Background:

Recent morphological and phylogenetic studies of Laurencia in the Atlantic Ocean have modified our cu rrent knowledge of the group. Approximately 23% of the worldwide generic diversity has been recorded in this region.

Goals:

Update the checklist of the Laurencia species in the Atlantic and describe the distribution patterns within the ge nus.

Methods:

We obtained records of Laurencia species in the Atlantic from a review of the literature and distributional data were used to define areas of endemism through a PAE (Parsimony of Areas of Endemism) analysis.

Results:

We propose an updated checklist of the 30 currently recognized species of Laurencia in the Atlantic Ocean; this checklist also includes taxonomic synonyms, nomenclatural remarks, and a detailed distribution for each species. The distributional range for the genus in the Atlantic extends from Bermuda and Northern Europe in the North Atlantic to Brazil and South Africa in the South Atlantic. We were able to define four areas of endemism: Brazil with four endemic species, the Gulf of Guinea with four endemic species, the northeastern Atlantic with three endemic species, and South Africa with four endemic species; also documented was one secondary area (Macaronesian Islands) with the endemic species L. viridis. Moreover, 17 of the 30 species of the Atlantic are also distributed in the Indo-Pacific, of which five are amphi-Atlantic species.

Conclusions:

The patterns found are related to geological events that occurred in the past, a fact that allows us to formulate a vicariance hypothesis about these species biogeographic history. Therefore, future work that will document new species and the clarification of taxonomic problems will allow researchers to continue enriching this hypothesis.