brown axial flammules, though these fade over time. A carnivorous and scavenging gastropod, it inhabits sandy bottoms of shallow waters down to about -15m. Typical shell length around 30mm, very large specimens as shown may exceed 45mm.
Harpa doris Röding, 1798 <br /> HARPIDAE<br /> -2.5m (-8 ft), Dived by local person, On clean brown sand, Off Dakar, Senegal, 65.6mm <br /> <br /> The "Rosy Harp" is a lovely harpid ranging from Senegal to Angola, and is the only recent Harpa species in the Atlantic Ocean. It is characterised by radial bands of rectangular, rosy red patches that makes it an especially beautiful harp shell. The extent of red patches vary greatly among individuals and the synonym H. rosea Lamarck, 1816 is often used as a form name by collectors and dealers for exceptionally reddish specimens. Two distinct forms are known, the nominal form from coastal mainland Africa (shown) has thin, lightly constructed and more slender shells; whereas the form from Ascension Island and Cape Verde Islands are much more robust and shorter. The island form was initially described as a separate species, H. robusta Röding, 1798, and although regarded as a synonym today many feel it is still worthy of a subspecific rank if not a full species. Like all Harpa species it is a carnivorous and predatory gastropod that mainly feeds on small crustaceans, and inhabit shallow sandy bottoms to -30m depth. Typical shell length for the nominal form around 60mm, very large specimens may exceed 80mm; the island form is generally smaller and averages at around 40mm, though the largest specimens may exceed 70mm. It used to be a rarity before around 1980s when the Atlantic shells were less readily available, today it is regarded as a common species and has become easily obtainable.
Cardiomya behringensis (Leche, 1883) <br /> CUSPIDARIIDAE<br /> -350m, In shrimp traps, Off Teuri Island, Hokkaido, Japan, 2000/xi, 38.1mm <br /> <br /> Cardiomya behringensis is a rather solid medium-sized cuspidariid ranging from Honshu, Japan (both Pacific and Japan Sea) to Sea of Okhotsk to as far north as Bering Sea. Being a cuspidariid it is a carnivorous and predatory bivalve which hunts small animals, mostly crustaceans such as copepods and ostracods, using the inhalent siphon's suction power. It inhabits muddy bottoms of deep water around -200~450m deep, and is always covered by a layer of mud on top of the periostracum in natural condition. A very rare species, it is a celebrated collector's item among those who collect cuspidariid clams and difficult to acquire in collectible condition. Typical shell length around 20mm, very large specimens such as the one depicted may reach and exceed even 40mm.
Cuspidaria trosaetes Dall, 1925 <br /> CUSPIDARIIDAE<br /> -350m, In shrimp traps, Off Teuri Island, Hokkaido, Japan, 2000/xi, 28.5mm <br /> <br /> Cuspidaria trosaetes is a delicate, medium-sized cuspidariid from the Japan Sea, ranging from Hyōgo Prefecture to Hokkaido, Japan (and maybe the Kuril Islands). Like other members of Cuspidaria, it is a truly carnivorous and predatory bivalve that actively hunts small crustaceans (such as copepods and ostracods) using its inhalent siphon and trapping them in the mantle cavity. It inhabits a rather wide bathymetric range of around -50~650m, and is usually found on soft bottoms. It is characterised by a short, compressed posterior rostrum and a well inflated oval shell. The shell itself is white, with a greenish-brown periostracum which is thin and semi-transparent at first but increasingly thickens and as a result becomes more opaque in later stages. A rare species, it is very difficult to obtain a live-taken specimen in good condition. Typical shell length around 30mm, very large specimens may exceed 40mm.
Maurea tigris (Gmelin, 1791)<br /> CALLIOSTOMATIDAE<br /> New Zealand, 1960s, 62.0mm <br /> <br /> Delicately painted with alternating chestnut and pale yellow stripes, the "Tiger Maurea" is a beautiful endemic calliostomatid of New Zealand. It is the largest extant calliostomatid known to date, with the largest specimens reaching an impressive shell height of over 100mm, although vast majority are smaller and average at around 60mm. The largest specimens originate from off Three Kings Islands. The surface sculpture is fairly consistent, although the spire form varies from narrow conical to broad conical. The early whorls are almost always characteristically narrow and differ in sculpture from later whorls. Fully mature specimens have the inside of the outer lip noticeably thickened. The colouration pattern can vary quite a bit, for example many from off the Chatham Islands lack discrete axial bands with more scattered pattern, which was named as a subspecies C. tigris chathamensis (Dell, 1950) but now considered to be a synonym. It is a carnivorous grazer feeding on thecate hydroids and occur on rocky substrates from very shallow intertidal waters down to rather deep water around -200m. It is usually placed in the subgenus Maurea, which many consider worthy of a full genus rank.
Neancistrolepis glabra Habe & Ito, 1973 <br /> BUCCINIDAE<br /> -550~560m, 44°09.9'N 144°33.0'E, By deep-water whelk pot, Off Abashiri, Hokkaido, Japan, 1996/vii, 126.8mm <br /> <br /> Neancistrolepis glabra is a cold-water whelk with smooth, glossy periostracum ranging from Hokkaido, Japan to the Okhotsk Sea. A carnivorous and often scavenging gastropod, it inhabits sandy to muddy bottoms of deep water around -500~800m. A highly coveted species by collectors of Buccinidae, it is an extremely rare species on the international shell trade, especially adult specimens of decent quality. Even locally in Japan it is now quite a rarity, it was once only uncommon but now the supplies have effectively run dry. In fully adult specimens, the outer lip recurves slightly and characteristically flares out, extending anteriorly. The periostracum is often darker coloured in adults than juveniles and peels off rather easily when dried. The operculum is teardrop shaped and as usual for the genus Neancistrolepis it is much smaller than the aperture, though not as small as in the genus Parancistrolepis. Typical shell length around 110mm, very large specimens may exceed 140mm. It is one of only two currently recognised species in the genus Neancistrolepis, the other being N. beringianus (Dall, 1919).
