Avian malaria is a widespread vector-borne disease caused by haemosporidian parasites that can negatively affect avian survival, reproduction, and populati

The Ceratopogonidae (Diptera, Nematocera) is a highly diverse family of insects inhabiting a wide range of habitat types that is only absent from polar regions and remote islands. Despite this broad diversity, scientific knowledge of this family remains incomplete, including the genus Leptoconops Skuse, 1889. Although several Leptoconops species have been reported from Europe, no detailed study has yet been conducted to resolve the taxonomy of this genus and clarify species occurrence. Here, the first comprehensive study of Leptoconops diversity in southwest Spain is provided based on extensive sampling conducted in 2023–2024. In total, eight Leptoconops species were collected using carbon-dioxide suction traps: Leptoconops (Leptoconops) noei Clastrier & Coluzzi, 1973, Leptoconops (Leptoconops) irritans Noé, 1905, and four new species: Leptoconops (Leptoconops) nigrithorax González & Tanase, sp. nov ., Leptoconops (Leptoconops) triangularis González & Tanase, sp. nov., Leptoconops (Leptoconops) pseudoirritans González & Tanase, sp. nov ., and Leptoconops (Leptoconops) communis González & Tanase, sp. nov . Additionally, Leptoconops (Leptoconops) bidentatus Gutsevich, 1960, was recorded for the first time from the Iberian Peninsula. One species of the subgenus Holoconops : Leptoconops (Holoconops) cf. kerteszi Kieffer, 1908, was also identified. Molecular support for the morphological identification is provided using COX1 barcode sequences. A brief review of Leptoconops species occurrence in Europe is also included, with detailed morphological descriptions supported by high-quality images of the newly described species, and a complete identification key for dry-preserved and slide-mounted adult females of the subgenus L. ( Leptoconops ).