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.

Lyria cassidula (Reeve, 1849)<br />
VOLUTIDAE<br />
-40 m, Dived on sand and rubble bottom, Shizuoka Prefecture, Japan, 31.1 mm <br />
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The "Helmet Lyria" is a small volutid endemic to central and southern Japan, with a very robust shell ornamented with weak axial ribs. A carnivorous and predatory gastropod feeding on other invertebrate animals, it typically inahabits sand to rubble bottoms of shallow depths around 10~30 m deep but can rarely be found as shallow as the low tide line and as deep as 80 m. Overall an uncommon species, empty shells are often beached but it is surprisingly difficult to find live-collected specimens with operculum. One reason for this is that live specimens are simply rarely seen, but another reason is that the animal of Lyria will easily discard the posterior part of its foot -- where the operculum is attached to -- when attacked by a predator. This is thought to be an autotomic behaviour with the aim to distract the predator, and is also known from a number of other gastropod groups. Given time the foot will regenerate, sometimes with a new operculum which is typically deformed compared to the original one. As such, many live animals do no longer possess an operculum. <br />
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The shell form is somewhat variable in terms of the density of axial ribs, as well as the spire height. Colouration and patterning of the shell are extremely variable, though always with lighter background overlaid by numerous spiral lines and irregular, darker brown patches. The aperture colouration can range from white to deep orange. A subspecies name, L. c. pallidula Habe, 1962, was given to specimens with much lighter colouration that are usually from deeper depths, but this likely represents a mere deep-water form. Typical shell length around 30 mm, extremely large specimens may reach 45 mm.

Neopilina galatheae Lemche, 1957<br />
NEOPILINIDAE<br />
-2461 m, On glassy basalt on the top of a half-collapsed lava tower (0°48.2986’N, 86°13.1732’W), Galápagos Rift, Taken by suction sampler on ROV SuBastian dive #603, R/V Falkor (too) cruise Fkt231024, 2023/x/28, 26.8 mm <br />
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The legendary discovery of the first living monoplacophoran mollusc – Neopilina galatheae – trawled by the Galathea expedition from 3570 m deep off Costa Rica in 1952, was a sensational event in zoology of the 20th Century. This first finding of a whole class thought to be extinct since the Devonian (about 375 million years ago) made it one of the most famous “living fossils”. Every museum has a model of it, and it is mentioned in every biology course. But how many real specimens are there? Turns out, there are only 13 confidently identified specimens (and one fragment) collected on three occasions, until the specimen shown here was collected. <br />
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With 10 specimens, the Galathea trawl was a“jackpot”, as follow-up cruises set to obtain further specimens near the type locality returned empty handed except the Vema expedition, which successfully collected a single specimen from 3718 m deep in 1958. Then, three live specimens turned up off Baja California, Mexico in 1959 where they were trawled between 2781–2809 m deep, plus a fragment from a grab sampler at 1828 m. The specimen shown here was serendipitously collected from glassy basalt on the Galápagos Rift in October 2023, the first specimen to be collected in 64 years and the first time it was observed live on the seafloor. This finding extends its distribution range from Baja California, Mexico to Galápagos Rift in very deep waters between 1828-3570 m depth on both hard and soft substrata. Monoplacophoran molluscs are thought to be detritivores, though N. galatheae apparently also feeds on xenophyophores (giant protists). <br />
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Typical shell length around 30 mm, the largest specimen known is 37 mm, making it the largest living monoplacophoran. Some key morphological characteristics of this species are: five pairs of gills, well-developed postoral tentacles, apex being close to the anterior edge of shell, and the irregular concentric shell sculpture. It is the type species of genus Neopilina, which received its name for close morphological resemblence to the extinct tryblidiid monoplacophoran Pilina that lived between Ordovician and Silurian. The specific epithet was dedicated to the Danish HDMS Galathea whose expedition first recovered the species. <br />
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Read more for free in my preprint paper here: Chen C*, Jamieson JH (Preprint). In situ observation and range extension of the first monoplacophoran Neopilina galatheae. bioRxiv, https://doi.org/10.1101/2023.11.08.566290

Panopea bitruncata (Conrad, 1872) <br />
HIATELLIDAE<br />
-1 m (-3.5 ft.) deep in sticky mud at extreme low tide (-0.3 m / -0.9 ft.), Dug up in mud flats to the northwest (gulf side) of Islamorada Key Bridge, Florida Keys, Florida, U.S.A., 1971/xii/04, 183.3 mm <br />
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The "Atlantic Geoduck" is a very large hiatellid clam living buried very deep in soft mud, from where it filter-feeds by extending a very large, elongate, fleshy siphon above the sea bottom. Found in shallow to moderate depths between extreme low tide to at least 50 m deep on the Atlantic coast of North America, its confirmed range is from Chesapeake Bay around Virginia to Florida (where most specimens have been found) to Texas in the northern Gulf of Mexico. This may extend further southwards, as there are unconfirmed records from Yucatán Peninsula in Mexico. <br />
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Unlike the better-known congener inhabiting the Pacific coast of North America -- the "Pacific Geoduck" Panopea generosa Gould, 1850 -- which is very common and widely used for seafood, living P. bitruncata is very rare. Until 1960's when definitive live-taken speciemns were collected, the recent material was only known from disarticulated empty shells and some authors considered it to be extinct. It is however a common constituent of Pliocene formations on the eastern U.S.A. such as at the Caloosahatchie, Shell Creek and Alligator Creek formations. <br />
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For years whether the Pliocene fossils and the living individuals belong to the same species was debated, finally settling on the agreement that they are conspecific. There is some evidence that adult clams are unable to re-burrow once they are dislodged on to the seafloor from storms or other factors. Typical shell length around 150 mm, very large specimens can exceed 220 mm.

Calliostoma bellatrix Willan, 2002<br />
CALLIOSTOMATIDAE<br />
Trawled, Torres Strait, Australia, 38.5 mm <br />
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A broad trochoid shell ornamented with two spiral rows of strong beads, one at and another just above the suture to generate a 'double-keeled' impression, makes the "Bellatrix Top" distinct from other described calliostomatids. Ranging from northern Australia through Timor Sea to southern Indonesia, it inhabits soft bottoms on the continental shelf between around 200~400 m deep. Though its specific diet is unknown, it is most likely a carnivorous grazer feeding on other invertebrate animals such as corals and sponges, as is typical for other calliostomatids. Typical shell diameter around 35 mm, very large specimens may reach 45 mm. <br />
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The shell surface is irregularly marked with reddish brown axial streaks, and is strongly iridescent so that under strong light the shell appears to glow. This was the inspiration for its name -- Bellatrix, the third brightest star in the constellation of Orion. The broad, 'double-keeled' shell plus the lack of significant sculpture on most of the subsutural ramp are sufficient to distinguish it from other Calliostoma species. Though currently placed in a different genus, Bathyfautor coriolis Marshall, 1995 from New Caledonia is morphologically similar -- though that species has a much narrower shell with much weaker peripheral keels.

Cirsotrema bennettorum García, 2000<br />
EPITONIIDAE<br />
-300 m, Dredged, Grand Passage, New Caledonia, 26.9 mm <br />
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Known only from moderately deep waters between 200-500 m depth off New Caledonia, the "Bennett's Wentletrap" is a highly characteristic epitoniid with a tall turbinate shell shape ornamented by dense blade-like axial lamellae. Some of these lamellae are thickened as strong varices, although the number and frequency of such varices are very variable among individuals and also among different whorls within the same individual. Otherwise the shell is little-varied and always white. On adult shells the first few whorls are almost always lost. Though the feeding ecology is unknown, it is most likely a parasitic gastropod living on and around sea anemone hosts upon which it feeds, like other epitoniids. Typical shell length around 25 mm, very large specimens may approach 35 mm. A rare species, most specimens known have been dredged on sandy bottom. Its shell morphology and sculpture are unique among known epitoniid species, and it is thus easily identified. It was named in honour of Jo (and Charles George "Rusty" Bennett, shell collectors from Florida, U.S.A.

Oocorys tosaensis Habe & Azuma, 1959<br />
CASSIDAE<br />
-400~600 m, Trawled, Pratas Islands, South China Sea, 33.2 mm <br />
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Characterised by a thick, solid shell with a narrow, open umbilicus and coarse spiral ribs, Oocorys tosaensis is a deep-water cassid ranging from the southern half of Japan to Taiwan to South China Sea. Used to be an extremely rare and virtually unobtainable species, in the recent years some specimens have been trawled off Pratas Islands in the South China Sea. Nevertheless, it remains a rare species and live-collected specimens are especially hard to comeby. Inhabiting sandy to muddy bottoms between 200~600 m deep, it is a carnivorous and predatory gastropod feeding primarily on echinoderms. Typical shell length around 30 mm, very large specimens can exceed 40 mm. When alive the shell is covered by a layer of semi-transparent, greenish brown periostracum. Though some authors have considered it to be a junior synonym of the very variable Oocorys verrillii (Dall, 1889), this is unlikely due to the extremely consistent shell morphology of O. tosaensis -- most notably the open umbilicus that is missing in O. verrillii. Though once placed in the genus Hadroocorys, this is now considered to be a junior synonym of Oocorys.

