It was filed as B. giganteus “because it fitted into the reported distribution range of this species, and it remained in the collection for decades,” the authors write.<\/p>\n\n\n\n
“In shape, these marine giant isopods resemble woodlice, the much smaller land isopods found in caves and damp basements,” the university’s announcement explains. Some species grow to about 20 inches (50 centimeters) and weigh several kilograms, and they live as deep as 8,200 feet (2,500 meters), scavenging “the carcasses of fish, squid, whales, and other marine animals,” the paper notes. One even turned up when Chinese researchers lowered a dead cow to the seafloor<\/a>.<\/p>\n\n\n\n “Bor\u00edken is the indigenous Ta\u00edno name for Puerto Rico, combined with the name of the city of T\u00fcbingen, Germany, where the specimen was rediscovered after being stored in the collection for the past decades,” the authors explain of the new name.<\/p>\n\n\n\n The holotype, the single specimen that now defines the species, is a female cataloged as GPIT-PV-94341. Its yellow-beige color comes from drying, and it measures 129 millimeters (5.1 inches) at its widest point.<\/p>\n\n\n\n K\u00e4stle and Werneburg photographed the animal and scanned it with an X-ray micro-CT scanner, which builds a 3D image from thousands of thin cross sections, 4,711 in this case. “The \u00b5CT permitted the detailed observation of the mouthparts, which are often neglected in species descriptions of Bathynomus although this anatomical area is useful for the taxonomy of Cirolanidae,” they write, referring to the family that giant isopods belong to.<\/p>\n\n\n\n The clearest mark of the new species sits on the seventh pair of walking legs, where a row of 15 comb-like curved bristles runs along one segment. The authors say it is unlike anything reported in the genus, “assuming this character was not overlooked by previous authors,” and suggest it was “possibly utilized for grooming the pleopods,” the paddle-like limbs under the tail end.<\/p>\n\n\n\n “The new species is very closely related to another giant species found off the Yucat\u00e1n Peninsula in Mexico,” K\u00e4stle said in a university statement.<\/p>\n\n\n\n That cousin, Bathynomus yucatanensis, was described in 2022 by a team including Ming-Chih Huang of the National University of Tainan in Taiwan. Their 10-inch (26-centimeter) specimen, trapped in 2017 at about 2,000 to 2,600 feet (600 to 800 meters) in the Gulf of Mexico, was at first taken for a variant of B. giganteus too.<\/p>\n\n\n\n “Bathynomus giganteus was discovered over a century ago, and more than 1,000 specimens have been studied with no suggestion until now of a second species with the same number of pleotelsonic spines,” that team wrote, according to a 2022 Taylor & Francis release<\/a>. “Superficial examination, using only pleotelson spines, could easily result in specimens of B. yucatanensis being misidentified as B. giganteus.”<\/p>\n\n\n\n “It is increasingly evident that species of Bathynomus may be exceedingly similar in overall appearance, and also that there is a long history of misidentification of species in the genus,” they added. Werneburg and K\u00e4stle reach the same point four years later, writing that misidentifications “often default to B. giganteus” and have “masked the actual extent of diversity within the genus.”<\/p>\n\n\n\n To place the new species, the pair coded 22 descriptive traits and 21 counts and measurements for 23 living and four fossil Bathynomus species, then ran phylogenetic analyses, which sort species into a tree by shared features. The trees point to the Caribbean region as the cradle of the genus and reconstruct up to 10 migration waves across the world’s oceans.<\/p>\n\n\n\n According to the university, the genus likely arose in what is now the Gulf of Mexico during the Miocene, more than 15 million years ago. “At that time, the Isthmus of Panama was open, leaving a strait between North and South America, and the marine animals were able to spread westward, initially as far as Japan,” Werneburg said.<\/p>\n\n\n\n “This gave rise to the so-called ‘giant’ isopods that are up to 15 centimeters long, and the ‘supergiants’ with a body length of more than 15 centimeters,” K\u00e4stle added. Some lineages later reached Australia, East Africa and Europe, where they eventually disappeared, and two or three appear to have found their way back to the Americas.<\/p>\n\n\n\n In a later branch of the tree, the authors found a single jump in body size of more than 60 millimeters (2.4 inches), about 30 percent, and coined a term for the species on the far side of it. They call animals of at least 255 millimeters (10 inches) “colossogiants,” and they tie the jump to a cooling of the Earth late in the Pliocene epoch.<\/p>\n\n\n\n “Our T\u00fcbingen specimen from Puerto Rico, measuring 32.2 centimeters in length, falls into the category of ‘colossogiants,'” K\u00e4stle said. Werneburg said those animals were “physiologically perfectly adapted to the new climatic conditions.”<\/p>\n\n\n\n The reported living depths “do not correlate with body size in Bathynomus in our phylogenies,” the authors write, “which shows that the conditions in very deep seas do not necessarily foster the evolution of large body size.”<\/p>\n\n\n\n “The Indian and Pacific regions currently account for more than 15 species, and the Americas for seven species,” the authors write, a gap they put down to “more intensive sampling efforts and recent taxonomic attention” in the Indo-Pacific. “This underscores the likelihood that many undescribed or misidentified species exist within museum collections worldwide,” they write.<\/p>\n\n\n\n Museums have surprised scientists like this before, as when a pangolin skin collected in 1836 turned out to belong to a species hiding in plain sight<\/a>, and a bone from Antarctica labeled as a marine reptile sat in a museum drawer for 40 years<\/a> before experts recognized a titanosaur.<\/p>\n\n\n\n Everything here comes from a single dried female, studied through its anatomy rather than its DNA. The authors describe their analyses as preliminary and warn that “the low bootstrap values,” a score of how strongly the data back each branch, “always require caution with any interpretation of the evolutionary history of a single species in our phylogenies.”<\/p>\n\n\n\n “After finalizing our paper, three new species were published and are not yet included in our analysis,” the authors note, and the depth records “need to be handled with care, because they are often just single recordings,” they write. “When using morphological data, first of all, however, it will be important in the future to consider the variation of characters within and among populations to distinguish species from ontogenetic, sexual, or regional variants,” they add.<\/p>\n\n\n\n “Our study presents only the first, preliminary step of a comprehensive Bathynomus phylogeny research agenda, awaiting a series of revisions using comparative phylogenetic methodology,” they conclude.<\/p>\n\n\n\nA name from T\u00fcbingen and Bor\u00edken<\/h2>\n\n\n\n
Fifteen curved bristles on the last leg<\/h2>\n\n\n\n
![\"Underside](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/10\/en-112-medio1-giant-isopod-underside-legs.jpg\")
A close cousin had the same problem<\/h2>\n\n\n\n
A family tree for every giant isopod<\/h2>\n\n\n\n
A new size class called colossogiants<\/h2>\n\n\n\n
![\"Three](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/10\/giant-isopod-three-views-fig2.jpg\")
More species are probably sitting on shelves<\/h2>\n\n\n\n
What one dried specimen cannot settle<\/h2>\n\n\n\n