A new hermit crab: Pylopaguropsis mollymullerae

Pylopaguropsis mollymullerae, Image from publication

Hermit crabs belong to the crustacean superfamily Paguroidea. There are about 1,100 known species of them. The abdomen of those crabs is soft, unlike the hard, calcified ones seen in other crabs. In order to protect it from predators these crabs salvage empty seashells and carry them around. When in danger they can retract their whole body in it.

A new species of hermit crab was found off Bonaire, an island off Venezuela’s coast in the southern Caribbean. The new species was named to acknowledge the efforts of the collector, photographer and environmentalist, Ellen Muller, who when informed of the intended honor, preferred that the name of her granddaughter, Molly Muller, be used, in the hopes to inspire her to continue the tradition of protecting the fragile marine diversity in Bonaire.

For the experts: A new secretive, yet brightly colored hermit crab species of the family Paguridae, Pylopaguropsis mollymullerae sp. n., is fully described based on specimens from the reefs of Bonaire, Lesser Antilles, southern Caribbean Sea. Populations of this new species were discovered and photographed in the Bonaire National Marine Park under a large coral ledge, at a depth of 13.7 m, living in crevices known by scuba divers to serve as den to a pair of “flaming reef lobsters” Enoplometopus antillensis, or a “broad banded moray” Channomuraena vittata. This new species is only the second species of Pylopaguropsis Alcock, 1905 known from the western Atlantic, the 20th named worldwide, and belongs in the teevana group of species of the genus. It is remarkably similar, and herein considered geminate, to the tropical eastern Pacific congener, P. teevana (Boone, 1932), the two being characterized and uniquely different from all other species of the genus, by the striking and deeply excavated, scoop-like ventral surface of the chela of the right cheliped. Minor differences separate this new species from P. teevana in the relative length of the antennal acicles (exceeding the corneas versus not exceeding the corneas in P. teevana); dorsal armature of the right chela (smooth or with scattered minute tubercles versus with numerous small tubercles in P. teevana); surface shape of the lateral face of the dactyl of right pereopod 3 (evenly convex versus flattened in P. teevana); and coloration (red bright red stripes versus brown stripes in P. teevana). The highly visible color pattern of bright red stripes on white background typical of decapods known to have cleaning symbioses with fish, dense setation on the flagella of the antennae, and preference for a crevicular habitat, combined with brief in situ nocturnal observations, suggests the possibility that P. mollymullerae sp. n. engages in “cleaner” activities or functions as a “den commensal” with moray eels. The morphology and possible meaning of the observed behavior is discussed. A tabular summary of the distribution, habitat, and published information on all species of Pylopaguropsis is presented. Supplemental photographs and a video of live P. mollymullerae sp. n. are included.