The genus Surinamysis (Mysida, Mysidae, Diamysini) from Amazonia and the coast of Brazil, with descriptions of two new species

Abstract

The mysid Surinamysis rionegrensis sp. nov. is described from Rio Negro, a large freshwater tributary of the Amazon. A supplemented description is given for the freshwater species S. robertsonae Bamber & Henderson, 1990, and its known distribution within the Amazon system is amended. A further representative of this genus, S. aestuaria sp. nov., is described from brackish waters within the estuary system of Rio Quatipuru on the NE coast of Brazil. These three species share large statoliths mineralized with vaterite, a metastable polymorph of crystalline calcium carbonate. Among the three flagella of the male antennula, the median, ventral one is identified as an accessory flagellum, as opposed to the Old World genera Mesopodopsis and Limnomysis, where the inner flagellum or lobe is accessory. The distinctive characters of Surinamysis and its five species are presented. The diagnosis of this genus is modified and a key to its species is given.