Abstract Studies on fecundity and embryo size have been frequently used to infer about the reproductive potential, embryogenesis, and the energy investment in embryo production in crustaceans. These parameters are relevant to the knowledge of life-history and diversity of reproductive strategies developed by this group. This study addressed the embryo production by the estuarine shrimp Salmoneus carvachoiAnker, 2007, a poorly known caridean shrimp. We investigated whether there was (1) a correlation between fecundity and carapace length, (2) an increase in embryo volume along the embryonic development, and (3) loss of embryos along development. In addition, we investigated whether the esternite length and height and width of the pleura of the second abdominal somite were good predictors of fecundity. A total of 53 embryo-carrying individuals were collected in December 2016 and February 2017 in a tidal mudflat from the estuary of the Paripe River, Ilha de Itamaracá, Pernambuco, Brazil. The carapace length ranged from 3.23 to 4.64 mm (3.78 ± 0.26 mm). Among those, 25 individuals had embryos in initial stage, 5 in intermediate stage and 15 in final stage. Fecundity ranged from 14 to 67 (33.65 ± 12.51 embryos) and was weakly correlated with carapace length. However, fecundity was strongly correlated with the width of the second sternite and width of the pleura of the second abdominal somite. Embryo volume increased markedly (93%) from the initial to the final stage of development. This increase might be due to water uptake to facilitate the membrane rupture at the onset of larvae hatching. There was significant loss of embryos only between the initial and intermediate stage. Future studies on the embryo production by other species of Salmoneus Holthuis, 1955 are necessary to understand and compare these aspects of reproductive biology.

ABSTRACT The occurrence of the alien alpheid shrimp Athanas dimorphus Ortmann, 1894 is reported for the first time for the state of Pernambuco, northeastern Brazil, based on two ovigerous females collected at Praia do Paraíso, near the Suape Harbor (08º21'29.9"S 34º57'00.9"W). The species, native from the Indo-West Pacific region, was previously reported from two other Brazilian states (Ceará and São Paulo), also occurring in localities with nearby harbors. The presence of ovigerous females suggests that the species was successfully introduced into the area. The main possible introduction vectors for A. dimorphus in Pernambuco and the dispersal potential of the species along the Brazilian coast are discussed.