Bolma johnstoni (Odhner, 1923) <br /> TURBINIDAE<br /> -90~120m, Trawled, Off N'zeto (aka. Ambrizete), Zaire, Angola, 48.4mm <br /> <br /> Bolma johnstoni is a stunning turbinid characterised by a well-developed, near-black basal callous which makes it unforgettable and unmistakeable. The shell surface carry scaly sculpture and a single row of rather long spines, the operculum is an attractive reddish-brown coloured one with a granulose central area. A famous endemic species of Angola, it is a rare species due to its restricted distribution and is much sought-after by collectors. It inhabits rather deep water around -70~120m, and although no reliable data exists regarding its detailed feeding behaviours it is almost certainly a grazer. Typical shell diameter including spines around 40mm, very large specimens may exceed 50mm. In the original description it was placed in the genus Astraea, and later moved to Bolma, its current genus. On dealers' lists and collection databases it is quite often misspelt as "Bolma johnsoni" (missing a "t" in the specific epithet).
Perotrochus pseudogranulosus Anseeuw, Puillandre, Utge & Bouchet, 2015 <br /> PLEUROTOMARIIDAE<br /> -300m, Trawled, Off Nouméa, New Caledonia, 2011, 41.0mm <br /> <br /> Perotrochus pseudogranulosus is a recently described medium-sized slit shell, previously confused with P. caledonicus Bouchet & Métivier, 1982. Due to the well-known existence of a "smooth" and a "pustulose" form with apparently no intergrades, there has been a long suspicion that Perotrochus species from around New Caledonia, previously all attributed to P. caledonicus, might actually be a species complex of at least two species. Indeed, an investigation using both morphology and molecular sequencing of the COI barcoding gene revealed in 2015 that the two were distinct species. The "smooth" form with unbeaded to weakly beaded spiral ribs but lacking in significant pustulation matches the type series of P. caledonicus, whereas the "pustulose" form with strongly beaded ribs is a separate species described as P. wareni Anseeuw, Puillandre, Utge & Bouchet, 2015. Surprisingly however, a further previously undescribed species was detected from the Coral Sea material -- P. pseudogranulosus. Perotrochus pseudogranulosus is rather similar to P. caledonicus but can be distinguished by a more conical shell with much more flattened basal disc, the presence of a characteristic strong metallic lustre on the shell surface, and a more regular "checkerboard" pattern under the selenizone. The spiral cords tend to be finely beaded, especially above the selenizone, hence the specific epithet. Phylogenetic reconstructions using the COI gene suggest it is in fact most closely related not to P. caledonicus but to P. deforgesi Métivier, 1990, which is sister to the P. caledonicus -- P. wareni group. The original description was based only from materials collected from the Coral Sea and restricted to the Chesterfield Plateau; but seeing a number of specimens has turned up in the shell trade throughout the past years with the locality data near New Caledonia, its true distribution may extend to as far as western New Caledonia. Presumably a carnivorous grazer feeding mostly off sponges like other pleurotomariids, it inhabits rather deep water around -300~500m deep. Typical shell diameter around 40mm, extremely large specimens may exceed 55mm. This species appears to be rare in the shell trade market, much rarer than either P. caledonicus or P. wareni, most likely due to its main habitat in the Coral Sea is too remote for regular visits to be made.
Neptunea nivea Okutani, 1981<br /> BUCCINIDAE<br /> -1300m, Cape Erimo, Off Shoya, Horoizumi District, Hokkaido, Japan, 2010/x, 104.4mm <br /> <br /> Despite its plain appearance, Neptunea nivea is a cold-water whelk most sought-after by collectors of the family Buccinidae, especially in Japan. This is because it is a bathyal species inhabiting very deep water around -1000~3000m, and as a result it very rarely appears on the market. A carnivorous and scavenging gastropod inhabiting soft muddy bottoms, it is supposedly endemic to a small part of Pacific Japan ranging from Miyagi Prefecture to southern Hokkaido, although its true range may extend to the Sea of Okhotsk. Most specimens have been obtained as trawl by-catches from either off Kinkasan, Miyagi Prefecture or Cape Erimo, Hokkaido. The shell is ornamented by indistinct spiral ridges which is weakest on the body whorl, and bear a thin layer of greenish brown periostracum which is usually almost completely eroded away in adult specimens. The apex is usually corroded to a certain extent; the operculum is smaller than the aperture although a certain variation is seen in its size relative to the aperture. Typical shell length around 100mm, extremely large specimens may exceed 140mm. It may be confused with Neptunea convexa Goryachev, 1978, but differs from it by having a more inflated shell, deeper suture, and relatively shorter spire. It has been placed by some authors, such as Higuchi, 2006, in the genus Tacita; but it is currently generally accepted to be a member of Neptunea.
