Thrombasia J.L. Barnard, 1966: 72.― Ledoyer, 1986: 810.
Schisturella.― Barnard & Karaman, 1991: 526 (in part).
Type species. Thrombasia tracalero J.L. Barnard, 1966, original designation.
Included species. Thrombasia includes six species: T. evalina sp. nov.; T. grabenis J.L. Barnard, 1967; T. rotundata (K.H. Barnard, 1926); T. saros sp. nov.; T. tracalero J.L. Barnard, 1966; T. umina sp. nov.
Diagnostic description. Antenna 1 flagellum article 1 lacking robust seta on distal margin; accessory flagellum forming cap. Antenna 2 flagellum articles 3–5 slender in female, article 3 enlarged in male; articles 3–5 with brush setae on the anterior margin. Mandibular incisor curved; molar a reduced column with convex triturating surface or proximally setose and distally triturating; palp attached midway. Maxilla 1 ST-7 serrate along the distomedial medial margin; ST-D slender, apically cuspidate. Maxilliped outer plate apical robust setae present. Gnathopod 1 subchelate; coxa slightly to greatly shorter than coxa 2, tapering distally; carpus slightly longer than propodus; propodus palm acute, straight. Pereopod 4 coxa with well developed posteroventral lobe. Uropod 2 inner ramus constricted. Uropod 3 rami plumose setae absent in female, present occasionally in adult male. Telson moderately cleft.
Remarks. The genus Thrombasia was established by Barnard (1966) for T. tracalero, and was subsequently placed in the synonymy of Schisturella by Barnard & Karaman (1991). However, we consider Thrombasia to be distinct from Schisturella based on the gnathopod 1 coxa, which is tapering and slightly reduced, not vestigial as in Schisturella. There are four other genera in the Tryphosa group with a gnathopod 1 coxa that is not vestigial. Of these, Thrombasia may be separated from Gronella by the gnathopod 1 carpus, which is longer than the propodus, from Tryphosa and Bruunosa in the tapering gnathopod 1 coxa, and from Glorieusella in the subchelate gnathopod 1.
Distribution. Pacific Ocean, South Atlantic Ocean.