AbstractCurrently, 14 of the 50 species ofLysmataare known to possess a long accessory branch with more than two articles. Historically,Lysmata intermediaandLysmata mooreiwere the only two ‘long-branch’ species inhabiting the southwestern Atlantic. Here we describe, based on morphological, molecular and colour pattern data, a new species ofLysmatapossessing a long accessory branch from Pernambuco, northeastern Brazil. Our maximum-likelihood analysis recoveredLysmata elisasp. n. as a sister species toLysmata jundalini. Both species are closely related toLysmata holthuisiandL. intermedia. The four aforementioned species comprise theL. intermediaspecies complex. The new species may be morphologically distinguished from the other closely related species by different sets of characters, which include details of the dorsolateral antennular flagellum, armature of ischium of the second pair of pereiopods, intraorbital process shape and relative proportions of pereiopods. Our results reinforce the importance of refining biodiversity data through the application of integrative taxonomic approaches to expand the knowledge of local and global biodiversity. The biodiversity ofLysmatadeserves special attention, as they are intensively exploited in the aquarium trade.