Buccinum lamelliferum Lus, 1976 sensu Higuchi, 2006<br /> BUCCINIDAE<br /> -1300m, Trawled, Off Kinkazan, Miyagi Prefecture, Japan, 2006/vi, 99.0mm <br /> <br /> The true identity of this dignified, graceful, and spectacularly sculptured whelk has been much debated. This shell is characterised by three very strong, erected spiral keels (the third is below the suture line and may be very weak) and inhabit soft bottoms of great bathyal depths between -1000~3000m. It is an extremely rare shell especially in collectible condition, partly due to the great depths it dwells in; it is much sought-after among Japanese collectors. Vast majority of specimens have been collected off Miyagi Prefecture, Japan. The Japanese collector Shigeo Higuchi beautifully showed six specimens in his major publication "Northern Shells" (2006, Plate 107-108, "Higuchi shells" hereafter) and referred them to the name Buccinum lamelliferum Lus, 1976 after the specimen illustrated (Fig. 209, p. 498) in Prof. Takashi Okutani's "Marine Mollusks in Japan" (2001). There is a very similar species, Buccinum kashimanum Okutani, 1964, which is known to show vast variation between having no spiral keels and having as many as five spiral keels; but Higuchi deemed his specimens differed from B. kashimanum by the lack of conspicuous spiral threads which characterises B. kashimanum. This was true for Higuchi's specimens which only had very fine and discreet striations (as illustrated here). Interestingly however, the specimen in the Okutani book that Higuchi compared with actually has noticeable spiral threads like B. kashimanum and is thus probably actually a variation of that species. Furthermore, it was realised that the holotype of B. kashimanum has a similar sculpture with two storng keels and only very weak spiral striations. A comparison with the holotype of B. lamelliferum also reveals that the holotype actually has four spiral keels and appear quite different from the Higuchi shells (although some of the B. lamelliferum paratypes did have three keels their positions differed). Whether the true B. lamelliferum is actually also a synonym of B. kashimanum is an interesting question but fresh specimens from the type locality (off Kuril Islands) is required to shed further lights on this matter. The distribution range of the true B. lamelliferum is probably only north of Hokkaido, Japan to Kuril Islands; whereas the range of B. kashimanum is from Kashima-nada, Ibaragi Prefecture to Hokkaido, Japan. It therefore appears that the Higuchi shells is most likely not B. lamelliferum but either an extreme variation of B. kashimanum or an undescribed species; recent publications such as Hasegawa, 2009 and Higuchi, 2014 have adopted the former explanation and refer to the Higuchi shells as B. kashimanum VAR. Nevertheless, in the shell trade market (especially locally in Japan), the name B. lamelliferum still refer to this form (i.e., the Higuchi shell) and this is unlikely to change for sometime as this form is much rarer and fetch much higher prices than standard B. kashimanum (which is only somewhat uncommon in good condition). Typical shell length around 90mm, extremely large specimens may exceed 110mm.
Leptoconus kawamurai (Habe, 1962) <br /> CONIDAE<br /> Naze, Amami Ōshima, Kagoshima Prefecture, Japan, 1989/vii, 51.4mm <br /> <br /> The "Kawamura's Cone" is an elegant Western Pacific conid with a relatively tall spire and tent-like pattern. Although it is widely accepted to distribute in the Ryukyu Islands from the Amami Islands (type locality) to southern Okinawa, morphologically similar specimens have been taken from Taiwan and even as far as Guam. Vast majority of specimens are dead-collected from sands pumped up from a few dozen metres deep for making beaches and harbour works in Okinawa, such specimens are uncommon. Live specimens are extremely rare and it was once even believed to be an extinct species, but the first live specimen was obtained in 1989 from Naze, Amami Ōshima Island, followed by a few more. A carnivorous and predatory gastropod probably feeding mostly on other molluscs, it inhabits rather shallow waters up to 50m deep. It is a There is a long debate about whether it is a geographic subspecies/form of Leptoconus milneedwardsi (Jousseaume, 1894) or a separate species, although in the recent years it is generally treated as a full species in its own right. It differs from L. milneedwardsi by the consistently much smaller size (up to 100 mm vs up to 180 mm in shell length) and a much shorter spire. Typical shell length around 70mm, extrmely large specimens may exceed 90mm.
Cymbiola perplicata (Hedley, 1902) <br /> VOLUTIDAE<br /> Lihou Reef, Coral Sea, Off Queensland, Australia, 1995/xii, 73.0mm <br /> <br /> The "Entangled Volute" is a delightful volute characterised by stunning golden axial lines, and is a much sought-after rarity among the volutes. The original description was based on three poor beached shells from Australian fishermen, but with no further specimens being found its true provenance remained a mystery. That is, until its re-discovery in the late 1970s by Mr. Tom Nielson of Yeppoon, Queensland, Australia and his team. Nielson had already re-discovered other rare shells, including another rare volute Cymbiola thatcheri (McCoy, 1868), using special shell dredges in the early 1970s on-board the chartered boat "Coralita". His early searches for C. perplicata funded by Mr. John du Pont had ended in no avail, however; and it was only after repeated cruises (also on-board the "Coralita") that he finally managed to locate and collect live specimens of C. perplicata in the Coral Sea. His early expeditions were recorded in a film entitled "In Search of the Perplicata", though virtually no remaining copies of it appear to exist. Today it is known to be an endemic of the Australian Coral Sea, and remains rather scarce still. A carnivorous gastropod like all volutes, it inhabits sandy bottoms of shallow to moderate depths around -2~40m. Typical shell length around 65mm, extremely large specimens may exceed 90mm.
Morum dennisoni (Reeve, 1842) <br /> HARPIDAE<br /> -200~250m, Trawled, Cuba, 2000/x, 52.0mm <br /> <br /> A truly magnificent orange-red parietal shield ornamented with white pustulation makes "Dennison's Morum" one of the most beautiful Moruminae species. A classic Carribean rarity first described from John Dennison's cabinet, it was selected as one of S. Peter Dance's 50 "Rare Shells" (1969) and was virtually unobtainable until the late 20th century. Somewhat variable in size, colouration, extent of shield pustulation, and strength of shoulder spines. The general form varies also according to size, with larger specimens becoming more elongated with weaker shoulder spines. A carnivorous and scavenging gastropod inhabiting sandy to muddy bottoms, it is usually found in rather deep water around -50~200m deep. Its geographic range is quite wide, from North Carolina, USA to as far south as Brazil. Most specimens are caught as by-catches of shrimp trawlers. Today it is still somewhat rare, and due to the high demand large specimens in good condition continue to fetch considerable prices. Typical shell length around 45mm, extremely large specimens may exceed 65mm.