Euhadra senckenbergiana (Kobelt, 1875)<br />
CAMAENIDAE<br />
Mt. Norikura, Takayama, Gifu Prefecture, Japan, 51.0 mm <br />
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One of the most spectacular native landsnails of Japan, Euhadra senckenbergiana or the "Kuroiwa's Euhadra" as it is locally known, is widely distributed in Honshu Island from the Tohoku Region to Kyoto Prefecture; the centre of distribution is in central Honshu across Ishikawa, Fukui, Gifu, Nagano, and Niigata Prefectures. A rather rare species inhabiting forest floors, it prefers dense primeval forests and is a herbivorous grazer feeding on a variety of plant matter. Like many Euhadra species it can be very variable in colouration, the specimen shown is a typical specimen from highlands of the central Honshu region with rather irregular, thick axial growth lines overlaid with intermittent yellowish lines that form a flame-like pattern across the shell surface. Even within the same population, the pattern development can vary greatly. With an average shell diameter of 50 mm and the largest specimens reaching 60 mm, it is the second largest landsnail species native to Japan only after Euhadra awaensis (Pilsbry, 1902) which can exceed 65 mm. Its Japanese vernacular name is dedicated to the Japanese naturalist Hisashi Kuroiwa (1858-1930) who extensively studied the wildlife of Okinawa. <br />
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Though several subspecies names have been proposed for various populations with different morphological characteristics, the status of those names are mostly in a state of flux. For example, Euhadra awaensis was once considered a subspecies of E. senckenbergiana, but is now generally accepted as a separate valid species. The name E. s. ibukicola Pilsbry, 1928 was proposed for a smaller population narrowly distributed only in Mt. Suzuka and Mt. Ibuki, but is now thought to be a mere junior synonym. One subspecies that is still considered to be valid by most is E. s. notoensis Kuroda & Teramachi, 1954 inhabiting plains of the northern Honshu from Ishikawa to Niigata Prefectures, which has a brighter background colouration and lacks the flame-like patterns.

Chicoreus ramosus (Linnaeus, 1758)<br />
MURICIDAE<br />
Dived in shallow water, Sandakan, Sabah, Malaysia, Borneo Island, 230.2 mm <br />
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The "Ramose Murex", also known as the "Branched Murex", is the largest living muricid species known with a shell length averaging around 200 mm and the largest specimens exceeding even 330 mm. A very widely-distributed species commonly seen across the entire Indo-West Pacific, it is found from South Africa to Japan to Australia, including Red Sea. The solid shell can be very variable in spine and siphonal canal development, from extremely elongate to short and stubby. Adult shells are typically white with some patches showing brownish spiral lines, but juveniles can be very colourful ranging from white to bright orange to almost completely black. The inner lip is usually brightly coloured, commonly pink or orange. <br />
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A carnivorous and predatory gastropod, it inhabits sand or rubble bottoms near coral reefs from low intertidal down to about 30 m deep and feeds on other molluscs, chiefly bivalves. As such, it is often considered a pest of bivalve aquaculture such as oysters or pearl oysters along with fellow muricids. Due to its rather large size and edible flesh, it is a important species for fisheries in some countries like India. The shell is commonly sold as decoration and can be easily found around the globe, though large, specimen-grade shells are surprisingly difficult to come by. It lays large clusters of about 400 eggs, each about 20 mm in length.

Pyrulofusus melonis (Dall, 1891)<br />
BUCCINIDAE<br />
-300 m, Trawled on mud, South of Pribilof Islands, Bering Sea, Alaska, U.S.A., 2010/vii, 127.2 mm <br />
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Characterised by numerous slightly wavy axial ridges crossing with numerous very fine spiral lines, the "Melon Shaped Whelk" is a large cold-water buccinid native to the Bering Sea. Like many Bering Sea buccinids, it inhabits a very wide bathymetric range from shallow subtidal waters around 20~30 m to over 400 m deep; most specimens are trawled between 100~300 m deep. As is typical for genus Pyrulofusus, it is a direct developer that hatch as crawling juvenile snails from very large egg cases around 40~50 mm in diameter. <br />
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Though supposedly common in its natural habitat, it is a uncommonly collected species due to its inaccessible range in the Bering Sea. A carnivorus and preadatory snail, it feeds mostly on other invertebrate animals. The shell is somewhat variable in terms of the density of axial ridges, as well as the height-to-width ratio. The aperture colour can be yellow or white, fresh specimens carry a purple hue which unfortunately quickly fades. Typical shell length around 120 mm, very large specimens can reach 160 mm. The unique undulated shell surface from the irregular, wavy ridges serves as the key character that immediately distinguishes it from other congeners.

Stirpulina ramosa (Dunker, 1882) <br />
CLAVAGELLIDAE<br />
Shizuoka Prefecture, Japan, 98.6 mm <br />
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A truly ecccentric and extraordinary bivalve, Stirpulina ramosa is a 'watering-pot' clavagellid that during development stops growing its bivalved shell and abruptly switches to growing a calcareous tube. Although an array of other superficially similar genera such as Brechites and Nipponoclava are known in the superfamily Clavagelloidea, recent researches have revealed that the bizarre life style of building an adventitious tube and living buried in the sand in fact evolved twice within the superfamily Clavagelloidea, once in Clavagellidae and once in Penicillidae. All other such genera belong to the Penicillidae radiation, and Stirpulina ramosa is the only extant member of the genus. This makes it the only surviving endobenthic tube-dwelling clavagellid in the world, a remnant species from Late Cretaceous and a "living fossil". All other living clavagellid species live a sessile life cemented to hard substrates and do not live buried in sand. A clear difference from the penicillids is that it only has the left valve cemented to the calcareous tube, whereas all tube-building penicillids have both valves cemented. The right valve remain free and mobile within the tube. Another difference is that the 'watering-pot' end of the tube consists of bifurcating tubules, a feature not seen in the 'watering-pot' of penicillids. <br />
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An endemic species of Japan inhabiting sand and gravel bottoms -50~200m deep south of Chiba Prefecture, it is a filter-feeder and the tip of its tube is always protruded slightly from sand to access sea water. A very uncommon species, usually only shattered empty tubes are collected; live-collected specimens are extremely scarce. The only recorded specimen with soft parts preserved was housed in the collection of Emperor Shōwa Hirohito, and this was dissected by the eminent malacologist Prof. Brian Morton in order to reveal the anatomical differences with penicillids. Typical length of the adventitious tube around 70mm, extremely long tubes may exceed 100mm.

Amoria subfossilis Bail & Limpus, 2011<br />
VOLUTIDAE<br />
Trawled, Off Swain Reefs, Queensland, Australia, 107.4 mm <br />
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The "Subfossil Volute" is a poorly known volutid that has so far only been found off Swain Reefs in Queensland, Australia. It is a very rare species and all known specimens were supposedly trawled in deep water and were found as empty shells, hence the name. The characteristic golden zigzagged axial pattern and the yellowish cream background colouration are typical of subfossil volutids and suggest these shells have been dead for quite some time, although the exact time is unclear. It has been hypothesised as an extinct species, but it remains possible that a living population exists but has simply not been sampled. Given this situation, we know nothing about its ecology and true habitat, though it is almost certainly a carnivorous and predatory gastropod like other volutids. Typical shell length around 100 mm, very large specimens may approach 120 mm. <br />
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Among living Amoria it is most similar to A. jansae van Pel & Moolenbeek, 2010 which also occurs in Queensland. The two species can be distinguished based on A. subfossilis having a much wider shell with a stronger and sharper flaring of the outer lip. Typically the shell patterning of A. jansae is much darker in colouration, but this is most likely due to the shells of A. subfossilis fading rather than a real difference between the two species. They are both representatives of the subgenus Cymbiolista, which some consider to be a mere junior synonym of Amoria.

Lyria leslieboschae Emerson & Sage, 1986<br />
VOLUTIDAE<br />
-10~15 m, Dived, Off Masirah Island, Oman, 2020/xii, 89.9 mm <br />
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Characterised by a high-spired shell with evenly dotted, closely spaced axial ribs and a diffused flame-like axial pattern, the "Leslie Bosch's Lyria" is a volutid endemic to Oman where it is only known from Masirah Island. Like many Omani mollusc species, it was first discovered by Dr Donald Taeke Bosch (1917-2012) and Eloise Bosch (1919-2016) who authored the book "Seashells of Oman" (1983). Donald Bosch was an American medical officer and Eloise Bosch was a teacher, and since they arrived in Oman in 1955 they became active as amateur conchologists, finding over 20 mollusc species new to science. <br />
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Lyria leslieboschae was discovered in January 1985 beached on the eastern side of Masirah Island, a total of four empty beached shells were sent to the American Museum of Natural History for study and subsequently described in 1986 by the malacologists Dr William Keith Emerson (1925-2016) and Walter Elmer Sage III (1949-1995). Named after Leslie Bosch, daughter-in-law of Donald and Eloise Bosch, this exquite species dissapeared for over three decades since Donald and Eloise Bosch retired -- until the recent reignition of collecting activities in Oman around 2020 by a few conchologists which led to the finding of at least a couple dozens of specimens. Nevertheless, it remains an extremely rare and sought-after species today and it has still only been found as empty beached shells or crabbed in shallow waters. Its true habitat remains undiscovered, but given most specimens have been found beached after severe storms, it likely inhabits moderate depths over 30 m deep off eastern Masirah Island. Its exact diet is not known, but it is probably a carnivorous and predatory gastropod like other volutids. Typical shell length around 90 mm, very large specimens can approach even 130 mm. <br />
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Though it is difficult to confuse with other Lyria species, it is morphologically closest to Lyria lyraeformis (Swainson, 1821) which has a more southernly distribution between Somalia and Mozambique. The two species can be easily distinguished based on the following key features: 1) the protoconch of L. leslieboschae is blunt and lacks a sharp calcarella characteristic of L. lyraeformis; 2) the outer lip of adult L. leslieboschae is sigmoid and ends in a narrow posterior canal but is simple in L. lyraeformis; 3) the flame-like diffused axial pattern of L. leslieboschae is lacking entirely in L. lyraeformis.

