Abstract
Forty three species of leptocheliids are known worldwide. In the American region only eight species have been described from the Western Atlantic, while for the Eastern Pacific none have been described, suggesting that the diversity of this family has been severely underestimated in this region. Here we describe the first species of Leptochelia from the Eastern Pacific, Leptochelia mexicana n. sp., which is characterized by the males having a spiniform seta on the second segment of uropodal endopod, a novel feature for the genus. In addition, the first annotated checklist and a taxonomic key with illustrations for Leptochelia species are included. The list includes the type locality, type depository, distribution, habitat and, in some cases, remarks.