Diagnosis. (Modified after Larsen 2005) Female. Body elongate (11.5–13 times as long as wide). Pereonites longer than wide, with straight lateral edges. Pleon short (15–20 % of total body length). Antennule shorter than carapace, with four articles. Antenna with six articles. Mandibular molar tapering with terminal spines. Maxillule with eight to ten spiniform terminal setae. Maxillipedal endite with medial lobes, spiniform lateral corners and robust distal seta. Cheliped carpus prominent and often with large carpal shield. Chela robust. Fixed finger with two robust (as wide as a pereopod unguis) ventral setae. Pereopods without coxae. Pereopods 1–3 basis wider than on pereopods 4–6; merus and carpus with robust spiniform setae. Pereopods 4–6 dactylus and unguis not fused; dactylus with double-row of small spines. Pleopods short and broad, with plumose or simple setae. Uropods prominent, often as long as antennae: endopod with two articles; exopod with one or two articles; specialized setae with a wide and flat basis present on either exo- or endopod.
Male. Antennule thicker than in female, functional mouthparts present (see remarks on new species).
Type species: Stenotanais crassiseta Bird & Holdich, 1984.
Gender of generic name: Masculine.
Species currently assigned to this genus: Stenotanais arenasi n.sp.: Stenotanais crassiseta Bird & Holdich, 1984; Stenotanais hamicauda Bird & Holdich, 1984; Stenotanais macrodactylus Larsen, 2005.