Cardilia semisulcata (Lamarck, 1819)<br />
CARDILIIDAE<br />
Shizuoka Prefecture, Japan, 18.7 mm <br />
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An unusual shell morphology with very inflated and higher-than-long valves, Cardilia semisulcata belongs to the little-known bivalve family Cardiliidae. Despite being a widely distributed species in the Indo-West Pacific with records ranging from central Japan to Queensland, Australia to Oman, it is a very rare species virtually only seen as disarticulated, beached shells after storms. Even such single valves are scarce and are highly prized by beachcombers, few live-taken specimens with both valves are known. <br />
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Virtually nothing is known about its ecology, except that it lives buried in sand or mud between about -5~30 m deep. If the placement of Cardiliidae in Mactroidea is indeed correct (as is suggested by the hinge morphology) this would imply that cardiliids are most likely filter-feeders, though this requires further evidence. The holotype was supposedly collected from South Australia, but as it has never been seen south of New South Wales in Australia, this is likely erroneous. Typical shell length around 15 mm, very large specimens may reach 30 mm. <br />
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Due to superficial similarity to glossids with the strongly raised umbo, it was originally described as Isocardia semisulcata (Isocardia now a junior synonym of Glossus) in Glossidae. In 1835 the French paleontologist and malacologist Gerard Paul Deshayes (1797-1875) recognised its uniqueness and placed it in a new genus, Cardilia. Today Cardilia remains the only genus in Cardiliidae, and despite four living and 11 fossil species being recognised it remains one of the least studied bivalve families. In Japan it is known as "Kisa-Gai" (literally meaing "Elephant Shell"), due to the coiled umbo of each single valve vaguely resembling elephant noses.

Aporrhais elegantissima Parenzan, 1970<br />
APORRHAIDAE <br />
-30~50 m, Trawled, Off Dakar, Senegal, 58.7 mm <br />
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Ranging along the western African coast between Mauritania and Angola, the "African Pelican's Foot" is a medium-sized aporrhaid snail typically carrying four spine-like digitations on the adult shell. A detritivorous gastropod species found on soft bottoms of moderate depths between 30~200 m deep, it is a common species and most specimens originate from Senegal. Though it has supposedly also been recorded from Morocco and Mediterranean Sea, these are not associated with reliable specimens and require further evidence to confirm. Two forms are known, with the smaller, short-spined form (typical shell length around 30 mm) being much more abundant than the larger, long-spined form (shown, typical shell length around 50 mm). Very large specimens of the latter form may reach 80 mm. The reason behind these two morphologically separable forms is unclear -- although sexual dimorphism as well as impacts of salinity and temperature has been suggested as possible explanations, the possibility that these represent two independently evolving lineages cannot be discarded at this time. <br />
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Ever since its description it has been confused with the closely related A. pesgallinae Barnard, 1963, with the two being considered synonyms since 1976. However, in a 2019 paper by Ulrich Wieneke and Virgilio Liverani it was clarified that A. pesgallinae is actually a distinct deep-water species endemic to 300~450 m deep off Namibia, reinstating A. elegantissima as a separate species in its own right. The two species differ in shell morphology where A. pesgallinae has a larger, wider spire with more compressed spire angle and stronger keels on the last whorl, more clearly sickle-shaped base in the abaxial digits, and a white colouration instead of brown, when compared to A. elegantissima. Both of these species are thought to hybridise with A. senegalensis Gray, 1838, producing the few known shells combining characteristics of both parent species.

Scutellastra kermadecensis (Pilsbry, 1894)<br />
PATELLIDAE<br />
Lowtide on rock, Raoul Island, Kermadec Islands, New Zealand, 1967/vii, 80.3 mm <br />
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The "Kermadec Limpet", as its name suggests, is a pattelid true limpet endemic to the Kermadec Islands of New Zealand. A key highlight of this species is its size -- with an average shell length around 120 mm and giant specimens said to exceed even 170 mm, it is one of the largest species of extant true limpets. <br />
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Because it is so different and so much larger than any other true limpets known from around New Zealand and Australia, shortly after its description fierce debate ensued regarding its type locality. The malacologist John William Brazier (1842-1930) believed it was extremely unlikely that such a large limpet had remained undiscovered in the Kermadecs despite known expeditions already visited these islands, he hypothesised that this species is more likely to originate from South Africa, where many species of large-sized true limpets are known. Fortunately, the original locality of Kermadec Islands could be verified by Thomas Federic Cheeseman (1845-1923), curator of the Auckland Museum in New Zealand who collected the first specimens (including the type series), testifying that these limpets were numerous on the rocky shores surrounding a number of islands in the Kermadecs and that previous expeditions likely missed them because they landed in sandy beach instead of rocky shores. <br />
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Indeed, research visits to the Kermadecs later proved that this species is very common on these islands; but as since 1977 the Kermadecs have become a nature reserve with collections strictly forbidden, this species is now rarely seen in private collections. The shell is characterised by numerous strong radial ribs, although most large specimens have the dorsal surface completely eroded away. Younger individuals have a narrower shell with darker colouration (as shown), which then becomes broader, more rounded in shape, and lighter in colour with time. A herbivorous grazer, it feeds on algae growth on the rocky shore and inhabits very shallow waters in the lower intertidal.

Inquisitor elegans Bozzetti, 1993<br />
PSEUDOMELATOMIDAE<br />
-40~50 m, Trawled, Off Colochel, Tamil Nadu, India, 2023/i, 70.0 mm <br />
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A peculiar shell morphology with a broad, rounded subsutural ramp and a domed spire characterises the "Elegant Inquisitor", a handsome and rarely seen pseudomelatomid "turrid" snail native to the northern part of Indian Ocean. First described from four specimens trawled off Ras Hafun, Somalia, it was later also found off India; although it has not been recorded with certainty between these two localities, this is likely linked to biased sampling effort instead of representing a truly disjunct distribution. Most specimens have been dredged or trawled in moderate depths between 50~200 m deep on sandy bottoms. <br />
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Anterior to the prominent subsutural ramp, the shell carries a latticed sculpture where the axial ribs are much stronger than spiral ribs and is coloured by two to three broad spiral bands of reddish brown. These features make its shell not only instantly separable from other Inquisitor species but also quite attractive, and with rarity added on top it has become a much sought after species. Though almost certainly a carnivorous and predatory species feeding on invertebrate animals, no information is available regarding its feeding ecology. Typical shell length around 50 mm, very large specimens like the one shown can exceed 70 mm.

Marginellona gigas (von Martens, 1904)<br />
MARGINELLONIDAE<br />
-400 m, Trawled on muddy bottom, Spratly Islands, South China Sea, 2010, 193.9 mm <br />
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A species famed for its convoluted taxonomic history, the "Pratas Volute" is now placed in neither Volutidae nor Marginellidae but instead in Marginellonidae. Initially described from a single specimen collected from 805 m deep off Nicobar Islands by the German Valdivia Expedition (1898-1899), certain similarities to volutids were noted but it was placed in Marginellidae largely based on the strange radula morpholology with a very wide central teeth bearing numerous cusps, similar to some radula known from other marginellids. Then later in 1967 the American malacologist Herald A. Rehder (1907-1996) named the same species again as Sigaluta pratasensis Rehder, 1967 based on specimens dredged by the American research ship "Albatross I" in 1907-1909 off Pratas Islands, South China Sea. Apparently unaware of von Martens' earlier work, Rehder only examined the shell morphology and placed it in Volutidae. This started a long confusion on whether this species should be placed in Marginellidae or Volutidae -- although radula features indicated the former, the very large size of this species with shell length averaging at around 120 mm being monstrous for Marginellidae and more typical for Volutidae. <br />
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In 1991 malacologists "Jerry" Harasewych and Yuri Kantor examined newly obtained specimens in detail, finding anatomical characters like the presence of a buccal caecum and a simple stomach that supported its placement in Marginellidae. So there it was sitting in subfamily Marginelloninae under Marginellidae until 2019, when the first molecular phylogeny to investigate it surprisingly found it to be sister to a group containing both Marginellidae and Cystiscidae. As such, Marginelloninae was moved outside of Marginellidae as a new family-level group, Marginellonidae. Currently Marginellonidae houses this species together with Afrivoluta pringlei Tomlin, 1947, another large-sized species found off South Africa that was also once placed in Volutidae. <br />
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Now we know its distribution to range from east Indian Ocean off Nicobar Islands to East China Sea, though it is by far most abundant in the South China Sea off Pratas Islands where it is a common fisheries by-catch between 300~1000 m depth. A carnivorous and predatory gastropod feeding on other invertebrate animals, it is found on both sandy and muddy substrates. Though generally instantly recognisable, specimens do vary in spire height and therefore the shell height to width ratio. Individuals mature at drastically different sizes, ranging from dwarf individuals maturing (with thickened lip) at around 60 mm and giants at over 210 mm. At its maximum size, it is by far the largest of all "marginelliform" gastropods (families Marginellidae, Cystiscidae, Marginellonidae). A few albino specimens with completely white shells have been found.