Hysteroconcha lupanaria (Lesson, 1831)<br /> VENERIDAE<br /> Guaymas, Mexico, 1968/x, 78.2mm<br /> <br /> The "Panamic Comb Venus" is an immediate standout among bivalves with two rows of long spines protruding from the posterior slope of each valve as it is very unusual for a non-spondylid bivalve to have long spines. Younger specimens tends to have longer, more intact spines; large specimens usually have most spines broken off. It is a locally common burrowing filter feeder living on sandy bottoms from intertidal to -5m depth, but due to its limited distribution specimens are uncommon on the shell trade market. Large specimens with good spines, especially, are quite rarely seen. In life it is buried with its long spines positioned upwards, possibly used as a defence against predators. Distributed in the Eastern Pacific Ocean from Mexico to Peru, it is very similar to its congeners H. dione (Linnaeus, 1758) and H. multispinosa (Sowerby II, 1851). Hysteroconcha dione tends to have shorter spines and is distrubuted only in the Western Atlantic Ocean, whereas H. multispinosa is also an Eastern Pacific species but has more prominent, erect ribs and more numerous spines. Typical shell length without spines about 40mm, extremely large specimens may exceed 65mm and length including spines may exceed 90mm. It has long been placed in the genus Pitar, and is still often seen listed under that genus.
Tropidophora deburghiae (Reeve, 1861) <br /> POMATIIDAE<br /> High in tree tops, About 50km into mountainous primary forest accessible only by muddy trail, 40+ km north of Mananara on road to Maroantsetra, Coastal northeast Madagascar, 2000/x, 47.9mm <br /> <br /> A truly eccentric combination of shape and pattern makes "Mrs. de Burgh's Torpid" one of the most outstanding and famous out of many landsnail species endemic to the great island of Madagascar. It is endemic to northeastern Madagascar, living deep in rainforest and high on tree tops, making it a difficult species to collect. An assessment by the IUCN in 1996 concluded that it was an endangered species and although it is still considered rare and endangered today, little further information have become available to provide a reliable update on the current status of its population. The shell form is little-varied although the pattern vary slightly among specimens. It is often seen listed under the family Pomatiasidae, but Pomatiasidae is currently considered to be a junior synonym of Pomatiidae. Although a landsnail, its chalky operculum reveals its systematic position in the superfamily Littorinoidea, meaning it is in fact a close relative of periwinkles which have managed to invade the terrestrial ecosystem. Typical shell diameter around 45mm, very large specimens may exceed 55mm.
Perotrochus vicdani Kosuge, 1980 <br /> PLEUROTOMARIIDAE<br /> -200~250m, Balut Island, Davao Occidental, Mindanao, Philippines, 2008/x, 56.0mm <br /> <br /> The "Victor Dan's Slit Shell" is a vibrant light-weight Western Pacific pleurotomariid ranging from the Philippines to Vietnam, although vast majority of specimens known originate from the Philippines. It was the first extant slit shell species to be discovered in the Philippines, being described ten years earlier than Mikadotrochus gotoi (Anseeuw, 1990). The form is quite variable in terms of spire height and steppedness, and so is the colouration in terms of strength of redness as well as the amount of flammules. Specimens from the area between Balicasag and Siquijor tends to have more intense red colour than usual. A carnivorous grazer feeding mostly on sponges, it inhabits rather deep water around -100~400m in depth. Typical shell diameter around 50mm, extremely large examples are known to exceed 70mm. Although it used to be a very rare species in the past, thanks to deep-water tangle nets smaller sized specimens are only uncommon nowadays, although large specimens over 55mm in shell diameter remains scarce. It is named in honour of Mr. Victor Dan, a famous shell enthusiast, collector, and dealer based in the Philippines.
Bayerotrochus africanus (Tomlin, 1948) <br /> PLEUROTOMARIIDAE<br /> -300m, Trawled, Off Durban, Natal, South Africa, 1986/x, 116.7mm <br /> <br /> The "African Slit Shell" is a large, light weight pleurotomariid native to eastern and southern Africa, ranging from around Mozambique to South Africa. Most specimens originate as trawl by-catch off South Africa, and it appears to be an uncommon species. It is quite variable in colouration of the flammules, ranging from pale to deep red. A carnivorous grazer feeding mostly on sponges like other slit shells, it inhabits sandy to muddy bottoms of rather deep water around -150~400m in depth. It is quite similar to its common congener B. teramachii (Kuroda, 1955) found in the western Pacific, but has a more strongly stepped spire and its spiral striations are much less beaded compared to B. teramachii. The shell therefore typically appear broader and smoother with higher gloss than B. teramachii. Although B. teramachii has been considered to be its subspecies in the past, both are currently recognised as separate species in their own right. Typical shell diameter around 110mm, though very large specimens may exceed 130mm.
Bayerotrochus teramachii (Kuroda, 1955) <br /> PLEUROTOMARIIDAE<br /> -200~250m, Trawled, Off Makurazaki, Kagoshima Prefecture, Japan, 2010/vi, 90.6mm <br /> <br /> The "Teramachi's Slit Shell" is a brilliantly lustrous pleurotomariid ranging from Honshu, Japan to Taiwan to South China Sea. It is characterised by the golden surface with a metallic sheen, as well as numerous fine but strongly and regularly beaded spiral lirae. The delicately beaded sculpture is more or less consistent among specimens. The shell form, on the contrary, is quite variable especially the spire profile. It was previously considered a Western Pacific subspecies of Bayerotrochus africanus (Tomlin, 1948) but today it is widely accepted as a full species in its own right. Indeed, it is rather similar to many Indo-Pacific Bayerotrochus species including B. africanus but also others such as B. westralis (Whitehead, 1987) and B. philpoppei Anseeuw, Poppe & Goto, 2006; these may form a species complex but genetic data required for further insights is currently lacking. Once a rare species and commanded high prices but since deep-water trawlers in Japan and Taiwan started bringing large quantities to surface its price has plummeted, even more so after the Chinese trawlers started doing the same. It is now the second most common pleurotomariid on the shell trade market, after Mikadotrochus hirasei (Pilsbry, 1903). A carnivorous grazer feeding mostly on sponges, it inhabits sandy bottoms of rather deep water around -200~600m. Typical shell diameter around 100mm, extremely large specimens may exceed 140mm. Its name honours the late Mr. Akibumi Teramachi, who is widely accepted as the greatest Japanese collector of the time. Teramachi was a painter who lived in Kyoto, and after he passed away his collection was bequeathed to Toba Aquarium on the condition of permanent storage. This included the holotype specimen of B. teramachi, which still resides in the Toba Aquarium Collection today. Since then Toba Aquarium has become famous for its affliation with shell collecting and continues to have a shell dealer department today.
