Tag: Mollusca

The first cave-bound mollusc species from the Americas

Against the odds, a study by Brazilian researchers describes a new to science species of evidently cave-bound – or troglobitic – clam from northern Brazil.

Exclusively subterranean bivalves – the group of molluscs comprising clams, oysters, mussels, scallops – are considered a rarity. Prior to the present study, there had only been three such species confirmed in the world: all belonging to a small-sized mussel genus known from southeastern Europe. Furthermore, bivalves are not your typical ‘underworld’ dweller, since they are almost immobile and do not tolerate environments low in oxygen.

Against the odds, a recent study by Dr. Luiz Ricardo L. Simone (Museum of Zoology of the University of São Paulo) and Dr Rodrigo Lopes Ferreira (Federal University of Lavras), published in the open-access scholarly journal Subterranean Biology, describes a new to science species of evidently cave-bound – or troglobitic – clam from northern Brazil.

Small individuals of the newly described clam species Eupera troglobia sp. n. exposed to the air, next to a harvestman (Eusarcus sp.). Photo by Rodrigo Lopes Ferreira.

Named Eupera troglobia, the mollusk demonstrates features characteristic for organisms not meant to see the daylight, including lack of pigmentation, reduced size, delicate shell and fewer, yet larger eggs.

Curiously, it was back in 2006 when a report presenting a faunal survey of a cave in northern Brazil featured photographs of what was to be described as Eupera troglobia. However, the evidence was quickly dismissed: the clam must have been carried into the cave by water.

A submerged specimen of the newly described cave-bound clam species Eupera troglobia sp. n.

In 2010, Dr Rodrigo Lopes Ferreira accessed the report and noticed the depigmentation of the clams. Wondering whether it was indeed possible that he was looking at a troglobite, he searched amongst the collected specimens from that study, but could not find any of the discoloured bivalve.

Ten years later, his team visited the cave to specifically search for depigmented shells. Although the cave was partially flooded, the researchers were able to spot the specimens they needed attached to the walls of the cave.

In conclusion, the scientists highlight that their discovery is the latest reminder about how important the conservation of the fragile subterranean habitats is, given the treasure troves in their holdings.

Meanwhile, recently amended laws in Brazil put caves at considerably higher risk.

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Research paper:

Simone LRL, Ferreira RL (2022) Eupera troglobia sp. nov.: the first troglobitic bivalve from the Americas (Mollusca, Bivalvia, Sphaeriidae). Subterranean Biology 42: 165-184. https://doi.org/10.3897/subtbiol.42.78074

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Novak Djokovic now has a tiny new snail species named after him

Do freshwater snails make good tennis players? One of them certainly has the name for it.

Enter Travunijana djokovici, a new species of aquatic snail named after famous Serbian tennis player Novak Djokovic.

Photo of Tavunijana djokovici, a new snail species from Montenegro named after Serbian tennis player Novak Djokovic. Photo by J. Grego

Slovak biospeleologist Jozef Grego and Montenegrin zoologist Vladimir Pešić of the University of Montenegro discovered the new snail in a karstic spring near Podgorica, the capital of Montenegro, during a field trip in April 2019. Their scientific article, published in the open-access, peer-reviewed journal Subterranean Biology, says they named it after Djokovic “to acknowledge his inspiring enthusiasm and energy.”

“To discover some of the world’s rarest animals that inhabit the unique underground habitats of the Dinaric karst, to reach inaccessible cave and spring habitats and for the restless work during processing of the collected material, you need Novak’s energy and enthusiasm,” the researchers explain.

T. djokovici has a milky-white shell in the shape of an elongated cone and is adapted to live in the underground habitats of the Dinaric karst. It is part of Hydrobiidae, a very diverse family of small to tiny snails – also known as mud snails – inhabiting fresh or brackish water, including caves and subterranean habitats.

The type locality where Tavunijana djokovici was found.

