Description of Harperalpheus pequegnatae, new genus, new species from the Gulf of Mexico and Atlantic coast of the southeastern USA (Crustacea, Decapoda, Alpheidae)

A new genus, Harperalpheus, gen. nov., is established for H. pequegnatae, sp. nov., on the basis of specimens collected from sandy subtidal sediments off Galveston, Texas, and Sapelo Island, Georgia, USA. The holotype female, the largest and most intact specimen of the type series, is ovigerous and bears an appendix masculina on the second pleopod. The new genus is characterised by conspicuous, robust, equal sized chelipeds, which distinguish it from other known sympatric alpheid genera that lack an articulated posteroventral plate on the sixth abdominal pleuron. Additional distinguishing features of Horperalpheus, gen. nov., are the sharply produced pterygostomial angle of the carapace, orbital hoods concealing the eyes in dorsal view and lacking extracorneal teeth, the distinct rostrum having a posteriorly extended ventrorostral. keel, and the third maxilliped bearing a uniquely bilobed lateral plate on the coxa and lacking an arthrobranch. While this new species is not readily allied to any presently known alpheid genus, it appears to have some affinities with Coutieralpheus Anker and Felder, 2005, Salmoneus Holthuis, 1955, and Parobetaeus Coutiere, 1896.