Stebbingiella Marques-Junior & Senna, 2013 in the family Paragammaropsidae (Crustacea, Amphipoda, Senticaudata).

The genus Stebbingiella Marques-Junior & Senna, 2013 was recently established in the family Melphidippidae Stebbing, 1899. Stebbingiella does not fit this family concept for a number of reasons which include: antenna 1 accessory flagellum well developed; callynophore absent; maxilla 1 inner plate with apical robust setae; maxilla 2 inner plate without oblique setal row; coxae discontiguous; gnathopod 2 sexually dimorphic, enlarged in males; pleonites without dorsal carinae; epimera absent; uropodal rami linguiform or lanceolate; uropod 3 with short peduncle, rami longer than peduncle; telson dorsoventally thickened. Stebbingiella is very similar to Paragammaropsis Ren, 1991 in the family Paragammaropsidae Myers & Lowry, 2003. Both are large amphipods (25 to 37 mm in length) living in deep water on the outer continental shelf and/or upper slope. In the habitus illustration of Marques-Junior & Senna, 2013 (465, fig. 1) the line at the base of the eye indicates a true pedunculate eye, known only for some ingolfiellideans among the Amphipoda. It is more probable that the Stebbingiella eye is similar to the eye of Paragammaropsis in which the lateral cephalic lobe is extremely extended and the eye is completely enclosed in the lobe. In this case the head looks very similar between these genera. Other similarities between these genera are: the mouthparts, particularly the reduced number of setal-teeth on the outer plate of maxilla 1 and the peculiar maxilliped in which palp article 2 is unusually elongate; the subcylindrical bodies with discontiguous coxae; the slender pereopods with linear basis; the undeveloped epimera; the carinate urosome; and the third uropods with elongate peduncles and rami much longer than the peduncles. Stebbingiella and Paragammaropsis differ in three key characters: the merus of pereopods 3 and 4 are linear in Stebbingiella and expanded in Paragammaropsis; urosomite 1 has dorsal setae in Stebbingiella, absent in Paragammaropsis; and uropod 3 outer ramus is linguiform and 2-articulate in Stebbingiella, lanceolate and 1-articluate in Paragammaropsis. Ren (1991) did not have males in his original material of Paragammaropsis prenes. Males of Stebbingiella globulosa Marques-Junior & Senna, 2013, indicate that gnathopod 2 is sexually dimorphic in this family. Paragammaropsis is known from the Bransfield Strait at the northern tip of the Antarctic Peninsula in 180 to 278 m depth and Stebbingiella is known from 268 m depth off the Brazilian coasts. Paragammaropsidae is currently known from the eastern South Atlantic Ocean from Brazil to the northern tip of the Antarctic Peninsula in the Southern Ocean.