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Brazil contains about 5% (~120 spp.) of the total known species of freshwater decapods. Information on the occurrence of freshwater decapod species in the state of Minas Gerais is dispersed and much of this remains unpublished. We hereby propose to present the first inventory of freshwater decapods from the state, based on data compiled from publications and scientific collections and obtained from fieldwork in the state. Eleven species of freshwater decapods were recorded in Minas Gerais, including three species of crabs (Trichodactylidae), seven of shrimps (Palaemonidae) and one species of freshwater squat lobster (Aeglidae), classified into three infraorders, three families, and four genera. The genus Macrobrachium C.S. Bate, 1868 comprised most of the decapod records. The reduced number of species in relation to coastal states is related, at least in part, to the absence of amphidromic species. Environmental degradation and the construction of dams in several watersheds may be possible causes of this absence. The records obtained from surveys carried out in national parks situated in Minas Gerais and its surroundings indicate the importance of these areas for the conservation of decapod fauna in the state.

The early larval stages of the shrimps Lysmata ankeri and L. bahia were described, illustrated, and compared among other Lysmata species, providing important information on post-embryonic development and insights into its evolutionary history. Ovigerous specimens of L. ankeri and L. bahia were sampled from southeastern and northeastern Brazilian coast, respectively. For L. ankeri and L. bahia, five and three larval stages were obtained, respectively. Unique features were observed for L. ankeri and L. bahia larvae, and some characteristics may differ only for L. ankeri and L. bahia, which were not observed in the other species analyzed, such as: presence of a pair of simple setae on the third pleonal somite in zoea I and number of setae on the uropod exopod greater than 11. Moreover, several other features are similar between species from the diferent clades of the Lysmata-Exhippolysmata complex, making it possible to identify the early stages of Lysmata larvae. However, future studies will be essential to confirm or not the existence of some phylogenetic patterns and their relevance and other larval characters for better understanding the evolutionary history of this group.

The complete larval development of Amphithrax hemphilli was described, illustrated, and compared with that of the previously described larvae of the genus Mithrax sensu lato. Specimens of A. hemphilli were sampled from the northeastern Brazilian coast. The larval development of A. hemphilli consisted of two zoeal stages and one megalopa. Amphithrax hemphilli shows morphological features in all stages of larval development that differ from those observed in other species of Amphithrax, Mithrax, and Maguimithrax. In the first larval stage, A. hemphilli was the only species with two aesthetascs on the antennule and the coxal endite of the maxillule with five setae. In the second larval stage, A. hemphilli was distinguished from the other species of the genus Mithrax sensu lato by the presence of five setae on the basial endite of the maxilla and 26 setae in the scaphognathite of the maxilla. Finally, the megalopa stage of A. hemphilli is characterized by the number of aesthetascs on the three-segmented exopod of the antennule, the setation of both the endopod of the third maxilliped, and pleonites 1-6. Based on the results obtained in the present study, we verified that the more advanced the larval stage, the more distinct characteristics are observed among species of the genus Mithrax sensu lato, facilitating the identification of species through later larval stages.

We evaluated the taxonomic composition of decapod crustaceans from the continental shelf of the Brazilian state of Sergipe. The specimens were collected during two field campaigns that covered the entire shelf length, at depths of 5-30 m. In the first campaign ("Petro-UFS"), four samplings took place between 1999-2000. In the second one ("Penaeid"), monthly samplings were carried out in 2013-2014, and covered an area at and between two important estuaries. Overall, we examined 74,387 decapod crustacean specimens. These specimens belonged to 27 families and 78 species, of which 26 species are newly recorded from Sergipe. Considering these results and previous records, Sergipe now has 121 species of marine decapod crustaceans, which represents only ~20% of the species recorded in the northern and northeastern Brazil. This gap indicates that the crustacean richness of Sergipe is probably underestimated and likely to increase with further samplings, especially on artificial rocky shores, rhodoliths and algae banks, small coralline formations, and other unexplored estuarine habitats.