This is the first member of the genus Travunijana so far to be discovered in the Skadar Lake basin, and the only one found outside of the Trebišnjica river basin in Herzegovina, which points to the enigmatic distributional range of these snails across the Dinaric underground habitats. Where they came from, and how, remains a mystery.

Because of its small area of occupancy, T. djokovici is assessed as Vulnerable, according to the IUCN Red List of Threatened Species. Subterranean ecosystems, the authors of the new species emphasise, are extremely vulnerable to human-driven environmental changes, and, being obscure, they’re often overlooked during conservation efforts.

Original source:

Grego J, Pešić V (2021) First record of stygobiotic gastropod genus Travunijana Grego & Glöer, 2019 (Mollusca, Hydrobiidae) from Montenegro. Subterranean Biology 38: 65–76. https://doi.org/10.3897/subtbiol.38.64762

Tiny thorn snail discovered in Panama’s backyard

*Close-up view of live individuals of the new species crawling on a leaf.*

Discoveries of biodiversity at the Lilliputian scale are more tedious than it is for larger animals like elephants, for example. Furthermore, an analysis producing a DNA barcode – a taxonomic method using a short snippet of an organism’s DNA – is not enough to adequately identify it to the species level.

In the case of tiny thorn snails – appearing as minute white flecks grazing in moist, decomposing leaf litter – it is the shell that provides additional and reliable information needed to verify or question molecular assessment of these otherwise, nondescript critters.

*Broadleaf forest litter with white arrows indicating the newly described species on the leaves.*

However, at 2 mm, thorn snails are too small and fragile to handle and the few, if any, tangible details on the outside of the shells can only be seen using a high-powered microscope and computed tomographic (CT) images.

This is exactly how the interdisciplinary team of Dr Adrienne Jochum, Naturhistorisches Museum der Burgergemeinde Bern (NMBE) and University of Bern, Dr. Bernhard Ruthensteiner, Zoologische Staatssammlung Muenchen, Germany, Dr. Marian Kampschulte, University Hospital of Giessen and Marburg, Gunhild Martels, Justus-Liebig University Giessen, Jeannette Kneubühler, NMBE and University of Bern, and Dr. Adrien Favre, Senckenberg Research Institute and Natural History Museum Frankfurt, managed to clarify the identity of a new Panamanian species. Their study is published in the open-access journal ZooKeys.

Even though the molecular analysis flagged what it was later to be named as the new to science species, Carychium panamaense, the examination left no shell for the description of the new snail to be completed, let alone to serve as tangible, voucher material in a museum collection available to future researchers. The mini forest compost-grazer had to wait for another five years and Dr. A. Favre, who collected fresh material while traveling in Panama.

The new snail is currently the second member of the family Carychiidae to be discovered in Panama. The first Panamanian, and southern-most member of its kind in the Western Hemisphere, is C. zarzaae, which was also described by Dr. A. Jochum and her team along with two sister species from North and Central America. The study was published in ZooKeys last year.

Much like X-rays showing the degree of damage in a broken bone, CT images visualise the degree of sinuosity of the potato chip-like wedge (lamella) along the spindle-like mast (columella) inside the thorn snail’s shell. These structures provide stability and surface area on which the snail exerts muscular traction while manoeuvring the unwieldy and pointed, signature thorn-like shell into tight nooks and crannies. The alignment and degree of waviness of the lamella on the columella is also used by malacologists (mollusc specialists) to differentiate the species.

*These are computed tomographic (CT) images of the new thorn snail species.*

Normally, a study of a thorn snail’s shell would require drilling out minute ‘windows’ in the shell by using a fine needle under a high microscope magnification.

“This miserable method requires much patience and dexterity and all too often, the shell springs open into oblivion or disintegrates into dust under pressure,” explains Dr. A. Jochum. “By exposing the delicate lamella using non-manipulative CT imaging, valuable shell material is conserved and unknown diversity in thorn snails becomes widely accessible for further study and subsequent conservation measures.”

