It was discovered while working on the 1001 Seaforest Species project, which focuses on raising awareness about the rich kelp bed ecosystems of South Africa.
An unusual galeommatid clam, Melliteryx mactroides, living in tidepools near Cape Town, South Africa. Video by Jannes Landschoff
Published in the scientific journal ZooKeys, the study focuses on four species of galeommatoidean bivalves collected from the Western Cape region of South Africa. Among these is one new species, Brachiomya ducentiunus. This small clam, which is only 2 mm (less than 1/8th inch) in length, spends its life crawling between the spines of sea urchins.
The newly discovered species, Brachiomya ducentiunus, crawing on a sea urchin spine. Photo by Craig Foster
The new species has so far only been found in one locality in False Bay, South Africa, where it was found attached to the burrowing sea urchin Spatagobrissus mirabilis in coarse gravel at a depth of about 3 m. It has not been observed free-living, without the host urchin.
Brachiomya ducentiunus was discovered while preparing and working on the 1001 Seaforest Species project, a research and storytelling program aimed at increasing awareness of regional kelp bed ecosystems colloquially referred to as ‘the Great African Seaforest’.
Dozens of the new species crawling on the surface of a sea urchin. Photo by Charles Griffiths
“This study marks a significant advancement in our understanding of the biodiversity and ecological interactions of galeommatoidean bivalves,” says lead author Paul Valentich-Scott. “By uncovering the hidden lives of these small but ecologically important organisms, we hope to contribute to the broader knowledge of marine biodiversity and the conservation of these unique habitats.”
Co-author Charles L. Griffiths, emeritus professor at the University of Cape Town, says, “A large proportion of smaller marine invertebrates remain undescribed in western South Africa and almost any project that samples specialized habitats turns up many new records and species.”
The new clam species feeding between the spines of a sea urchin. Video by Craig Foster
In a similar vein, co-author Jannes Landschoff, marine biologist at the Sea Change Trust, says “Creating foundational biodiversity knowledge is a most important step to the humbling realization of how fascinating and uniquely diverse a place is. I see this every day through our work in the rich coastal waters of Cape Town, where an extensive underwater kelp forest, the ‘Great African Seaforest,’ grows.”
Research article:
Valentich-Scott P, Griffiths C, Landschoff J, Li R, Li J (2024) Bivalves of superfamily Galeommatoidea (Mollusca, Bivalvia) from western South Africa, with observations on commensal relationships and habitats. ZooKeys 1207: 301-323. https://doi.org/10.3897/zookeys.1207.124517
Discovering a new species is always exciting, but so is finding one alive that everyone assumed had been lost to the passage of time. A small clam, previously known only from fossils, has recently been found living at Naples Point, just up the coast from UC Santa Barbara. The discovery appears in the journal ZooKeys.
“It’s not all that common to find alive a species first known from the fossil record, especially in a region as well-studied as Southern California,” said co-author Jeff Goddard, a research associate at UC Santa Barbara’s Marine Science Institute. “Ours doesn’t go back anywhere near as far as the famous Coelacanth or the deep-water mollusk Neopilina galatheae — representing an entire class of animals thought to have disappeared 400 million years ago — but it does go back to the time of all those wondrous animals captured by the La Brea Tar Pits.”
Jeff Goddard with students. Photo Credit: Courtesy Image
On an afternoon low tide in November 2018, Goddard was turning over rocks searching for nudibranch sea slugs at Naples Point, when a pair of small, translucent bivalves caught his eye. “Their shells were only 10 millimeters long,” he said. “But when they extended and started waving about a bright white-striped foot longer than their shell, I realized I had never seen this species before.” This surprised Goddard, who has spent decades in California’s intertidal habitats, including many years specifically at Naples Point. He immediately stopped what he was doing to take close-up photos of the intriguing animals.
“I was surprised and intrigued. This was something I’d never seen before.”
Paul Valentich-Scott
With quality images in hand, Goddard decided not to collect the animals, which appeared to be rare. After pinning down their taxonomic family, he sent the images to Paul Valentich-Scott, curator emeritus of malacology at the Santa Barbara Museum of Natural History. “I was surprised and intrigued,” Valentich-Scott recalled. “I know this family of bivalves (Galeommatidae) very well along the coast of the Americas. This was something I’d never seen before.”
He mentioned a few possibilities to Goddard, but said he’d need to see the animal in-person to make a proper assessment. So, Goddard returned to Naples Point to claim his clam. But after two hours combing just a few square meters, he still hadn’t caught sight of his prize. The species would continue to elude him many more times.
Nine trips later, in March 2019, and nearly ready to give up for good, Goddard turned over yet another rock and saw the needle in the haystack. A single specimen, next to a couple of small white nudibranchs and a large chiton. Valentich-Scott would get his specimen at last, and the pair could finally set to work on identification.
A dazzling play of colors highlights Southern California’s long lost clam. Photo Credit: Jeff Goddard
Valentich-Scott was even more surprised once he got his hands on the shell. He knew it belonged to a genus with one member in the Santa Barbara region, but this shell didn’t match any of them. It raised the exciting possibility that they had found a new species.
