Using integrative taxonomy to establish the status of Alpheus peasei (Armstrong, 1940) (Decapoda: Alpheidae) as a single species throughout its distribution.

The distribution of the western Atlantic snapping shrimp Alpheus peasei (Armstrong, 1940) has a large gap (approx. 12° of latitude) between Tobago and the northeast of Brazil (State of Ceará). Here we analyzed specimens of A. peasei from its entire distribution range and type-locality (Bermuda), to test the hypothesis that they belong to a single species. The morphological analysis included the usual taxonomic characters as well as additional ones (such as mouthparts). The molecular analysis was based on the mitochondrial genes Cytochrome Oxidase I and 16S rRNA. The results of both analyses were congruent and indicated that A. peasei is a single species throughout its known distribution. As such, they indicated a connectivity between Northwestern and Southwestern Atlantic populations of A. peasei. The gap in distribution may be explained by scarce samplings in the North Brazil Shelf province and/or by passive larval dispersal. Our results also extend the known distribution of A. peasei in the northwestern Atlantic (Barbados, Belize and Costa Rica), and add a new record from the Brazilian coast (Pernambuco).