The authors are hopeful that C. panamaense and C. zarzaae, which both inhabit the La Amistad International Park, Chiriquí, will remain a conservation priority along with other animalian treasures including the Resplendent Quetzal, Three-Wattled Bellbird and the Crested Eagles.

The park is considered the 1st bi-national biosphere reserve, as it occupies land in both Costa Rica and Panama, and constitutes a UNESCO World Heritage Site since 1990.

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Original Source:

Jochum A, Ruthensteiner B, Kampschulte M, Martels G, Kneubühler J, Favre A (2018) Fulfilling the taxonomic consequence after DNA Barcoding: Carychium panamaense sp. n. (Eupulmonata, Ellobioidea, Carychiidae) from Panama is described using computed tomographic (CT) imaging. ZooKeys 795: 1-12. https://doi.org/10.3897/zookeys.795.29339

New ‘scaly’ snails species group following striking discoveries from Malaysian Borneo

Six new species of unique land snails whose shells are covered with what look like scales have been described from the biodiversity hotspot of Malaysian Borneo by scientists Mohd Zacaery Khalik, Universiti Malaysia Sarawak, Kasper Hendriks, University of Groningen, Jaap Vermeulen, JK Art & Science, and Prof Menno Schilthuizen, Naturalis Biodiversity Center. Their paper is published in the open access journal ZooKeys.

Thanks to their conspicuous structures, the mollusks have been added to a brand new species group of land snails to be commonly known as the ‘scaly’ snails, so that they can be set apart from the rest in the genus Georissa. Why it is that only some of the species in the genus sport the unique ‘scales’, remains unknown.

Fascinated with the minute ‘scaly’ snail fauna of Borneo, the researchers carried out fieldwork between 2015 and 2017 to find out how these curious shells evolved. In addition, they also examined material deposited in museum and private snail collections.

Apart from DNA data, which is nowadays commonly used in species identification, the team turned to yet-to-become-popular modern tools such as 3D modelling, conducted through X-ray scanning. By doing so, the researchers managed to look at both the inner and outer surfaces of the shells of the tiny specimens from every angle and position, and examine them in great detail.

The researchers note that to identify the ‘scaly’ snails to species level, one needs a combination of both DNA and morphological data:

“Objective species delimitation based solely on molecular data will not be successful for the ‘scaly’ snails in Georissa, at least if one wishes for the taxonomy to reflect morphology as well.”

The six new species are all named after the localities they have been originally collected from, in order to create awareness for species and habitat conservation.

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Watch rotation and cross-section of the 3D models of the studied species here.

Original source:

Khalik MZ, Hendriks K, Vermeulen JJ, Schilthuizen M (2018) A molecular and conchological dissection of the “scaly” Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae). ZooKeys 773: 1-55. https://doi.org/10.3897/zookeys.773.24878

DNA study in the Pacific reveals 2000% increase in our knowledge of mollusc biodiversity

Lead author Dr Helena Wiklund examining specimens on the RV Melville in October 2013

Scientists working in the new frontier for deep-sea mining have revealed a remarkable 2000% increase in our knowledge of the biodiversity of seafloor molluscs.

The 21 mollusc species newly described thanks to the latest DNA-taxonomy methodology

Tweny-one species, where only one was previously known, are reported as a result of the research which applied the latest DNA-taxonomy methodology to mollusc specimens collected from the central Pacific Clarion Clipperton Zone (CCZ) in 2013. They are all described in the open access journal ZooKeys.

Among the discoveries is a monoplacophoran mollusc species regarded as a ‘living fossil’, since it is one the ancestors of all molluscs. This is the first DNA to be collected from this species and the first record of it from the CCZ mining exploration zone – a vast 5-million-km² region of the central Pacific that is regulated for seabed mining by the International Seabed Authority.

“Despite over 100 survey expeditions to the region over 40 years of mineral prospecting, there has been almost no taxonomy done on the molluscs from this area,” says lead author Dr Helena Wiklund of the The Natural History Museum in London (NHM).