“This really started ‘the hunt’ for me,” Valentich-Scott said. “When I suspect something is a new species, I need to track back through all of the scientific literature from 1758 to the present. It can be a daunting task, but with experience it can go pretty quickly.”
The two researchers decided to check out an intriguing reference to a fossil species. They tracked down illustrations of the bivalve Borniacooki from the paper describing the species in 1937. It appeared to match the modern specimen. If confirmed, this would mean that Goddard had found not a new species, but a sort of living fossil.
Cymatioa cooki. Photo credit: VALENTICH-SCOTT ET AL.
It is worth noting that the scientist who described the species, George Willett, estimated he had excavated and examined perhaps 1 million fossil specimens from the same location, the Baldwin Hills in Los Angeles. That said, he never found B. cooki himself. Rather, he named it after Edna Cook, a Baldwin Hills collector who had found the only two specimens known.
Valentich-Scott requested Willett’s original specimen (now classified as Cymatioacooki) from the Natural History Museum of Los Angeles County. This object, called the “type specimen,” serves to define the species, so it’s the ultimate arbiter of the clam’s identification.
The type specimen that George Willett used to originally describe the species. Photo credit: VALENTICH-SCOTT ET AL.
Meanwhile, Goddard found another specimen at Naples Point — a single empty shell in the sand underneath a boulder. After carefully comparing the specimens from Naples Point with Willett’s fossil, Valentich-Scott concluded they were the same species. “It was pretty remarkable,” he recalled.
Small size and cryptic habitat notwithstanding, all of this begs the question of how the clam eluded detection for so long. “There is such a long history of shell-collecting and malacology in Southern California — including folks interested in the harder to find micro-mollusks — that it’s hard to believe no one found even the shells of our little cutie,” Goddard said.
He suspects the clams may have arrived here on currents as planktonic larvae, carried up from the south during marine heatwaves from 2014 through 2016. These enabled many marine species to extend their distributions northward, including several documented specifically at Naples Point. Depending on the animal’s growth rate and longevity, this could explain why no one had noticed C. cooki at the site prior to 2018, including Goddard, who has worked on nudibranchs at Naples Point since 2002.
“The Pacific coast of Baja California has broad intertidal boulder fields that stretch literally for miles,” Goddard said, “and I suspect that down there Cymatioa cooki is probably living in close association with animals burrowing beneath those boulders.”
Research article:
Valentich-Scott P, Goddard JHR (2022) A fossil species found living off southern California, with notes on the genus Cymatioa (Mollusca, Bivalvia, Galeommatoidea). ZooKeys 1128: 53-62. https://doi.org/10.3897/zookeys.1128.95139
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.
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.
***
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
***
Follow the Subterranean Biology journal on Twitter and Facebook.
Even though the short-neck clam is the major resource and export coming from Ashtamudi Lake in Kerala, India – the first fishery to be awarded with a a Marine Stewardship Council certification for sustainability in the country, a recent study found out that the mollusc had been subject to mistaken identity.
Further, this is not the first time when the species and genus name of this clam has been changed. At first, the species was identified as Paphia malabarica, which is also the name one could read in all hitherto published reports, including the Marine Stewardship Council’s register. Later on, as the name was proved to not be compliant with the current nomenclature, the Ashtamudi short-neck clam began to be referred to as Protapes gallus.
Marcia recens from Ashtamudi lake, India.
However, the latest in-depth taxonomic study points to the clam having been misidentified from the very beginning. According to the finding of the team of A. Arathi, R. Ravinesh and A. Biju Kumar of the Department of Aquatic Biology and Fisheries, University of Kerala, and Graham Oliver of National Museum Wales, United Kingdom, the Ashtamudi short-neck clam belongs to a totally different genus, while its rightful scientific name actually is Marcia recens. Their paper was published in the open access journal ZooKeys.
During their research, the scientists identified another edible species from Ashtamudi Lake that belongs to the Marcia genus: Marcia opima. While it could easily be mistaken for its commercially important relative thanks to a multitude of colour variations, it does not appear to contribute significantly to the export. Meanwhile, the actual species identified as Paphia malabarica (Protapes gallus) can be found in shallow coastal waters in the south of the country, but not in the studied brackishwater lake.
“No deleterious effects on the viability of the fishery have resulted from this error in identification, but from a legislative perspective applying the incorrect name to the exploited species could undermine its certification and protection,” comment the researchers.
“On the basis of this study, the species involved in the Marine Stewardship Council certification would be better considered at the generic level of Marcia or at the species level for Marcia recens, the most dominant species in the Ashtamudi Lake clam fishery zone.”
In conclusion, the authors of the study say that, “misidentification can undermine comparative biological studies and conservation, while more molecular studies are required to resolve the taxonomy of all clams involved in fishery.”
###
Original source:
Arathi AR, Oliver PG, Ravinesh R, Kumar AB (2018) The Ashtamudi Lake short-neck clam: re-assigned to the genus Marcia H. Adams & A. Adams, 1857 (Bivalvia, Veneridae). ZooKeys 799: 1-20. https://doi.org/10.3897/zookeys.799.25829
