retrodorsalis, Idiacanthus Thompson [W. F.] 1916:462, Pl. 4 (fig. 2) [Proceedings of the United States National Museum v. 50 (no. 2133); ref. 4391] Off Lota, Chile, 38°08'S, 75°53'W, Albatross station 2791, depth 677 fathoms. Holotype (unique): USNM 76857. •Synonym of Idiacanthus niger Regan 1914 -- (Regan 1916:379 [ref. 40111]). •Valid as Idiacanthus retrodorsalis Thompson 1915 -- (Pequeño 1989:33 [ref. 14125]). •Synonym of Idiacanthus atlanticus Brauer 1906 -- (Krueger 1990:341 [ref. 14983], Gon 1990:129 [ref. 21680]). Current status: Synonym of Idiacanthus atlanticus Brauer 1906. Stomiidae: Idiacanthinae. Habitat: marine.