A new species of Hyalella from Brazil (Crustacea: Amphipoda: Hyalellidae), with redescriptions of three other species in the genus

The description of the new species Hyalella pseudoazteca and redescriptions of H. gracilicornis (Faxon, 1876), H. longistila (Faxon, 1876) and H. warmingi Stebbing, 1899, are included in this work. The latter species are closely related by having sternal gills on segments 2-7, and are morphologically distinct from other hyalellid species known from the area. Hyalella pseudoazteca has a morphology similar to H. azteca (Saussure, 1858). However, H. pseudoazteca has dorsal flanges instead of carinae on peraeon 7 and pleon 1 and 2, two distal setae on the inner plate of maxilla 1, and one pappose seta on the inner margin of maxilla, 2 inner plate. For comparisons with H. azteca see Gonzalez and Watling (2002).