Tryphosa Boeck, 1871: 117.― Stephensen, 1925: 101 (in part).
Orchomene.― Barnard & Karaman, 1991: 507 (in part).
Tryphosella.―J.L. Barnard, 1969: 365 (in part).
Type species. Anonyx nanus Krøyer, 1846a, by monotypy.
Included species. Tryphosa includes two species: T. crenata (Chevreux & Fage, 1925); T. nana (Krøyer, 1846a).
Diagnostic description. Antenna 1 flagellum article 1 lacking robust seta on distal margin; accessory flagellum forming cap. Antenna 2 flagellum article 5 slender (with dense brush setae on the anterior margin). Mandibular incisor slightly curved; molar a reduced column with convex triturating surface (button); palp attached midway. Maxilla 1 ST-7 serrate along most of curved medial margin; ST-D slender, serrate along the entire curved medial margin. Maxilliped outer plate apical setae present. Gnathopod 1 subchelate; coxa large, nearly as long as coxa 2, not tapering; carpus slightly shorter than propodus; propodus palm slightly acute, straight. Pereopod 4 coxa with well developed posteroventral lobe. Uropod 2 inner ramus constricted. Uropod 3 rami with plumose setae in male and female; inner ramus broad, lanceolate. Telson deeply cleft.
Remarks. See d’Udekem d’Acoz & Havermans (2012) for a comprehensive summary of the historical taxonomic and nomenclatural treatment of Tryphosa.
Tryphosa is easily separated from Orchomenella, with which it has long been associated, by the constricted inner ramus on uropod 2.
Distribution. Northeast Atlantic, Mediterranean Sea, Adriatic Sea.