Dr Wiklund undertook a comprehensive DNA-based study of the molluscs to confirm species identities and make data available for future taxonomic study. This was coupled with the expertise of the NHM’s Dr John Taylor, who led the morphological work.

The molluscs were found in samples taken on and in the mud surrounding the potato-sized polymetallic nodules that are present in high abundance across the CCZ. These nodules are the target for potential deep-sea mining being rich in cobalt, copper, nickel, manganese and other valuable minerals.

The data are vital for the future environmental regulation of deep-sea mining, but have also revealed surprising patterns.

“I was amazed to discover that specimens collected during the 19th century by HMS Challenger were probably the same as ours over a range of 7000 km, but that data lodged on genetic databases from closer but shallower depths is likely to be from a different species,” comments Dr Thomas Dahlgren, population geneticist at Uni Research, Norway and University of Gothenburg, Sweden, who studied in detail a species called Nucula profundorum.

“Our efforts are now focussing on studying the DNA from many more samples of this species to examine connectivity and potential resilience to deep-sea mining,” he added.

Dr Thomas Dahlgren sieving sediments to find new clam and snail species

“It is a simple truth that we cannot move forward on regulatory approval for deep-sea mining without fundamental baseline data on what animals actually live in these regions,” says Principal Investigator of the NHM Deep-sea Systematics and Ecology Research Group, Dr Adrian Glover.

“Our work has highlighted obvious gaps in our knowledge, but also shown that with even relatively modest effort, we can greatly increase our understanding of baseline biodiversity using DNA-taxonomy.”

Creating a library of archived DNA-sequenced samples from known species allows for the future possibility of using the latest environmental DNA (eDNA) methods to ‘search’ for these species using just tiny samples of mud or seawater.

“Its akin to forensic science’, says Dr Glover. “You can’t use eDNA to find the criminals or species unless you have a library of information to compare them too”.

All data and specimens from the study have been lodged at the NHM and online repositories to make them accessible for future study. Of particular importance are the frozen tissue collections, which are housed in the state-of-the-art Molecular Collections Facility at the NHM and available for loan or further DNA work.

Original source:

Wiklund H, Taylor JD, Dahlgren TG, Todt C, Ikebe C, Rabone M, Glover AG (2017) Abyssal fauna of the UK-1 polymetallic nodule exploration area, Clarion-Clipperton Zone, central Pacific Ocean: Mollusca. ZooKeys 707: 1–46. https://doi.org/10.3897/zookeys.707.13042

Three new mini thorn snails described from Georgia (USA), Belize and Panama

Although computer tomography (CT) is widely used in medicine, its application in micro snail identification is still at the pioneering stage.

However, Dr Adrienne Jochum from the Naturhistorisches Museum der Burgergemeinde Bern (NMBE), Switzerland and her interdisciplinary team of German and Swiss scientists (Dr. Alexander M. Weigand, University of Duisburg-Essen, Estee Bochud and Thomas Inäbnit, NMBE and the University of Bern, Dorian D. Dörge, Goethe University, Frankfurt, Dr. Bernhard Ruthensteiner, Zoologische Staatssammlung Muenchen, Dr. Adrien Favre, Leipzig University, Gunhild Martels and Dr. Marian Kampschulte, Justus-Liebig University Giessen) have recently applied it in their research, now published in the journal ZooKeys.

As a result of their revolutionary approach, the scientists report three new thorn snail species – tiny, colourless and highly fragile creatures that measure less than 2 mm and belong to the genus Carychium.

Much like X-rays showing the degree of damage in broken bones, CT scans provide access to snail shells. Differences, such as the degree of sinuosity of the potato chip-like wedge (lamella), elegantly gliding along the spindle-like columella, become visible. These structures provide stability and surface area to exert muscular traction while manoeuvring the unwieldy shell into tight cavities. The alignment and degree of undulation of the lamella on the columella is also used by malacologists (mollusc specialists) to identify different thorn snail species.