Conchocele koyamai Habe, 1981<br />
THYASIRIDAE<br />
Shizuoka Prefecture, Japan, 37.8 mm <br />
<br />
Characterised by a peculiar 'stepped' shell form where two well-defined posterior folds and two strong ridges divide each valve into five distinct regions, the "Koyama's Cleftclam" is a thyasirid bivalve endemic to central Japan on the Pacific side of Honshu Island with a range approximately between Wakayama Prefecture and Chiba Prefecture. The holotype is an empty left valve collected by in prawn dredge off Cape Shionomisaki, Wakayama Prefecture measuring 21.0 mm in length; for a long time this was thought to be the only known specimen. <br />
<br />
Though a few articulated specimens have been collected in recent years by dredges or deep-diving in sandy bottoms between 50~100 m deep, it remains an extremely rare species and highly sought after by Japanese collectors. A number of empty, disarticulated valves have even been beached-collected in Chiba Prefecture but such discoveries are also very scarce. No information is available on its ecology, and therefore its feeding habits are unknown; though it likely hosts sulfur-oxidising bacteria as symbionts on its gill like may other thyasirid species. Typical shell length around 25 mm, very large specimens like the one shown here can exceed 35 mm. <br />
<br />
Although described as a member of genus Conchocele, many of its conchological features do not align well with typical Conchocele. These include 1) the presence of a well-definied second posterior fold (termed submarginal sulcus), 2) numerous conical granules on the shell surface, and 3) numerous radial striations on the inner surface of the shell. As such, the need to make a new genus to house this species has been discussed but not yet realised. Due to these features, it cannot be confused with any other known thyasirid species. Its namesake was not clearly stated in the original description, but is most likely the Japanese conchologist Yasuo Koyama who was based in Wakayama Prefecture and was the first to collect many species (likely also this one).

Niso hendersoni Bartsch, 1953<br />
EULIMIDAE<br />
-27 m (-90 ft.), Dredged, Off St. Augustine, Florida, U.S.A., Leg. Michael Cahill, 1970's, 39.2 mm <br />
<br />
The "Beautiful Niso" is a highly unusual eulimid with a striking pattern on the shell, unlike most species which lack pattern altogether. A rare species and among the most coveted collector's item in the family, it ranges between North Carolina and Florida, U.S.A. and inhabits sandy bottoms of moderate depths around 20~200 m deep. Eulimids feed exclusively on echinoderms which they parasitise, the genus Niso is known to parasitise sea stars and N. hendersoni probably does the same. Like other species of Niso, it is most likely hemiparasitic and spends most of its time free-living and only attach to the host when feeding. Typical shell length around 25 mm, very large specimens may reach even 45 mm. <br />
<br />
It was named in honour of John Brooks Henderson Jr. (1870-1923), an American conchologist who was associated with Smithsonian Institute and carried out hundreds of dredges off Florida on his private yacht "Eolis", collecting numerous species undescribed at the time -- including this one. Morphologically it is very similar to its Pacific sister species Niso splendidula (Sowerby I, 1834) which ranges between Gulf of California to Ecuador. Though the two species have very similar pattern, the spiral bands on N. splendidula carry more closely spaced axial lines and darker in colouration. Due to the large size and the characteristic shell pattern, N. hendersoni cannot be confused with any other known eulimid species.

Fulgoraria elongata Shikama, 1962<br />
VOLUTIDAE<br />
-550 m (-300 fms.), Trawled, Off Chōshi, Chiba Prefecture, Japan, 1961, Ex-Coll. Tokio Shikama, 128.6 mm <br />
<br />
Characterised by an exceptionally narrow and thin shell for the genus, the "Elongate Japanese Volute" is a volutid only known from a small area east off Chiba Prefecture, Japan. A carnivorous and predatory gastropod, it inhabits sandy to muddy bottoms of rather deep waters around 200~800 m depth (majority from below 500 m) and most likely feeds on other invertebrate animals as is typical for members of genus Fulgoraria. Perhaps the rarest volute found around the Japanese Archipelago, only several dozens of specimens are known and mostly with broken lips due to its thin and frail shell structure. Its rarity can be partly attributed to its narrow range and the deep, inaccessible habitat, though it does also appear to naturally occur in low densities. The Japanese malacologist and paleontologist Tokio Shikama (1912-1978) who named it accumulated a number of specimens over the years, many of which later ended up in other collections. <br />
<br />
The shell surface is sculptured by about 20 axial folds per whorl, strongest at the early teleoconch whorls and diminishing with growth. Typically, a sparse and irregular zigzagged 'lightning' axial pattern is present on the teleoconch whorls. Two to three weak columellar folds are present, though only one may be clearly visible from the aperture. Typical shell length around 150 mm, very large specimens are known to reach even 200 mm. This species is often confused with the tall-spired form of the much more common Fulgoraria kaneko Hirase, 1922, not because the two species are similar morphologically but because specimens of F. kaneko have been illustrated erroneously under the name of F. elongata in key identification guides for the group like "Volutes" (1992) by Poppe & Goto. Fortunately, this was corrected in the "Conchological Iconography" of Fulgorariinae by Pilsbry & Olsson (1954). The real F. elongata is much closer to the F. megaspira (Sowerby I, 1844) complex, but is distinct in having an exceptionally elongate and thin shell, as well as the much deeper habitat depth.

Calliostoma rosewateri Clench & Turner, 1960<br />
CALLIOSTOMATIDAE<br />
-250 m, Collected by the submersible "Curasub", Curaçao, Lesser Antilles, 2014, 28.5 mm <br />
<br />
A lustrous and radiant shell with finely beaded double-keeled shoulder characterises the "Rosewater's Top", a beautiful Caribbean calliostomatid ranging from Florida, U.S.A. to Trinidad and Tobago. A carnivorous grazer inhabiting hard bottoms of rather deep waters ranging between about 200~500 m depth, it most likely feeds on corals and other sessile animals as is typical for calliostomatids. Though overall a little-varied species, the development of dark colour patches on the shell vary greatly among individuals; these patches carry violet hue when fresh but rapidly fades to reddish brown. The shell surface carries a metallic, golden sheen, making this rather rare species a much coveted collector's item. <br />
<br />
Typical shell diameter around 30 mm, though very large specimens may reach even 45 mm. Among the many closely-related deep-water Caribbean calliostomatids with beaded spiral cords, it is perhaps most similar to Calliostoma oregon Clench & Turner, 1960 which also has a double-keeled shoulder. These two species are separable in that the shell of C. oregon has straight sides to the spire as opposed to the slightly concave ones in C. rosewateri, and that O. oregon has fewer spiral cords with coarser beading. The shell size of C. oregon is much smaller than C. rosewateri, being typically only around 20 mm and the largest individuals reaching just 30 mm.

Offadesma nakamigawai Kuroda & Horikoshi, 1952<br />
PERIPLOMATIDAE<br />
Shizuoka Prefecture, Japan, 51.2 mm <br />
<br />
An unusual periplomatid bivalve, the "Nakamigawa's Lantern Shell" is characterised by a paper-thin, strongly inequivalve shell where the left valve is much smaller than the right valve which envelopes it. Originally described based on a single specimen with damaged but articulated valves collected off Zushi in Sagami Bay, it is usually considered an endemic species of central Japan -- though a morphologically similar specimen was collected in the Philippines in 2014 and may represent a significant range extension. The holotype was collected by Korokuro Nakamigawa, a Japanese collector living in Kamakura, after whom this species was named after. Living in subtidal waters down to about -70 m deep, it usually remains buried in soft or sandy mud and is an infaunal filter-feeding bivalve. A transverse crack is present near the umbo, a feature typical of Periplomatidae and Laternulidae; the ligament is attached to large, spoon-like chondrophores. Typical shell length around 50 mm, very large specimens can reach 75 mm. <br />
<br />
An exceedingly rare species, it is mostly known from broken fragments washed up on shore after storms, articulated valves being virtually impossible to obtain. In addition to its apparently intrinsic low population density, an important reason for this is that the valves are very brittle and being aragonistic they rapidly disintegrate after the animal’s death. With a graceful Japanese name literally meaning the "long-tailed celestial robe of the dragon palace" ("Onaga-Ryugu-Hagoromo") added on top of its scarcity, it has attained a mythical status among Japanese collectors and a most sought-after species. The renowned Japanese palaeontologist and malacologist Tokio Shikama (1912-1978) wrote about the only specimen in his collection "I thought I was dreaming when I collected this species" (Selected Shells of the World Illustrated in Colours Vol. II, 1964), and another famed malacologist Katsura Oyama (1917-1995) was said to have greatly cherished a mere fragment of a shell in his collection. <br />
<br />
Among living bivalves it can only be confused with one species, its only extant congener Offadesma angasi (Crosse & Fischer, 1864) ranging from Australia to New Zealand. Although the original description of O. nakamigawai quotes larger size and a more inflated shell as key features separating it from O. angasi, the holotype of O. nakamigawai is only 74 mm in shell length which is smaller than the typical size of O. angasi (80 mm, up to 100 mm). The inflation of valves is also similar among the two species when examining a larger series of O. angasi. These two species are actually more readily separable in that the left valve of O. nakamigawai is much smaller than the right valve whereas in O. angasi they only differ very slightly. Typically, O. nakamigawai also has a more clearly constricted posterior beak than O. angasi but both species are somewhat variable in overall shell form and this is not always obvious. These two species are clearly very similar and the true relationship between them warrants molecular studies plus hopefully the finding of more specimens from geographically intermediate localities like the Philippines.

