Dulichiella celestun, a new species of amphipod (Crustacea: Amphipoda: Melitidae) from the Gulf of Mexico, with a key and zoogeographic remarks for the genus in the western Atlantic.

The discovery of a new melitid amphipod in the Celestun Biosphere Reserve (northern Yucatan peninsula, SE Gulf of Mexico) is reported. Dulichiella celestun sp. nov. differs from its congeners by an unique set of characteristics: truncated lateral cephalic lobe, mandibular palp article 1 having inner margin produced distally, carpus longer than the propodus of gnathopod 1, gnathopod 2 propodus distolateral crown with four spines, pereopods 3-7 dactylar unguis anterior margin with two accessory spines, and urosomite 3 bearing four dorsal spines. A key to species and zoogeographical affinities among members of the genus in the western Atlantic are also provided.