Lyncina kuroharai (Kuroda & Habe, 1961) <br /> CYPRAEIDAE<br /> -150m, Trawled, Okinoshima, Munakata, Fukuoka Prefecture, Japan, 1980/vii, 40.1mm <br /> <br /> The "Kurohara's Cowrie" is a lovely medium-sized cypraeid ranging from Honshu, Japan to East China Sea to Taiwan. A classic rarity among Western Pacific cowries, it can be safely separated from other superficially similar Lyncina species such as L. schilderorum Iredale, 1939 and L. sulcidentata (Gray, 1824) by its very fine teeth, curved aperture, and inflated shape. It is a omnivorous grazer living among sponges and rubbles, usually in relatively deep water around -50~250m, although it is occasionally found as shallow as -10m. Very rarely such specimens are washed up on the beach, becoming a rare trophy of beachcombers. Though in recent years Chinese trawlers have brought up numerous specimens from the East China Sea making it much easier to acquire, it is very prone to imperfections such as growth scars and octopus holes and perfect specimens are still very scarce today. Typical shell length around 40mm, extremely large specimens are known to exceed 60mm. It is named in honour of Kazuo Kurohara of Japan.
Mikadotrochus beyrichii (Hilgendorf, 1877) <br /> PLEUROTOMARIIDAE<br /> -100~120m, Trawled, Off Mimase, Kōchi, Kōchi Prefecture, Japan, 1969/vi, 84.4mm <br /> <br /> The "Beyrich's Slit Shell" is a striking pleurotomariid endemic to Japanese waters, best known from the central portion of Honshu Island. Although the third to be formally described it is actually the earliest living slit shell recorded and illustrated in the recent literature, being included in Japanese books such as "Kigai-zufu" (Kenkado Kimura, 1775) and "Mokuhachi-fu" (Sekiju Musashi, 1843) long before Perotrochus quoyanus (Fischer & Bernardi, 1856) was discovered in the Caribbean Sea. These Japanese books were unknown to scientists outside the country then, however. This species was thus overlooked until Franz Martin Hilgendorf (1839-1904), a German zoologist, found a specimen in a souvenir shop of Enoshima, Kanagawa Prefecture, Japan in 1876. He described it the following year, naming it after Heinrich Ernst Beyrich (1815-1896), a famous German palaeontologist who first proposed the term 'Oligocene'. It has traditionally been a greatly celebrated rarity, especially among Japanese collectors, and remains scarce nowadays. After Hilgendorf reported its existence the British Museum (Natural History) in London commissioned the University of Tokyo to find a specimen. It was the eminent professional marine animal gatherer Kumakichi Aoki (1864-1940), working for the Misaki Marine Station, who successfully collected a living specimen in the following spring. He was rewarded with the prize of 40 Japanese yen, a huge sum back then. Upon receiving the prize Aoki supposedly exclaimed "I've become a millionaire!", which leads to this species being sometimes called "Cho-ja-gai" (Millionaire Shell) in Japan, even today. A carnivorous grazer feeding on sponges, it usualy inhabits rocky bottoms around 100~300m deep but has been found as shallow was -30m, making it the shallowest living of all recent pleurotomariids. Strong, broad radial lirae on the shell surface are crossed by relatively infrequent axial ribs to generate the characteristic coarsely chequered sculpture. The frequency and extent of red flammules vary according to localities, with specimens from Chiba Prefecture and Tokyo Bay having the darkest colouration. The shell form also vary somewhat by locality, for example shells from Kōchi Prefecture (shown) are usually broader than typical specimens from Chiba Prefecture. Typical shell length around 70mm, very large specimens may exceed 100mm.
Perotrochus atlanticus Rios & Matthews, 1968 <br /> PLEUROTOMARIIDAE<br /> -200~250m, Trawled, Off Cabo de São Tomé, Rio de Janeiro, Brazil, 1998/x, 62.5mm <br /> <br /> The "Atlantic Slit Shell" is a gorgeous medium-sized pleurotomatiid endemic to southern Brazil, from around Rio de Janeiro to as far south as the Brazil-Uruguay border. The shell is heavily ornamented by finely beaded coarse spiral cords and numerous flammules, the colouration of which vary from red to brown and the saturation vary from one specimen to another. The characteristic shape of adult shells is formed by the gradual shifr of the whorls being smooth-sided, as in the early teleoconch, to strongly inflated and bulging ones in the later stages. It is locally only uncommon and is perhaps the most easily obtainable Atlantic slit shell, although it is very susceptible to erosion and bore-holes, specimens in fine conditon are thus still considerably rare. A carnivorous grazer feeding on sponges, it inhabits sandy to muddy bottoms of rather deep water around -150~300m. Typical shell diameter around 65mm, extremely large specimens are known to exceed 85mm. The spire is variable in height although usually it is usually low; the name Perotrochus notialis (Leme & Penna, 1969) refers to a high-spired form and is now considered to be a junior synonym.
Halicardia nipponensis Okutani, 1957 <br /> VERTICORDIIDAE<br /> -500~600m, Trawled, Off Sōma, Hamadōri, Fukushima Prefecture, Japan, 2006/viii, 32.0mm <br /> <br /> The exceptionally exquisite Halicardia nipponensis, with its unique shape formed by two strong radial ridges, is certainly one of the most unusual bivalves of all. It is a carnivorous bivalve inhabiting muddy bottoms of deep-water ranging from -500~1500m, and feeds on small invertebrates such as copepods by capturing them using mucus-lined tentacles. It is a renowned endemic of Japan only found off the northern half of the Pacific Honshu. An incredibly coveted species, especially in Japan where its beauty is greatly celebrated, it is only very rarely obtained by deep-water trawling and command high prices. When seen from the anterior view its shape resembles two hearts, the interior also carry heart-shaped hinge tooth. Futhermore, its side views are strongly reminiscent of the kanji (Chinese character) for "heart". It is therefore known in Japan as the "Nippon-otohime-gokoro" (literally, "Heart of the Japanese Maiden Princess"), aptly named by Prof. Takashi Okutani. This brilliant wamei (Japanese name) is part of the reason why it is an especially popular shell in Japan. Although its congener Halicardia maoria Dell, 1978 from New Zealand is tentatively reported to be associated with deep-sea hydrocarbon seeps, it is unclear whether H. nipponensis does the same. Typical shell length around 32mm, extremely large specimens are known to exceed 40mm.
