A new species of Euryrhynchus Miers, with a discussion of the systematic position of the Euryrhynchidae Holthuis (Crustacea, Decapoda)

A new species of the South American freshwater genus Euryrhynchus, E. tomasi sp. nov., is described on the basis of two specimens from French Guyana. The new species differs from all its congeners by the presence of two disto-lateral spines on the merus of the second pereiopod, combined with the absence of any carpal spines. The recent elevation of the euryrhynchids to family status is supported, whilst a discussion is presented of their systematic position and affinities, emphasising the remote systematic affinity with the Typhlocarididae, previously assumed to be closely related. An appraisal of the systematically important characters in the Euryrhynchidae highlights the need for a re-appraisal of the caridean superfamily Palaemonoidea.