ABSTRACT Branchinectamexicana, new species, a fairy shrimp from central Mexico, is described and figured. Its principal diagnostic characteristic is a squamate appendix on the median side of the basal antennal article. The proximal peglike part of this appendix extends into a posterodorsally directed tip, while its distal part shows 2-5 incisions. Differential features between the new species and the related species B. packardi Pearse are discussed on the basis of a SEM analysis. Branchinecta mexicana, new species, represents the southernmost record of a branchinectid in North America. No other phyllopod species were found at the time of its collection.