German paleontologist Dolf Seilacher had not yet won his Crafoord (the prestigious honor bestowed by the same Swedish academy that awards the Nobel Prize) when he was collecting specimens in Puerto Rico back in the 1980s. The research station had removed a gigantic Bathynomus isopod, a huge insect-like crustacean about 32.2 centimeters (12.7 inches) long, from a trap that had been lurking at 500 meters (1,640 feet) deep along the ocean floor. Sadly, Seilacher passed away in 2014, long before he or anyone else realized that this specimen was actually representative of a previously unknown species. Now, more than three decades after it was extracted from the Caribbean, Tübingen paleontology student Benedikt Kästle and the curator of the university’s Paleontological Collection, Ingmar Werneburg, have finally given this creature a name of its own. This giant, mealybug-like isopod, long mislabeled as Bathynomus giganteus, has now been formally identified with the new species name, Bathynomus tuebingoborikensis. “The new species is very closely related to another giant species found off the Yucatan Peninsula in Mexico,” Kästle said in a statement, noting that this heavy isopod technically “falls into the ‘colosogiant’ category.” Dorsal (A) and ventral (B) views of the isopod, whose mouth region was critical for its identification as a new species. The scale bar is equal to 1.97 inches (5 centimeters). Credit: Kästle, Werneburg Living Large To get even more technical, giant underwater isopods actually come from the same order of crustaceans as mealybugs, like the tiny brick mealybug (Porcellio spinicornis) seen lurking among masonry and stonework throughout Europe and North America. But unlike those insect-like terrestrial crustaceans, which only grow between 10 and 15 millimeters (0.4 and 0.6 inches) long, species in the gigantic genus Bathynomus can reach up to 50 centimeters (20 inches), making them some of the largest invertebrates on Earth. These Starship Troopers-like critters can also get heavy: up to 5.7 pounds (2.6 kilograms) in some cases, encased within sturdy exoskeletons suitable for depths up to 8,200 feet (2,500 meters) below sea level. According to Werneburg, the entire genus Bathynomus, which today can be found in oceans around the world, probably first took shape in the Gulf of Mexico during the Miocene epoch, more than 15 million years ago, not far from where B. tuebingoborikensis was found. “At that time, the Isthmus of Panama was open, leaving a strait between North and South America, and marine animals were able to spread westward, initially to Japan,” Werneburg explained in a statement. Prehistoric isopods took about 10 million more years, until the boundary between the Miocene and the Pliocene, to evolve into species close to the size of the largest representatives of the current crustacean. As the Earth cooled, the so-called “giant” isopod species of the Miocene, which only reached 5.9 inches (15 cm) in length, eventually gave rise to much larger cousins in the Indian and Pacific Oceans. “These true colossi grew to more than 25.2 centimeters in length and were physiologically perfectly adapted to the new climatic conditions,” says Werneburg. The great insect hunters, Kästle and Werneburg, turned to 3D imaging using micro-computed tomography to take the granular sections of the Tübingen specimen necessary to properly distinguish it from the other “colosogians” with which it had been confused. The late Seilacher, in his time, was somewhat known for achieving his landmark achievements without even the use of a computer, so it is perhaps not surprising that the subtle but numerous features that distinguish B. tuebingoborikensis failed to capture his attention. Microcomputed tomography “allowed detailed observation of the mouthparts, which are often overlooked in descriptions of Bathynomus species, although this anatomical area is useful for the taxonomy of [aquatic isopods or] Cirolanidae,” the pair wrote in their new study, published Thursday in Scientific Reports. In a nod to the species’ long journey, the researchers chose its name as an acronym for the indigenous Taíno name for Puerto Rico, Boríken, and the city of Tübingen, Germany, where Seilacher helped preserve the find for its unexpected rediscovery.