Conventionally, examination of this signatory character requires cutting a hole in the shell with a fine needle under the microscope. This tedious method requires a much patience and dexterity and, all too often, the shell cracks open or disintegrates into dust under pressure. By exposing the delicate lamella to non-manipulative CT scans, Dr. Jochum and her team have found the best method to differentiate not only thorn snails but also many other micro creatures.

Together with G. Martels and Dr. M. Kampschulte, Dr. Jochum described new micro snails for the first time using CT in East Asian hypselostomatid snails in 2014. The first subterranean Asian relative of the thorn snails (Koreozospeum nodongense), was also described by Dr. Jochum thanks to CT scans in 2015.

The scientists studied and compared thorn snails collected from Mexico, Florida (USA) and Costa Rica.

Curiously, the new species Carychium hardiei was discovered by accident by Dr. Jochum en route to the Atlanta Airport during a rest stop in Georgia (USA). The snail is named after the American naturalist and field biologist Frank Hardie. Another species, Carychium belizeense, was found in the Bladen Nature Reserve in Belize and is named after its country of origin. The third, Carychium zarzaae from Panama, is named after Eugenia Zarza, collector of material for this study, including this species.

In total, there are fourteen species of thorn snails known in North and Central America. Their distribution ranges from as far north as northern Ontario, Canada through North America (including Bermuda and Jamaica) and south through Central America to Costa Rica. Thorn snails also live as far north as northern Sweden and as far south as sub-equatorial Java. Worldwide, this genus spans the Nearctic, Palearctic and Indomalayan biogeographic realms.

Thorn snails live in tropical and temperate forests, meadows and riparian zones, where they comprise the decomposer community in leaf litter of ecologically stable environments.

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Original Source:

Jochum A, Weigand AM, Bochud E, Inäbnit T, Dörge DD, Ruthensteiner B, Favre A, Martels G, Kampschulte M (2017) Three new species of Carychium O.F. Müller, 1773 from the Southeastern USA, Belize and Panama are described using computer tomography (CT) (Eupulmonata, Ellobioidea, Carychiidae). ZooKeys 675: 97-127. https://doi.org/10.3897/zookeys.675.12453

Species new to science named after a ‘Dungeons & Dragons’ character

Focused on terrestrial gastropods, more commonly known as land snails, a joint team of biologists from the Natural History Museum of Stuttgart, Germany and the Zoology Museum of São Paulo, Brazil, have been researching Brazilian caves.

In their latest paper, published in the journal Zoosystematics and Evolution, the scientists describe the fauna from several caves in central Brazil, including a new tiny species named after a character from the popular fantasy tabletop role-playing game Dungeons & Dragons.

The team of Dr. Rodrigo Salvador, Daniel Cavallari and Dr. Luiz Simone encountered a rich assembly of species, several of which measured only a few millimetres.

Beyond filling important knowledge gaps, they went even further, discovering a land snail new to science. While it is not uncommon for studies dealing with the invertebrate fauna to end up describing new species, this minute mollusc (nearly 2 mm in length) attracted extra attention. The team named it Gastrocopta sharae, after Shar, the goddess of darkness, caverns and secrets in Dungeons & Dragons.

“It’s a fitting name for a tiny snail that lives hidden in the dark recesses of a cavern,” explain the authors. “If your knowledge of mythological beings seems to have failed you, do not fret. Usually biologists tend to honour Greek and Roman deities when naming species, but the goddess Shar has a more colourful background. She is from Dungeons & Dragons, the most famous role-playing game in the world, currently in its 5th edition and a staple of geek culture.”

This is not the first time that Dungeons & Dragons has been immortalised in a species’ scientific name. In 2014, the very same team described another tiny snail, this time, one with a taste for deep waters, specifically those of the Atlantic Ocean. The scientists named it Halystina umberlee, after another Dungeons & Dragons goddess, Umberlee, who commands the harshness and perils of the sea.