Perotrochus quoyanus (Fischer & Bernardi, 1856) <br /> PLEUROTOMARIIDAE<br /> -200~210m, Collected by submersible, Off Sandy Lane Bay, Barbados, 1998/vi, 52.4mm<br /> <br /> First discovered by Commandant Beau in the Marie-Galante Island, Guadeloupe in 1855, the legendary "Quoy's Slit Shell" was the first living pleurotomariid species formally exposed to science. The encounter of this species is among one of the most important landmarks in malacology and generated great excitement, as previously this important ancestral lineage of basal gastropods were considered long extinct; the finding of living species opened up wholly new possibilities in studying the evolution of gastropods. It was therefore selected as one of S. Peter Dance's 50 "Rare Shells" (1969). The first specimen (i.e., the holotype) was taken from a fisherman's pot set in deep-water, and it was inhabited by a hermit crab. This was closely followed by the exposure of Entemnotrochus adansonianus (Crosse & Fischer, 1861) and Mikadotrochus beyrichii (Hilgendorf, 1877), up until now some 30 living pleurotomariid species have been described. In fact, M. beyrichii was illustrated in the Japanese books such as "Kigai-zufu" (Kenkado Kimura, 1775) and "Mokuhachi-fu" (Sekiju Musashi, 1843) long before the detection of P. quoyanus, but these books was not known to scientists in the western world then. Today, P. quoyanus is known to have a rather wide distribution around the Caribbean Sea from Yucatan, Mexico to Virgin Islands to Venezuela. Furthermore there is one recognised subspecies, P. quoyanus insularis Okutani & Goto, 1985, described from the Bermuda Islands and has a much taller spire with more swollen whorls. Specimens with a similar form has since been found as far as Honduras, however. The name Perotrochus gemma Bayer, 1965 was previously considered to be a separate species but is now regarded as a gemmate form of P. quoyanus and thus a junior synonym of it. The shell is therefore rather variable in spire height and strength of surface sculpture (i.e., 'gemmation'), the colouration is also variable from rather pale to strongly flamed with reddish axial bands. It is a carnivorous grazer feeding mostly on sponges and usually inhabit hard substrates in deep water around -180~350m. Due to its deep habitat it is still a rare shell, especially live-collected in fine conditon; such shells are virtually only obtainable using deep-water submersibles as trawls rarely operate near the rocky walls it inhabit. Typical shell length around 45mm, extremely large specimens may exceed 60mm.
Mikadotrochus salmianus (Rolle, 1899) <br /> PLEUROTOMARIIDAE<br /> -240m, Trawled, Off Tosa, Kōchi Prefecture, Japan, 1967/vi, Ex-Coll. Helen Boswell, 116.2mm <br /> <br /> The "Salmiana Slit Shell" is an elegant pleurotomariid with a blazing coluration and a characteristically tall spire, ranging from Honshu, Japan to Taiwan to Philippines. A much sought-after rarity, most specimens have generally come from Taiwan although recently Chinese fishermen have also trawled many (mostly poor) specimens from the East China Sea. It reaches the largest size in Tosa Bay, Japan where the shells are the thickest and with a rather pale colouration; the shells gradually thins down towards south with specimens from the Philippines being the lightest in build but with a dark colouration. Both Tosa Bay and Philippines specimens are still very scarce today, especially in large size, though in the East China Sea it is probably best described as uncommon. A carnivorous grazer feeding on sponges, it inhabits hard substrates of rather deep water around -100~400m. Typical shell length around 90mm, extremely large specimens are known to exceed 135mm. For many decades since its description it was confused with its congener Mikadotrochus beyrichii (Hilgendorf, 1877) due to the small quantity and poor quality of available specimens. As better specimens surfaced, however, its obvious differences with M. beyrichii quicky became apparent and it has become widely accepted as a valid species since the 1970s. A well-known synonym is Mikadotrochus schmalzi Shikama, 1961.
Entemnotrochus adansonianus (Crosse & Fischer, 1861) <br /> PLEUROTOMARIIDAE<br /> -120~130m, Collected by submersible, Off Half Moon Bay, West End, Roatán Island, Bay Islands, Honduras, 2009/ix, 129.3mm <br /> <br /> The majestic and magnificently flamed "Adanson's Slit Shell" is perhaps one of the most beautiful pleurotomariids, and also a renowned and celebrated classic rarity among them. As the first of S. Peter Dance's 50 "Rare Shells" (1969) a photo of one of the oldest surviving specimens, purchased by Samuel Archer in Barbados in the 1800s, serves as the book's cover. A rather widely ranging species in the western Atlantic Ocean, it is best known from the West Indies and Caribbean Sea but the full geographical distribution ranges from as far as Bermuda down to Brazil. Specimens from Bermuda differs from all others in having a more vertically compressed shell of much smaller size (to 100mm), the spire also appears much more strongly stepped as the whorls are strongly shouldered. These Bermudian specimens are thus separated as a valid subspecies, E. adansonianus bermudensis Okutani & Goto, 1983. It is a carnivorous grazer feeding on sponges like the majority of pleurotomariids, and inhabits vertical rocky walls of rather deep water around 100~300m in depth. Even with all these knowledge about its ecology it is still a very rare shell on the international market nowadays because the steep rock walls it inhabit is well protected from traditional fishing methods. Dredging or trawling only uncover dead-taken or crabbed specimens, and traps have been effective in gathering only crabbed shells. Most live-taken specimens in fine quality, like the one shown, have therefore been carefully collected by underwater submersibles. The subspecies E. a. bermudensis is rarer still, with virtually no live taken examples so far known. The pattern is somewhat variable, although most specimens carry alternating red and pale patches. Large specimens tends to have less sharp, saturated colouration. Typical shell diameter around 110mm, although extremely large examples are known to reach a staggering size of 190mm. It is the second largest of all living slit shells, only surpassed by its Pacific congener E. rumphii (Schepman, 1879). Currently these two species are the only recognised valid species of the genus Entemnotrochus.
