A crustacean considered to be a giant with 14 legs and measuring more than 20 centimeters in length, discovered at a depth of 760 meters in the Peninsula of Yucatan, in the Gulf of Mexico, is a new species of isopod. called Bathonymus yucatanensisit was found right in the place where the asteroid that decimated the dinosaurs fell.
The species is a new type of isopod, a crustacean whose measurements usually do not exceed 10 millimeters in length. The 20 species found in the genus bathynomus, however, are about 30 times larger. They are evidence of a natural phenomenon called “oceanic gigantism”.
The specimen, captured in 2017, was believed to be a variation of the bathonymus giganteus —one of the largest found on the peninsula in 1879. A second species of isopod, the bathonymus maxeyorumwas described in 2016.
But the animal discovered on the Peninsula of Yucatan, it turned out, did not belong to any of these species. Maintained by the Aquarium of Enoshima in Japan, the individual was subtly different from his kin.
“Compared to B. giganteusO B. yucatanensis has slimmer body proportions and is shorter in length total — and the pereopods (legs) or forelimbs are more slender,” the study’s lead author, Professor Ming-Chih Huangfrom the National University of taianin Taiwan.
The crustacean also has longer antennae. The two species, however, have the same number of spines at the end of the tail. To be sure of the difference between them, the scientists performed a molecular genetic analysis comparing the crustaceans.
“Due to the different sequences of the two genes (COI and 16S rRNA), together with differences in morphology, we identified the B. Yucatanensis like a new species,” said Huang.
The researchers constructed a family tree that showed the B. yucatanensis as the closest to B. giganteus. “This indicates that the two species likely had a common ancestor,” concluded the scientist.