Morum lindae Petuch, 1987<br />
HARPIDAE<br />
-120 m, Trawled on sandy bottom, Off Cabo de la Vela, Guajira Peninsula, Colombia, 1990’s, 41.1 mm <br />
<br />
An intricately sculptured harpid with a broad shoulder and ornamented with criss-crossing axial and spiral ribs, the "Linda's Morum" is a Caribbean species ranging between Colombia and Venezuela. Inhabiting moderately deep waters around -50~200 m, it most likely feeds on small crustaceans like other Morum species. A rather rare species, vast majority of the known specimens have been trawled or dredged off Colombia. The overall colouration is rather variable and can range from light tan to very dark purple, specimens with dark colouration are extremely rare. Similarly, the columellar shield can vary in colour from white to dark purple. Typical shell length around 35 mm, very large specimens may reach 45 mm. <br />
<br />
This species was named in honour of Linda Petuch, wife of the malacologist Ed Petuch who named it. It is most closely allied to Morum dennisoni (Reeve, 1842) with which it co-occurs in the western Atlantic. The two species have sometimes been confused, but are actually easily separable in that M. lindae has much stronger axial sculpture with the varices becoming raised like sharp blades and typically has a stronger shoulder compared to M. dennisoni.

Paralepetopsis polita Chen, Zhong, Qiu & Sun, 2023<br />
NEOLEPETOPSIDAE<br />
Top & Left: Paratype #1 (NSMT Mo-79367), 7.0 mm; Right: Holotype (TMBC031004), 7.9 mm; Bottom: Paratype #2 (NSMT Mo-79368), 6.4 mm <br />
-1361 m, On the shell of the vesicomyid clam Archivesica marissinica, Haima methane seep (16°41.6561'N, 110°23.8165'E), South China Sea <br />
<br />
A deep-sea limpet with a smooth, semi-transparent shell, Paralepetopsis polita is so far only known from the Haima methane seep in the South China Sea. A grazing gastropod, it usually lives on the shell surface of the large vesicomyid clam Archivesica marissinica Chen, Okutani, Liang & Qiu, 2018 (which has symbiotic bacteria living inside its gill cells that oxidise hydrogen sulfide to generate energy) and is thought to feed on the bacterial film growing on the clam. Typical shell length around 5 mm, very large specimens may exceed 8 mm. Although only uncommon at the Haima seep, the restricted and deep nature of its preferred habitat means it is very rarely collected and only a few specimens are known at the moment. <br />
<br />
It has a characteristically neolepetopsid-type radula with articulating shafts and a solid central tooth, but molecular phylogeny surprisingly nested it within Lepetidae instead. This indicates there are likely two separate lineages of true limpets with this radula type, and molecular data for the type species of Paralepetopsis is needed in the future to resolve the position of this genus. The smooth, thin shell with a straight to concave anterior slope differentiates it from other species currently assigned to Paralepetopsis.

Shinkailepas conspira Beck in Chen & Sigwart, 2023<br />
PHENACOLEPADIDAE<br />
Holotype (MNHN-IM-2000-38688)<br />
-1842 m, Hine Hina hydrothermal vent site (22°32'S 176°43'E), Lau Basin, Taken by the manned submersible HOV Nautile, BIOLAU cruise dive BL01, 1989/v/13, 21.3 mm <br />
<br />
A large-sized phenacolepadid limpet, Shinkailepas conspira is only known from deep-sea hydrothermal vents at Lau Basin in the southwestern Pacific where it inhabits surfaces of chimney structures and grazes on bacterial mats. Like all phenacolepadids it uses haemoglobin instead of haemocyanin as the oxygen-transporting protein and therefore when alive its soft parts are reddish. Though a common species in the narrow local habitat where it occurs, due to its extremely limited distribution at deep water vent fields it is rarely sampled. <br />
<br />
Typical shell length around 15 mm, very large specimens like the holotype shown here can exceed 20 mm. Its large size combined with the strong concentric ribs on the shell, an asymmetrical operculum, numerous paddle-like flaps on the epipodium, and hypertrophied oral and epipodial lobes together distinguishes it from other described Shinkailepas species. This species was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023.

Bathyacmaea nadinae Beck in Chen & Sigwart, 2023<br />
PECTINODONTIDAE<br />
Holotype (MNHN-IM-2000-38676)<br />
-1859 m, Hine Hina hydrothermal vent site (22°32'S 176°43'E), Lau Basin, Taken by the manned submersible HOV Nautile, BIOLAU cruise dive BL02, 1989/v/14, 23.0 mm <br />
<br />
With a restricted distribution in deep-sea hydrothermal vents of Lau and North Fiji Basins in the southwestern Pacific, Bathyacmaea nadinae is a large pectinodontid limpet inhabiting diffuse flow regions surrounding active smoker chimneys. Like other Bathyacmaea species, it is a grazing gastropod that feeds on microbial mats growing on various substrates in the hot vent environment, such as shells of bathymodioline mussels and chimney surfaces. Typical shell length around 15 mm, very large specimens can approach 25 mm. Unlike other Bathyacmaea species in the western Pacific which are often locally abundant where they occur, B. nadinae is a very rare species known from only about a dozen live-taken specimens plus some empty shells. <br />
<br />
This species was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023. This species was named in honour of Lothar Beck's daughter, Nadine Beck.

Lepetodrilus fijiensis Beck in Chen & Sigwart, 2023<br />
LEPETODRILIDAE<br />
Holotype (MNHN-IM-2000-38682)<br />
-1750 m, Vai Lili hydrothermal vent site (23°13'S 176°38'E), Lau Basin, Taken by the manned submersible HOV Nautile, BIOLAU cruise dive BL12, 1989/v/24, 11.0 mm <br />
<br />
A lepetodrilid vetigastropod limpet endemic to deep-sea hydrothermal vents, Lepetodrilus fijiensis is only known from Lau Basin (Vai Lili and Hine Hina vent fields) and North Fiji Basin (White Lady and Mussel Valley vent fields) in the southwest Pacific between 1700-2750 m deep. Living on hard substrates such as chimney surfaces and mussel shells, it is thought to combine filter-feeding and grazing on bacterial mats for nutrition like other Lepetodrilus limpets. A large-sized species for Lepetodrilus, the average shell length is about 8 mm while the largest known specimen is 12 mm. <br />
<br />
It is morphologically very similar to the sister species Lepetodrilus schrolli Beck, 1993 with a more western distribution in Manus Basin, southwest Pacific, but can be distinguished by having a much larger shell (L. schrolli averages around 3 mm and the largest known specimen is only 5.5 mm in shell length) with a more posterior apex, a radula with the central tooth having a longer cusp, and a deeper pallial cavity with shorter shell muscles. It is very abundant at the vent fields where it occurs, forming dense assemblages on hard substrata. Nevertheless, due to the extremely limited distribution at vent fields, it is rarely sampled. <br />
<br />
This species was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023.

Pyropelta ovalis Beck in Chen & Sigwart, 2023<br />
PYROPELTIDAE<br />
Paratype #2 (NSMT-Mo 79406)<br />
-2000 m, White Lady hydrothermal vent site (16°59'S 173°55'E), North Fiji Basin, Taken by the manned submersible HOV Nautile, STARMER II cruise dive PL21, 1989/vii/16, 5.5 mm <br />
<br />
Only known from two deep-sea hydrothermal vent fields in the southwestern Pacific (White Lady vent field, North Fiji Basin and Hine Hina vent field, Lau Basin), Pyropelta ovalis is a medium-sized pyropeltid limpet with an elongate, narrow, oval shaped shell. As typical for pyropeltid limpets inhabiting hydrothermal vents, the shell is usually heavily corroded on the dorsal surface, revealing a mesmerising pattern of irregular concentric lines represnting different degrees of corrosion at various parts of the shell. Pyropeltid limpets are considered to be grazers on bacterial mats growing on the hard substrates where they inhabit, and this species appears to be no exception. The handful of known specimens are little-varied with an average shell length just shy of 5 mm; the shown specimen is the largest one known at 5.5 mm. <br />
<br />
An elongate shell form for the genus combined with a radula with broad, rounded cusp on the central tooth and short, stiff denticles on the cusps of marginal teeth differentiates this species from other described Pyropelta species. It appears to be uncommon at the vent sites it inhabits, and this plus the great depth and rather small sizes of these sites means it is very rarely sampled. This species was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023.

Pseudorimula leisei Beck in Chen & Sigwart, 2023<br />
LEPETODRILIDAE<br />
Dorsal and lateral views: Holotype (MNHN-IM-2000-38680), 4.5 mm; Ventral view: Paratype 5 (SMF 370358), 2.7 mm <br />
-1853 m, Hine Hina hydrothermal vent site (22°32'S 176°43'E), Lau Basin, Taken by the manned submersible HOV Nautile, BIOLAU cruise dive BL03, 1989/v/15 <br />
<br />
A lepetodrilid "slit limpet" inhabiting deep-sea hydrothermal vents, Pseudorimula leisei is only known from the surface of sulfide 'chimneys' in active vent sites of North Fiji and Lau Basins, Southwestern Pacific. Due to the limpet shell form with a distinct slit, Pseudorimula was originally thought to be closely related to Fissurellidae. Later, however, molecular evidence showed that it was in fact more closely related to Lepetodrilus limpets which lack a slit but also typically inhabit chemosynthesis-based ecosystems like vents. There are only two other described Pseudorimula species, including P. marianae McLean, 1989 from the Mariana Trough, Southern Pacific and P. midatlantica McLean, 1992 from the Mid-Atlantic Ridge, Atlantic Ocean. In terms of shell morphology, P. leisei differs from both of these species in having a narrower shell with the apex positioned near to the posterior margin rather than central, and stronger radial ribs. The radular characters are also distinctive in that it has central and lateral teeth with coarse denticles and sharply pointed cusps. Though the exact diet of Pseudorimula species is unclear, they are most likely grazers that feed on bacterial mats. <br />
<br />
Typical shell length around 3 mm, very large specimens may exceed 5 mm. In larger specimens the shell surface is typically overlaid by a layer of sulfide mineral deposits which obscures the surface sculpture. Despite being locally common at the vent sites it inhabits, due to the very small size of these sites and the great depth it is very rarely sampled. It was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023. This species was named in honour of Dr Thorsten Leise, an entomologist who was a close friend of Beck when they both worked at Philipps-University of Marburg.

