Caridean shrimps of the genus Synalpheus are abundant and widely distributed in tropical and subtropical regions, but knowledge of their reproductive biology remains scarce. We report reproductive traits of Synalpheus apioceros from Bocas del Toro, Panama, based on collections in August 2011. The 46 ovigerous females that were analyzed ranged in size from 3.8 to 7.4 mm in carapace length. Fecundity varied between 8 and 310 embryos and increased with female size. Females invested 18.6 ± 10.3% of their body weight in Embryo production. Embryo volume increased considerably (77.2%) during embryogenesis, likely representing water uptake near the end of incubation period. Compared to Synalpheus species with abbreviated or direct development, Synalpheus apioceros produced substantially smaller embryos; however, Synalpheus apioceros seems to have a prolonged larval phase with at least five zoeal stages, which may explain the combination of relatively small and numerous embryos. We did not find nonviable, minute, chalky embryos, previously reported for Synalpheus apioceros specimens obtained from the northwestern Gulf of Mexico, which supports the hypothesis that the production of this type of embryos may be a physiological response of this warm-water species to the temperature decrease near to its latitudinal range limit.