Tropical snails are still poorly understood, and they are one of the most threatened animal groups – both from human activities and environmental changes. Moreover, since cave-dwelling invertebrates, in general, receive scarce attention from researchers, it should come as no surprise that cave-dwelling snails are even less known.

“Getting to know the fauna inhabiting each cavern is a demanding task, but a much-needed one,” note the researchers. “Caverns are known to have very fragile ecosystems and several lack proper protection, so works like ours are an important step for conservation efforts.”

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Original source:

Salvador RB, Cavallari DC, Simone LRL (2017) Taxonomical study on a sample of land and freshwater snails from caves in central Brazil, with description of a new species. Zoosystematics and Evolution 93(1): 135-141. https://doi.org/10.3897/zse.93.10995

New species of pea-size crab parasitizing a date mussel has a name of a Roman god

Tiny crabs, the size of a pea, dwell inside the mantles of various bivalves, living off the food filtered by their hosts. A new species of these curious crustaceans has recently been reported from the Solomon Islands, where an individual was found to parasitise a large date mussel.

Because of the new pea crab’s characteristic large additional plate, covering its upper carapace, giving it the illusion of having two faces, it has been named after Janus, the Roman two-faced god. Discoverers Dr Peter Ng, National University of Singapore, and Dr Christopher Meyer, U.S. National Museum of Natural History, Smithsonian Institution, have their findings published in the open access journal ZooKeys.

Being only the second species in the genus (the first was from Malaysia), the new pea crab Serenotheres janus can be distinguished by its broader carapace and other features. It is cream-yellow in colour.

Both representatives of the genus are unique in having an additional large plate covering the upper side of the carapace. However, its purpose is still unknown. The two pea crabs are also the only known parasites of the rock-boring bivalves of the mytilid subfamily Lithophaginae.

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Original source:

Ng PKL, Meyer C (2016) A new species of pea crab of the genus Serenotheres Ahyong & Ng, 2005 (Crustacea, Brachyura, Pinnotheridae) from the date mussel Leiosolenus Carpenter, 1857 (Mollusca, Bivalvia, Mytilidae, Lithophaginae) from the Solomon Islands. ZooKeys 623: 31-41. doi: 10.3897/zookeys.623.10272

Brushing off the dust: New snail species found lying in a museum since the 19th century

Having been collected back in the 19th century during an expedition in South America, a rather small snail species has been sitting around on the shelves of Madrid’s National Museum of Natural Sciences ever since. Covered in more than a century-old dust, it was described as new only recently when an obscure specimen placed in the long tail of a historical collection drew the attention of Drs. Breure and Araujo. Their research is now published in the open-access journal ZooKeys.

The small snail species, called P. cecepeus, had been staying ‘undercover’ for more than a century and a half among the numerous specimens, that formed a total of 20 new species when they were gathered during the historical ‘Comisión Científica del Pacífico’ expedition in South America. With the average undescribed museum invertebrate’s ‘shelf life’ being 20.7 years, it comes as no surprise that the herein described mollusc attracted the attention of the scientists.

Other than its moderately small size, the new species has been characterised with an irregular shape and narrow reddish-brown streaks running vertically across the shell. The surface is rather glossy and coloured in light chestnut-brown.

Although it has been accepted that the snail was found in Ecuador, the authors argue that the locality is “unfortunately very imprecise,” given the data supplied by the collectors. Therefore, the researchers suggest that additional field work should be done in the area so that the “true home” of their discovery is finally recorded.

“Although description of new species that have remained unnoticed for more than a century remains a rare event, it highlights the need for revisions of museum collections and especially the historical parts of these,” conclude the researchers.

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Original source:

Breure ASH, Araujo R (2015) A snail in the long tail: a new Plekocheilus species collected by the ‘Comisión Científica del Pacífico’ (Mollusca, Gastropoda, Amphibulimidae). ZooKeys 516: 85-93. doi: 10.3897/zookeys.516.10228