Symmetromphalus mcleani Beck in Chen & Sigwart, 2023<br />
NEOMPHALIDAE<br />
Holotype (MNHN-IM-2000-38688)<br />
-1842 m, Hine Hina hydrothermal vent site (22°32'S 176°43'E), Lau Basin, Taken by the manned submersible HOV Nautile, BIOLAU cruise dive BL01, 1989/v/13, 7.1 mm <br />
<br />
With the known distribution limited to deep-sea hydrothermal vents in North Fiji and Lau Basins in the southwestern Pacific, Symmetromphalus mcleani is a neomphalid snail characterised by up to 12 broad, radial ribs on the shell and a scaly periostracal margin which distinguishes it from the two described congeners. The periostracum is typically yellowish brown with a silky sheen. As typical for neomphalids it is a sexually dimorphic species, with the left cephalic tentacle being modified and enlarged into a penis in males; while in females both cephalic tentacles are of equal size. Like other congeners, it is thought to be a sessile filter-feeder based on its foot and gill morphology. Typical shell length around 5 mm, the largest specimen recorded so far is 8.9 mm. <br />
<br />
Despite being locally common at the vent sites it inhabits, due to the very small size of these sites and the great depth it is very rarely sampled. First collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, who drafted the description since at least 1997 but did not publishe it until he passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023. This species was named in honour of Dr James Hamilton McLean (1936-2016), who was the curator of Mollusca at the Natural History Museum of Los Angeles County and a renowned gastropod taxonomist.

Symmetriapelta wareni Beck in Chen & Sigwart, 2023<br />
PELTOSPIRIDAE<br />
Holotype (MNHN-IM-2000-38693)<br />
-2000 m, White Lady hydrothermal vent site (16°59'S 173°55'E), North Fiji Basin, Taken by the manned submersible HOV Nautile, STARMER II cruise dive PL12, 1989/vii/07, 4.1 mm <br />
<br />
Only known from deep-sea hot vents in North Fiji and Lau Basins (including the nearby northern Tonga-Tofau Volcanic Arc), Symmetriapelta wareni is a peltospirid characterised by a more-or-less symmetrical limpet-formed shell with scaly radial ribs. Though the vent-endemic Peltospiridae is known to be extremely variable in shell morphology among genera, this is the first limpet-shaped species with a central apex position and strong radial ribbing -- hence a new genus Symmetriapelta was named in order to house this species. The strength of ribs is very variable among individuals, and those with weaker ribs exhibit a larger number of them. However, across the whole range of rib strength the pattern of having one stronger rib followed by three to five weaker ones and another stronger rib, remains consistent. <br />
<br />
Despite being locally common at the vent sites it inhabits, due to the very small size of these sites and the great depth it is very rarely collected. It is considered to be a grazing gastropod feeding on bacteria growing on hard surfaces in vent fields. Typical shell length around 3.5 mm, very large specimens may exceed 5 mm. This species was first collected by French and Japanese joint expeditions in 1989 and studied by the German malacologist Lothar A. Beck, but the description remained unpublished until Beck passed away in 2020. Finally in 2022, Chong Chen and Julia Sigwart continued Beck's work based on his material and text, leading to its publication in 2023. This species is named after the eminent malacologist Anders Warén, curator emeritus in Swedish Museum of Natural History.

Lyria laseroni (Iredale, 1937)<br />
VOLUTIDAE<br />
Off Iluka, New South Wales, Australia, 29.2 mm <br />
<br />
Unmistakable with an unusually low spire and squat shell form for its genus, the "Laseron's Lyria" is a small volutid endemic to eastern Australia. Almost all specimens have been found in the northern half of the eastern coast of New South Wales, though there are scattered reports from more southern parts of the same state and it has also supposedly been recorded off Lord Howe Island. A very rarely seen species, almost all specimens have been collected as empty, beached shells and virtually no live-taken records are known. Occasional shells have been trawled up to about 50 m deep, and it probably inhabits sandy bottoms around this depth though this remains speculative. Though its diet is unknown, it is most likely a carnivorous and predatory gastropod feeding on invertebrate animals like other Lyria species. <br />
<br />
Early whorls carry about a dozen weak axial ribs, but these disappear in the body whorl which only carry fine spiral striae. Specimens vary considerably in colouration, ranging from pale tan to very dark brown; but how much of this is due to fading is unclear. Typical shell length around 25 mm, very large specimens may reach 35 mm. It was named in honour of Charles Francis Laseron (1887-1959), a malacologist and paleontologist who worked mostly in Sydney, Australia and described dozens of new species around the region. Its unusual shell form led to a new genus, Lyreneta, being established to house it at the time of description, though today this is recognised as a junior synonym of Lyria.

Babelomurex japonicus (Dunker, 1882)<br />
MURICIDAE<br />
-100 m, By tangle net, Bohol Island, Central Visayas, Philippines, 50.0 mm <br />
<br />
In contrast to its name, the "Japanese Latiaxis" is a coralliophiline muricid with a rather wide distribution range in the Pacific Ocean, from Japan to the Philippines to Hawaiian Islands, U.S.A. One of the most common latiaxis species, it is nevertheless one of the most attractive with a pure-white, intricately sculptured shell. Like all coralliophilines it lives in association with corals upon which it feeds by suctorial feeding. Majority of specimens are collected around 100 m deep, though its depth range is much broader between 50~400 m depth. <br />
<br />
The main source used to be deep-water gill nets and dredges in Japan, but with the advent of tangle nets in the Philippines that has become the most common source; trawls in East China Sea have also collected numerous specimens in the recent years. It is a rather variable species in terms of sculpture, especially the development of shoulder spines which can vary greatly in both length and breadth (and therefore frequency). Typical shell length around 35 mm, extremely large specimens may reach 60 mm. In Japan it is known by an elegant Japanese name,"Tennyo-no-Kamuri", meaning "Tiara of a Heavenly Maiden".

Bathybembix macdonaldi (Dall, 1890)<br />
CALLIOTROPIDAE<br />
-700 m, Trawled in nets for Royal Red Shrimp, Off Caldera, Atacama Region, Chile, 2006, 65.5 mm <br />
<br />
The magnificently sculptured "McDonald's Top" is a large calliotropid ranging between Pacific Panama and Chile. A deep-water species, it is a deposit-feeding gastropod inhabiting muddy bottoms between 200~1200 m deep; though most specimens are found between 500~1000 m deep. The holotype was collected off Manta, Ecuador in about 730 m depth by USFC Albatross. A very rarely seen species most likely due to the very deep depths it lives in, while in the natural habitat it is probably not uncommon. <br />
<br />
The shell always carries a strong spiral keel bearing numerous nodules on the periphery, while the more posterior keel near the suture is weaker and may or may not carry beads. The shell itself is pearly white, while the periostracum is greenish and has a silky sheen. Typical shell height around 60 mm, very large specimens may reach 80 mm. Originally described in the genus Turcicula, that genus is now considered a junior synonym of Lischkeia (in Turcicidae) and it was moved to Bathybembix in Calliotropidae. It was named after Colonel Marshall McDonald, who led the USFC Albatross expedition when the holotype was collected.

Fusilaria garciai Snyder, 2013<br />
FASCIOLARIIDAE<br />
-200 m, Taken in fish trap, Off Cabo Camarón, Gracias a Dios, Honduras, 183.2 mm <br />
<br />
A large and elegant fasciolariid so far only known from Honduras, the "García's Spindle" was so unusual that a new genus was described to house it. A unique feature among fasciolariids is that there are both interrupted and continuous lirae inside the outer lip, combined with the sharp columaellar folds which are usually two to three in number (though a few additional, much weaker ones may also be present). So far it appears to be a very rare species, with virtually all specimens have been collected as crabbed empty shells from traps set at about 200 m depth. No information is available on its diet, but it is presumably a carnivorous and predatory gastropod feeding on other invertebrate animal like other fasciolariids. Typical shell length around 160 mm, very large specimens may approach 200 mm. <br />
<br />
This species was first discovered by the American linguist and conchologist Emilio Fabian García of Lafayette, Louisiana who has described many new species of gastropods especially from Gulf of Mexico and Caribbean Sea. García collected the type series from a lobster trap off Honduras, which were all crabbed, and donated two specimens to Academ of Natural Sciences of Drexel University, Philadelphia, U.S.A.; this species was thus named in his honour.

Sveltia centrota (Dall, 1896)<br />
CANCELLARIIDAE<br />
-120 m (-400 ft.), Dredged, Off northwest of Isla Danzante, Gulf of California, Mexico, 1970's, 24.3 mm <br />
<br />
Characterised by a single row of long spines on the shoulder, the "Spiny Nutmeg" is a unique cancellariid ranging from Mexico to Pacific Panama with records also from the Galápagos Islands, Ecuador; the type locality is Cocos Island, Costa Rica. Each whorl typically bears 8-10 more or less evenly spaced varices with sharp, slightly recurved spines. It is a rarely seen species, usually trawled or dredged from around 100-200 m deep on soft bottoms. Though its diet is unknown, it is likely a suctorial feeder on the body fluid of other animals like most cancellariids. Typical shell length aroud 25 mm, very large specimens may reach 35 mm. <br />
<br />
It is most similar to Sveltia gladiator (Petit, 1976) from the Galápagos Islands, but can be differentiated as S. gladiator is much larger (typical shell length 45 mm and reaching 55 mm) and also exhibits multiple spines on each varix. The shell of S. gladiator is semi-transparent and less solid than that of S. centrota. Other similar species include Sveltia yoyottei Petit & Harasewych, 2011 from around Guadeloupe which has much shorter spines and also smaller shells (typical shell length 10 mm, large specimens reach 15 mm); and Sveltia lyrata (Brocchi, 1814) from off western Africa which has a much taller spire and shorter spines.

