The study explores the generic limits and systematic position of Leptoschoinus Dejean, 1836, the type genus for a poorly defined family-group name in Baridinae. Species of five nominal genera, generally with a bipartite denticulation on the endophallus but for historical reasons being assigned to different tribes, were examined for consistency and variants of morphological, mostly male-specific, traits. It is concluded that Leptoschoinus accommodates the most basal elements among the studied species, with plesiomorphic traits dominating. The species of PlatyonyxSchönherr, 1826 and LeptocorynusCasey, 1920 are recognized as advanced members of the same clade, not as a divergent branch of a monophyletic Leptoschoinus. OdontocorynusSchönherr, 1844 is considered as the sister group, with its own similarly inconsistent and progressively diversifying suite of apomorphic states. The following new synonymies are proposed: Leptoschoinus and Leptocorynus are placed in synonymy with Platyonyx; Centrinus nobilis Gistel, 1857 and Leptoschoinus quadriguttatus Voss, 1943 are placed in synonymy with Megabaris quadriguttata (Klug, 1829); Platyonyx ornatus griseofasciatusHustache, 1951 is placed in synonymy with P. ornatusSchönherr, 1826; and Polpones sexmaculatusHustache, 1951 is synonymized with Polpones decemmaculatus Bondar, 1945. Leptocorynus longiclava (Champion, 1908) and Leptocorynus tenuiclava (Champion, 1908) are transferred back to Geraeus Pascoe, 1889 (reinstated combinations). Centrinus curtusHustache, 1951, Leptocorynus aspersus (Champion, 1908), Leptocorynus scutatus (Champion, 1908), and Leptoschoinus fucatus (Klug, 1829) are transferred to Platyonyx (new combinations). Platyonyx ornatus diffususHustache, 1951 is promoted to full species rank (new status). Leptoschoinus quadriguttatus Voss is recognized as a junior secondary homonym of M. quadriguttata (Klug) (new homonymy). The subtribe Leptoschoinina Lacordaire, 1865 is transferred from Madarini Jekel, 1865 to Apostasimerini Schönherr, 1844 (new placement). Platyonyx burkei Prena and Platyonyx wecius Prena are described from central Mexico, and Platyonyx hah Prena is described from Panama, Colombia, and Venezuela (all new species). Previous records of Platyonyx fucatus (Klug) from Mexico apply to P. burkei, records from Panama to P. hah, and records from French Guiana probably to P. ornatus.