LAUSR

A new monotypic genus of eusirid amphipod, Pseudorhachotropis gen. nov., is described and illustrated from a male specimen collected from bathyal soft bottoms (2321 m depth) in the southern Gulf of Mexico. The new genus is morphologically close to the genus Rhachotropis, previously documented from bathyal and abyssal deep-water worldwide. The new eusirid differs from other genera in having antenna 1 with 5-articulate accessory flagellum, mandibular molar smooth conical protuberance with large robust setae, pereonal segments smooth, pleonal segments 1-3 posterodistal notched, urosomal segments 1-2 with large posterodorsal processes, coxa 1 quadrangular unproduced anteriorly, uropod 1 interramal robust seta, epimeron 3 with three teeth posteroventral corner, telson as long as wide, "V" inverted shape incised 0.3 x posterior margin, each lobe 1-2 robust setae, besides the most important character to distinguish such genus includes molar palp article 1 long, subequal in length to article 2. A comparative table showing primarily features of the 14 known genera of eusirid amphipods, is also given.