Kendrickiana veitchi (Smith, 1971) <br /> PENICILLIDAE<br /> Low tide, Broome, Kimberley, Western Australia, Australia, 203.1mm <br /> <br /> The "Veitch's Wateringpot" is a strange and wonderful penicillid endemic to Western Australia and Southern Australia, Australia; best known from the Great Australian Bight. It is a member of the bivalve superfamily Clavagelloidea, characterised by their remarkable behaviour of switching from growing the true shell to building a calcareous tube, called the adventitious tube. At the earliest stages of life after settlement it bears a normal bivalved shell, which is still attached to the outside of the adventitious tube and visible; although in this species it is largely incorporated into the tube. Uniquely among penicillids its adventitious tube is strongly bulbous at the "watering-pot" end, divided into hundreds of small tubes, and is not distinctively fringed like most other species. A filter-feeding species, it appears to be restricted to soft bottoms of seagrass beds (such as Posidonia sp.) and inhabit subtidal waters down to about 50m deep. In life it lives vertically buried with the "watering-pot" end down. Although probably only uncommon locally, it is rarely seen in the international shell trade market. Previously it has been placed in the genus Brechites and then Foegia, but after detailed anatomical investigation a new genus, Kendrickiana, was erected to house it; it is currently the only species placed in that genus. Typical length of the adventitious tube around 200mm, although very large specimens are known to exceed even 370mm.
Paramoria guntheri (Smith, 1886) <br /> VOLUTIDAE<br /> -21m (-70 ft), In sandy rubble, By diver, Thorny Passage, South Australia, Australia, 54.5mm <br /> <br /> The deliciously patterned "Gunther's Volute" is a celebrated classic rarity among the volutes, endemic to southern Australia. Initially only known from a handful of dead-collected specimens, a live specimen was first discovered in May 1973 off Port Lincoln, South Australia. Photographs of this specimen was published, revealing to the world the equally beautiful animal, covered in a web-like pattern of similar colouration as the shell. A carnivorous and predatory gastropod, it inhabits sandy to muddy bottoms of shallow to moderate depths around -10~50m. Today it is still considerably rare and highly sought-after by collectors. The attractive pattern is rather variable and the axial lines vary considerably in frequency among specimens. The two spiral bands may be solid or dotted when present, but they may also be completely absent. The form without spiral bands is rarer and was originally described as a separate species Voluta adcocki Tate, 1889; now considered a synonym but is still widely used as a form name in shell trade. Furthermore, the shoulder nodes are also rather variable in strength. Typical shell length around 45mm, extremely large specimens may exceed 65mm.
Netastoma darwinii (Sowerby II, 1849) <br /> PHOLADIDAE<br /> Inside sand rocks, San Jorge Gulf, Caleta Olvia, Santa Cruz, Argentina, 2004/i, Coll. Andres R. Bonard, 39.2mm <br /> <br /> The "Darwin's Piddock" is a spectacular South American pholadid with a very peculiar shape, ranging from southern Brazil to Argentina. A rock-burrowing bivalve, it repeatedly rotates its shells using a set of specially adapted muscles to mechanically grind a tubular burrow in soft rocks, which it then reside within for the rest of its life. It is a filter-feeder inhabiting very shallow to shallow waters down to about 15m deep, during feeding it extends its siphons out of the burrow but rest of the body remains protected by the rock. A rather rare species, perhaps owing to the fact that it is difficult to locate, and even more difficult to extract intact from its rocky burrow. Typical shell length around 30mm, very large specimens may exceed 40mm. The genus Nettastomella was erected by Carpenter in 1865 to house this eccentric species, but it is now deemed to be an unnecessary replacement name for genus Netastoma, its current genus.
Gigantopelta aegis Chen, Linse, Roterman, Copley & Rogers, 2015 <br /> PELTOSPIRIDAE<br /> -2785m, 'Tiamat Chimney', 37°47.03'′S, 49°38.97'E, Longqi hydrothermal vent field, Southwest Indian Ridge, ROV Kiel 6000 Dive 142 on-board RRS James Cook expedition JC67, 2011/xi/29, 40.2mm <br /> <br /> The "Aegis Shield" is a large hydrothermal vent endemic peltospirid known only from the Longqi (aka Dragon) hydrothermal vent field, Southwest Indian Ridge, Indian Ocean; which is a bathyal site around -2700~2800m in depth. It houses chemosynthetic endosymbiont bacteria in a much enlarged oesophageal gland, and appear to rely on these for nutrition. Interestingly both its shell and operculum are covered in a thick layer of iron oxide (i.e., rust), on the operculum especially this layer is a circular slab that can reach a thickness of 5mm. It is thus another "iron-armoured snail" like the 'scaly-foot gastropod' Chrysomallon squamiferum Chen et al., 2015. Most intriguingly however the 'scaly-foot', which it lives side-by-side with, has iron sulfide coating instead of iron oxide; it is not known why the two large peltospirids living in the same environment use different iron compunds to coat their exterior surface. Furthermore, its congener G. chessoia Chen et al., 2015 from Antarctic vents does not have such iron coating at all. The function (if any) of this coating is yet unclear, although microbial activity likely contribute to its formation. The specific epithet "aegis" refers to the renowned powerful mythical shield of Athena and Zeus from the Greek mythology; named for its great thickness and also the well-polished appearance which fits well with the description of the legendary shield which is sometimes described as "mirror-like". The bluish-white shell is quite thin, covered by a rather thick periostracum which is in turn covered by the thick rust layer. With an average shell length of 35mm and very large specimens reaching 44mm, it is a gigantic peltospirid only exceeded in size by C. squamiferum and G. chessoia. Although a common species in its habitat, due to the extreme difficulty in collecting specimens from hydrothermal vents, it is unfortunately a virtually unobtainable species for personal collection.
