Diagnosis: Pereonites 6 and 7 dorsomedially fused. Body length about 5.5 times width of pereonite 2. Fine setules dispersed over dorsum, female with anteroventral spine on operculum. A 1 5 segmented, peducular article 4 with long lateral projection. A 2 flagellar article 1 o longer than last peduncular one, swollen. Mandible with palp. Mxp epipod very long and slender, reaching distal margin of palp article 3. P 14 with stout sensory setae on ventral margins of carpus and propodus, dorsal margins with stout setae. P 57 with very long and slender setae ventrally; propodus with long natatory setae dorsally and tiny setules. Urp with short, slender exopod; approximately 1 / 4 length of endopod; exopod 1 / 3 width of endopod.
Type species: Saetoniscus meteori n. sp.
Etymology: Saetoniscus is taken from the Latin saeta, seta, referring to the long slightly plumose setae on P 57 propodi. The gender of the name is masculine.
Distribution: abyssal Angola Basin, south Atlantic Ocean, 5389 m.
Remarks: Genera that most closely resemble the new genus Saetoniscus are Regabellator Siebenaller & Hessler, 1981 and Exiliniscus Siebenaller & Hessler, 1981. Regabellator, however, can easily be distinguished from Saetoniscus by the ventral spines on pereonites 6 and 7 and the missing natatory setae on P 57. Saetoniscus has an anteroventrally directed spine on the operculum. Regabellator has natatory setae on P 35. Natatory setae are absent in Saetoniscus. Pereonites 6 and 7 are dorsally fused in Saetoniscus and are not dorsally fused in Exiliniscus. Exiliniscus has a rostral process, which is absent in Saetoniscus. A 2 peduncular article 5 is swollen in Saetoniscus. A 2 flagellar article 1 of Exiliniscus is long and slender. Mxp epipod of Exiliniscus is short and the uropodal exopod in this genus is minute.