Conus dusaveli (Adams, 1872)<br />
CONIDAE<br />
-80~100 m, By tangle net, Tinina, Balut Island, Davao Occidental, Philippines, 74.2 mm <br />
<br />
The "Du Savel's Cone" is an extremely illustrous classic rarity among the conids, with an intriguing history. The holotype was owned by a Mr Du Savel, its namesake, when it was described in 1872 and supposedly came ex pisces (i.e. from the stomach of a fish) off Mauritius. It remained elusive and one of the greatest rarity among cones as no other specimen was found, and the holotype exchanged hands several times for high prices. Unsurprisingly it made into S. Peter Dance's 50 "Rare Shells" (1969), but shortly after that in 1972 two cone shells dredged off Okinawa, Japan in the National Museum of Tokyo was revealed to be this species. Then the first dive collected specimens were collected also in Okinawa in the late 1970s, and by end of the 1980s specimens began turning up from the deep-water tangle nets of Philippines. Today it is only uncommon, and its distribution centre is from Philippines to Okinawa, Japan; although records also exist from as far as New Caledonia. The holotype which was unique for exactly 100 years after description, and currently resides in the Melvill-Tomlin Collection in the National Museum of Wales; the orignially stated type locality of Mauritius is likely erroneous. It is a carnivorous gastropod that hunts fish by injecting poison with its toxoglossate radula, and inhabits sandy bottoms of moderate depths around -50~250 m deep. Very variable in colouration and pattern and less so in form; typical shell length around 75 mm but very large specimens can exceed 90 mm.

Homalocantha dovpeledi Houart, 1982<br />
MURICIDAE<br />
-30 m, SCUBA dived, Taken on coral covered by sea anemones, Red Sea, Eilat, Israel, 2005/viii, 53.6 mm <br />
<br />
Endemic to the Red Sea, the "Dov Peled's Murex" is characterised by a brownish shell with flat spines that bifurcate at the distal end. A rarely seen species, likely partly due to its restricted distribution and the fact that the shell is usually completely overgrown, making it very challenging to spot. The shell is easily recognisable but specimens do vary considerably in terms of the colouration and spine development. Vast majority of shells are orange-tan in colour, though they can range from whitish to very dark brown. A carnivorous and predatory species feeding on other invertebrate animals, it inhabits hard bottoms around reefs in shallow depths betweeen about -10~50 m. Typical shell length around 50 mm, very large specimens may reach 65 mm. It was named after Dov Peled of Tivon, Israel, who was a prominent shell collector and dealer for Red Sea species. Peled collected the type material for a number of species between eastern Africa and Red Sea, and as a result a few species including this one were named after him.

Buccinum clarki (Kantor & Harasewych, 1998)<br />
BUCCINIDAE<br />
-205 m, Trawled on black sand, North of Atka Island, Alaska, U.S.A., Leg. Roger Clark, 1997/vii, 55.4 mm <br />
<br />
The "Clark's Whelk" is a bathyal buccinid endemic to the Aleutian Islands, where it inhabits soft bottoms between about 150~500 m deep. The shell is ornamented by numerous fine spiral cords and lacks prominent axial sculpture; the operculum is unusual in being small, triangular, and having a subcentral nucleus. This operculum morphology, together with it having a very large osphradium, led to its original description in genus Bathybuccinum. However, a recent phylogenetic study synonymised Bathybuccinum with Buccinum, and therefore it is now placed in that genus. A carnivorous and predatory gastropod, it presumably feeds on other invertebrate animals. Its restricted range in the Aleutian Islands means it is a rather rarely seen species. Typical shell length around 45 mm, very large specimens may exceed 65 mm. Young specimens tend to exhibit stronger peripheral keels on the shell, which becomes much weaker on the body whorl of larger specimens. The species name was dedicated to the American conchologist Roger N. Clark who participated in many surveys around the Aleutian Islands and collected the type material.

Halicardia flexuosa (Verrill & Smith, 1881)<br />
VERTICORDIIDAE<br />
-1000 m, Trawled, Off Namibia, 48.0 mm <br />
<br />
A deep-sea bivalve with very unusual shell morphology characterised by strong 'folds', the "Flexed Verticord" is a large verticordiid with a very wide distribution throughout the Atlantic Ocean. Published records indicate scattered specimens have been collected from localities spanning off Massachusetts, U.S.A. (type locality) to Iceland to Scotland to Bay of Biscay to Namibia to even the western coast of South Africa. These records tally up to only about 10 live-taken specimens and a few dozens of dead and disarticulated single valves, making it an extremely rare species. Live individuals have been taken from deep waters between approximately -500~2000 m, whereas empty valves have been collected from a wider bathymetric range between about -200~2500 m. <br />
<br />
The shell always carries three major 'folds', the median one by far the strongest; this is a unique feature that separates this species from other named congeners. The overall development of these cords vary from specimen to specimen and influences the overall shell form, where those with stronger cords exhibit a higher shell shape with more angular margins. As in other Halicardia species, numerous fine radial striae are also present on the shell but do not influence the overall shell form. A carnivorous bivalve, it captures small prey (mainly crustaceans) using a strong suction current enabled by anatomical adaptations such as the gills being modified into mucsular septa. Verticordiids are also capable of using adhesive fluid on the siphons to help capture prey, and have evolved muscular oesophagus and muscular stomach to crush them. <br />
<br />
Typical shell height around 30 mm, very large specimens can exceed 45 mm. It is the type species of the genus Halicardia, the name of which refers to the shell form that appears to be heart-shaped when viewed from the side. The specific epithet 'flexuosa' was named in reference to the three folds, or 'flexes' on the shell surface.

Lotoria armata (Sowerby III, 1897)<br />
CYMATIIDAE<br />
Dived in shallow water, Northern Queensland, Australia, 64.0 mm <br />
<br />
Characterised by a spiny shell with numerous short spines on the varices and very strong intervarical nodes, the highly distinctive "Armed Triton" is perhaps the rarest and most sought-after cymatiid of all. This species was made famous when it was rediscovered by Russ Webb of the Oregon Shell Club who found a live specimen in Fiji in 1996 and then posted photos on the (online) Hawaiian Shell News for identification in 1997. Other collectors including Harry G. Lee and Betty Jean Piech correctly identified the species, and followed up with comments noting that only seven specimens were known at the time and that it took exactly a century since description for a specimen to be collected with detailed collecting data. Even today it is only known from not much more than a couple dozens of specimens despite inhabiting shallow waters from just a couple of meters down to about 20 m deep, the reasons behind its rarity is unclear. <br />
<br />
The holotype was a specimen with unknown locality, though Sowerby III speculated that it might have come from the Marquesas Islands since its collector B.C. Thomas had collected most of his material in French Polynesia. All later specimens collected with reliable data, however, were from an area of the South Pacific much further to the west including Vanuatu, New Caledonia, Fiji, and Queensland of Australia; indicating Sowerby III's speculation was likely incorrect. Live specimens have been collected on top of coral reefs or on rocky slopes near reefs, and at least one has been found beached after storm. It is presumably a carnivorous and predatory gastropod feeding on other invertebrate animals like typical cymatiids. Though always instantly recognisable, it is quite variable in the extent of spine development and also the base colour of the shell can range from light brown to dark red. Typical shell length around 60 mm, the largest specimens can exceed 80 mm. Originally described in Lotorium (now synonym of Cymatium), it was once moved to Ranularia based on its long anterior siphonal canal but later transferred to Lotoria largely on the basis of having an operculum with an antetior terminal nucleus rather than a subcentral one typical of Ranularia.

Galeodea maccamleyi Ponder, 1983<br />
CASSIDAE<br />
-50~100 m, Off Cape Moreton, Queensland, Australia, 34.1 mm <br />
<br />
An unusually small species for its genus with a typical shell length around 30 mm and the largest specimens reaching only 40 mm, the "McCamley's Bonnet" is a cassid endemic to southern Queensland, Australia, ranging approximately between Swain Reefs and the Capricorn Channel. Its prickly shell is characterised by four evenly spaced spiral rows of whitish nodules on a pale or darkish brown background, as well as a dark protoconch (most Galeodea species have white protoconchs). Furthermore, the fine but strong, numerous spiral threads distributed across the entire shell surface even on the early teleoconch whorls also help separate it from other congeners. <br />
<br />
A carnivorous gastropod presumably feeding on echinoderms like other cassids, it inhabits soft bottoms of moderate depths between about -100~400 m deep. It is a rare species, majority of specimens have been collected dead as empty shells; live-taken specimens retaining a striking colour pattern are seldom seen. The first known specimens were collected by the Queensland shell collectors F. McCamley and Jim Whittle who provided the material to the Australian Museum for study and description. It was named after McCamley, who donated the holotype specimen plus two paratypes to the museum upon the description of this species.