Gigantopelta chessoia Chen, Linse, Roterman, Copley & Rogers, 2015 <br /> PELTOSPIRIDAE<br /> -2646m, ‘Cindy's Castle’ hydrothermal vent site, 56°05.31′S, 30°19.10′W, E2 segment, East Scotia Ridge, By ROV Isis Dive 189 on-board RSS James Cook cruise JC80, 2012/xii/12, 45.9mm <br /> <br /> The "ChEsSO's Shield" is a large hydrothermal vent endemic peltospirid known only from the Antarctic deep-sea hydrothermal vents in E2 and E9 segments of the East Scotia Ridge, off South Sandwich Islands. The vent sites it inhabits are bathyal, around -2400~2600m in depth range. It houses chemosynthetic endosymbiont bacteria in a much enlarged oesophageal gland, and appear to rely on these for nutrition. With an average shell length of around 35mm and very large specimens exceeding 45mm, it is not only the largest peltospirid but also the largest member of the clade Neomphalina. Its size record is closely followed by the 'scaly-foot gastropod' Chrysomallon squamiferum Chen et al., 2015 (reaching 45.0mm) and its congener Gigantopelta aegis Chen et al., 2015 (reaching 44.2mm). The shell is rather thin but rigid, and covered by a thick olive to brown periostracum of a similar thickness. The operculum is unusually large for the family, most of which have reduced operculum or completely lost it, and covers the entire aperture. The genus name "Gigantopelta" is taken from "Giganto-", which means "giant" but is also an reference to the legendary Giants of the Greek mythology; and "pelta" meaning "shield", referring to the large operculum as well as the family name Peltospiridae. The specific epithet "chessoia" is taken from the ChEsSO (Chemosynthetic Ecosystems of the Southern Ocean) project, primarily funded by the Natural Environment Research Council, United Kingdom, which in 2010 first discovered and surveyed the Antarctic vents it inhabits. ChEsSO was part of the ChEss (Biogeography of Deep-Water Chemosynthetic Ecosystems) project in the Census of Marine Life initiative. Although a dominant species in its habitat, due to the extreme difficulty in collecting specimens from hydrothermal vents it is unfortunately a virtually unobtainable species for personal collection.
Samarangia quadrangularis (Adams & Reeve, 1850) <br /> VENERIDAE<br /> Dived, Zanpa-Misaki, Yomitan, Okinawa Island, Okinawa Prefecture, Japan, 2006/vi, 59.3mm <br /> <br /> The "Samarangia Clam" is a highly unusual venus clam with a peculiar habit of cementing sand grains over its shells to form 'pseudo-shells' that completely conceal the true shells, termed aranaceous coating. The sand grains are first held together by a mucus layer, and later become permanently concreted by aragonitic calcium carbonate. The function of this rather thick coating has been argued to be protective and camouflage, although no direct evidence has been presented. Surface of the arenaceous coating is ornamented with a number of prominent radial ribs, the strongest few being clearly nodulous. The underlying true shell is actually completely smooth and overlaid by a thin periostracum, the only way to see it is by removing the coating through intensive polishing. Its distribution range is quite wide in the Western Pacific from the Coral Sea to Honshu, Japan to Indonesia. Previously its range was thought to extend as far as Mauritius and Reunion, but recent studies have separated the Indian Ocean and Red Sea population as a distinct species -- Samarangia lewinsohni Mienis, 2011. A filter-feeding bivalve inhabiting sandy bottoms of rather shallow waters around -10~50m, it is not uncommon throughout its range. Typical shell length around 70mm, very large specimens may exceed 100mm.
Neancistrolepis glabra Habe & Ito, 1973 <br /> BUCCINIDAE<br /> -730~740m, 44°12'E 144°29'E, Trawled, Off Abashiri, Hokkaido, Japan, 2006/vii, 57.2mm <br /> <br /> Neancistrolepis glabra is a cold-water whelk with smooth, glossy periostracum ranging from Hokkaido, Japan to the Okhotsk Sea. A carnivorous and often scavenging gastropod, it inhabits sandy to muddy bottoms of quite deep water around -600~800m. It is a very rarely seen species on the international shell trade, even locally in Japan it is considered a rare species. In fully adult specimens, the outer lip thickens slightly and characteristically flares out, extending anteriorly. The periostracum is darker coloured in adults than juveniles and peels off rather easily when dried. The operculum is teardrop shaped and as usual for the genus Neancistrolepis it is much smaller than the aperture, though not as small as in the genus Parancistrolepis. Typical shell length around 100mm, very large specimens may exceed 140mm.
Spondylus crassisquama Lamarck, 1819<br /> SPONDYLIDAE<br /> -35~40m, Panama Bay, Panama, 2005/viii, 143.8mm <br /> <br /> Much better known by the name Spondylus princeps Broderip, 1833 which was recently synonymised with the current name, the showy "Pacific Thorny Oyster" gains its vernacular name from its distribution range in the Pacific Americas, from Baja California to Peru. Being rather variable in spine development and colouration it has a couple further synonyms including S. basilicus Reeve, 1856 which refers to an orange form, and S. dubius Broderip, 1833. Spondylus leucacanthus Broderip, 1833 with more sparce spines which are usually white was traditionally considered to be a form of this species but currently separated out as a valid species on its own right. A filter-feeding sessile bivalve like all spondylids, it lives attached to hard substrates around moderate depths of -10~50m. Typical shell length including spines around 100mm, very large specimens are known to exceed 170mm. Although a locally common species, specimens of fine quality are uncommon on the international shell trade market.
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