The tribe Eustylini was named for the first time by Jean-Baptiste Henri Lacordaire in 1863,[2] although, when first named, the tribe (Groupe Eustylides, p. 205) only contained three genera: Aptolemus (currently in Naupactini), Brachystylus, and Eustylus.
In 1986 the Eustylini contained most of its current genera, mostly due to revised taxonomic placements made by Guillermo Kuschel.[3][1] The latest additions were made by Franz in 2012 by transferring former members of other tribes including Geonemini, Phyllobiini, and Tanymecini.[4]
A diagnosis for the tribe was offered by Girón 2020:[6]
Medium to large weevils (approx. 10–25 mm); scale coverage highly variable in presence, density and coloration; iridescent scales, erect setae or waxy secretions are frequently present; surface smooth and even or strongly sculptured and irregular; head (including rostrum) subrectangular, nearly as long or longer than wide; eyes small to mid-sized, slightly dorsally positioned; frons usually as wide as or narrower than interantennal distance, often bearing median fovea; rostrum nearly parallel-sided or broadened apically; dorsal surface of rostrum with variable elevations or depressions, including longitudinal carinae or oblique fossae; antennal scrobe generally fully visible in dorsal view; nasal plate usually well developed, either depressed, flat or elevated regarding surface of rostrum; anterior margin of prothorax in lateral view straight, seldom slightly sinuate, never forming conspicuous postocular lobe; postocular setae may be present, if so, forming a fringe instead of a tuft; elytral shoulders usually well-developed, absent in Brachyomus, reduced in some Compsus and Exorides; tubercles and apical projections may be present on elytra; femora usually not toothed (except in some Eustylus).
— J.C. Girón, Status of knowledge of the broad-nosed weevils of Colombia (Coleoptera, Curculionidae, Entiminae).
^ abcdWibmer, G. J.; O’Brien, C. W. (1986). "Annotated checklist of the weevils (Curculionidae sensu lato) of South America (Coleoptera: Curculionoidea)". Memoirs of the American Entomological Institute. 39: 1–563.
^O’Brien, C.W.; Wibmer, G.J. (1982). "Annotated checklist of the weevils (Curculionidae sensu lato) of North America, Central America, and the West Indies (Coleoptera: Curculionoidea)". Memoirs of the American Entomological Institute. 34: 1–382.