Volutoconus bednalli (Brazier, 1878) <br />
VOLUTIDAE<br />
-450m, Trawled on sandy reef in the Arafura Sea, Off Indonesia, 1995, 148.2 mm <br />
<br />
The "Bednall's Volute" is a classic rarity among the volutes and one of the most striking species characterised by a shell with a unique and extremely attractive chocolate-laced pattern. One of S. Peter Dance's 50 "Rare Shells" (1969); it was described from a shell that belonged to the Australian collector William T. Bednall, its namesake. This shell remained the sole known specimen until 1893, and by early 1900s more specimens had appeared. An anecdote tells that divers used to exchange each specimen caught with a bottle of brandy. <br />
<br />
Today it is known to be a moderately rare species ranging from northern Australia (in the Arafura Sea and the Timor Sea) to eastern Indonesia. It is a predatory gastropod inhabiting shallow to moderately deep water around -50~150m deep, and usually lives on sandy bottoms. Typical shell length around 110 mm, although extreme giants may exceed 165 mm. The spire height varies greatly and accounts for much of the size variation. The extent of surface sculpture on the shell may also vary from rather smooth to strong and wrinkle-like; and the base colouration ranges between pure white and yellowish white.

Eofavartia tatei (Verco, 1895)<br />
MURICIDAE<br />
-38 m, Dived, Among seaweed on coarse sand, Off Cape Le Grand, Esperance, Western Australia, Australia, 1999, 29.4 mm <br />
<br />
An unmistakable muricid with a multifaceted-looking shell, the "Tate's Murex" is endemic to the south coast of Australia and ranging roughly between Esperance, Western Australia and Backstairs Passage, South Australia. Originally described in the genus Murex, it was later moved to Murexiella (now synonymised with Favartia) where it stayed for decades. In 2013 it was transferred again to Subpterynotus based on fine details of the varical ornamentation, despite typical Subpterynotus species were only known from fossils outside the Indo-West Pacific all having three varices per whorl. Recently in 2020, it was instead attributed to Eofavartia as a relict species of that genus which is also known from Pliocene fossils in Australia, noting that it lacks two key characters of Subpterynotus -- trivaricate shell and intervarical ribs. Currently it is considered to be the only extant species of the genus whose fossil record extends back to Palaeogene. <br />
<br />
A carnivorous and predatory gastropod probably feeding on other invertebrate animals, it inhabits rather shallow waters between 20~50 m deep and is a rarely seen species. Though it cannot be confused with other living muricids it is somewhat variable in the development of the final varix, and the shell colouration can range between whitish to dark brown. Typical shell length around 25 mm, very large specimens may exceed 35 mm. It was named in honour of Ralph Tate (1840-1901), who worked as a professor of geology at the University of Adelaide but also made significant contributions to both invertebrate paleontology and botany.

Pyrulofusus deformis (Reeve, 1847)<br />
BUCCINIDAE<br />
-150~250 m, Trawled, Bristol Bay, Bering Sea, Alaska, U.S.A., 1978/viii, 98.5 mm <br />
<br />
The "Sinistral Arctic Whelk" is a cold-water buccinid whelk notable for producing a normally sinistral shell. Though perhaps best known from Sea of Okhotsk and Bering Sea, its distribution extends to the Arctic Ocean where it has a nearly circumpolar range -- the type locality is actually Spitsbergen in northern Norway. A carnivorous gastropod, it inhabits a wide-range of substrates from rocky to muddy to sandy bottoms and across a rather broad bathymetric range between about 10~300 m deep. Like other Pyrulofusus species it goes through direct development and hatches as crawling juveniles over 1.5 cm in shell length, from large eggs about 2.5 cm in diameter. An egg collected from Alaska was found to contain three hatchlings, almost completely filling up the available space. Though supposedly not uncommon in its natural habitat, the limited availability of material from its range makes it a moderately rarely seen species. Typical shell length around 100 mm but this is greatly variable, with mature specimens ranging between around 50~150 mm. Both the shell surface colouration and the colour inside the aperture are rather variable, from whitish yellow to dark chestnut to even reddish violet. <br />
<br />
It is often confused with its another sinistral species in the same genus, the rarer Pyrulofusus harpa (Mörch, 1858). The two species are actually not difficult to distinguish, as P. harpa carries coarse, regular, strongly raised spiral cords across the entire shell that is lacking in P. deformis. Furthermore, P. harpa has a much narrower distribution range, being only found off Alaska including the Aleutian Islands. Though there are some records of supposedly P. harpa from Sea of Okhotsk to off Kamchatka Peninsula, extensive research samplings have not recovered a single specimen reliably localised in this area and these records therefore most likely represent misidentified specimens of P. deformis.

Priotrochatella constellata (Morelet, 1847)<br />
HELICINIDAE<br />
On limestone, Sierra de Casas, Isla de la Juventud (Isle of Pines), Cuba, 1994/ix, 12.6 mm<br />
<br />
Endemic to Sierra de Casas, a mountain range on Isla de la Juventud (also known as Isle of Pines) of Cuba, Priotrochatella constellata is among the world's most eye-catching landsnails characterised by numerous delicate blade-like varices on a strongly carinated shell with an offset coiling in the last two whorls. The base shell colouration is white to very light yellow, overlaid by patches of darker colour that can range from yellow to strawberry red. These patches are distributed rather regularly on earlier whorls, but become increasingly sparse and irregular on the later ones. The shell is otherwise little-varied among individuals; in fully mature individuals the lip is thickened. Typical shell width around 10 mm, very large specimens may approach 15 mm. As is typical in helicinids it possesses a kidney-shaped operculum, which is thinly calcified with a papillose surface. <br />
<br />
A herbivorous grazer, it lives on limestone and feeds on the algae and lichens that grow on the same rocks. Though supposedly common in its local habitat, due to its restricted range in a politically difficult area it is a rarely collected species. In the recent years, it has become increasingly threatened by quarrying activities in and near its habitat. The genus Priotrochatella itself is restricted to Isla de la Juventu, Cuba and Jamaica; among all three known species P. constellata exhibits the most elaboratly ornamented shell. The coiling offset seen in the penultimate and final whorl in P. constellata is unique in Priotrochatella, and hence it cannot be confused with other species.

Callipara bullatiana Weaver & duPont, 1967<br />
VOLUTIDAE<br />
-20 m, Dived on sand, Algoa Bay, Cape Province, South Africa, 1995, 55.2 mm <br />
<br />
The "Bullate Volute" is a uniquely shaped volutid endemic to South Africa, instantly recognisable from its short-spired, cylindrical shell lackin in shoulder nodules. Ranging from central Algulhas Bank to around Port Elizabeth, it inhabits shallow to moderate depths between around -10~50 m and is a carnivorous gastropod mainly feeding on other invertebrate animals. <br />
<br />
Initially, it was described as Voluta bullata Swainson, 1829 which was unfortunately a junior homonym of Voluta bullata Born, 1778 (now Bullata bullata (Born, 1778), a brazilian marginellid) which led to the replacement name Callipara bullatiana Weaver & du Pont, 1967. The genus Callipara was originally established to house just this species due to its strange shell shape, but later it became clear that the soft parts of this species is in fact very similar to other African volutids such as Callipara africana (Reeve, 1856) which were then housed in Festilyria. The shell structure and colouration are also in fact similar to C. africana, currently thought to be its closest living relative. As a result, Festilyria was synonymised with Callipara and all species in that genus were moved to Callipara. The reason behind C. bullatiana evolving an unusual shell shape, resembling and often compared with the Australian enigma Lyria laseroni (Iredale, 1937), which is very different from all of its congeners, remains unclear. <br />
<br />
Though clearly not a rare species in its natural environment due to beached empty shells being quite common, live animals have been surprisingly scarcely seen by divers and live-taken specimens remain rare. Generally stable in shell morphology with individuals usually differing only in the development of the shell pattern, though it is quite variable in size. The average shell length of mature specimens is around 55 mm, but the extremes can be as small as 40 mm and as large as 80 mm.

Tonna hawaiiensis Vos, 2007<br />
TONNIDAE<br />
-200~250 m, By lobster trap, Off Oahu, Hawaii, U.S.A., 1980/vi, 139.2 mm <br />
<br />
As its name suggests, the "Hawaiian Black-Mouthed Tun" is a tonnid endemic to the Hawaiian Islands where it is known from a rather wide bathymetric range from about -5~200 m deep. Although locally common when taking into account crabbed and beached shells, live-taken specimens are rare; it appears to be more common in the Leeward Islands than the Windward Islands. The live animal is entirely black in colouration, and is presumably an active carnivorous and predatory gastropod feeding on echinoderms. Due to the remarkable blackish colouration around the aperture it has been long confused with Tonna melanostoma (Jay, 1839) from the Western Pacific, the only other species in the genus Tonna that shares this characteristic, with the Hawaiian specimens considered a form of T. melanostoma. <br />
<br />
At last, after examining many specimens of both species carefully side-by-side, the tonnid expert Chris Vos was able to show clearly that the two are separate species which led to the description of T. hawaiiensis. The two species differ most clearly in the spiral sculpture, with T. hawaiiensis having rounded, crested, and raised cords similar to T. variegata (Lamarck, 1822) and most interspaces lack obvious secondary cords, whereas T. melanostoma has broad, flat main cords with well-defined secondary cords between them, reminiscent of T. chinensis (Dillwyn, 1817). Although T. hawaiiensis appears to be greatly variable in size with a typical shell length around 100 mm but the largest specimen confirmed exceeds 200 mm, generally speaking it is smaller and more elongate in shell form than T. melanostoma (typical shell length around 200 mm, largest specimens exceed 300 mm). Even in the largest specimens of T. hawaiiensis the inside of the aperture is not fully darkened like that of adult T. melanostoma shells. Often the shell of T. hawaiiensis carry a pattern with randomly placed white patches, which is lacking in T. melanostoma. In young T. melanostoma the colouration of the main cords usually alternate between whitish and brownish (a feature lost in adults), but this is not seen in T. hawaiiensis of a similar size.

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