Morphological confirmation of the separate species status of Culicoides (Avaritia) nudipalpis Delfinado, 1961 and C. (A.) imicola Kieffer, 1913 (Diptera: Ceratopogonidae).

Ten character states were used to compare five females and two males of two populations of C. nudipalpis from the Philippines and Timor in south-east Asia with 121 females and 167 males of 11 populations of C. imicola collected throughout its Afro-Asiatic range. It is concluded that they are closely related but good species, and together form a subgroup, or species-pair, in the imicola group; currently this Old World group of the subgenus Avaritia comprises seven described species. Culicoides nudipalpis and C. imicola are most reliably separated on the ratio of the length of the proboscis to the height of the head (P/H ratio: 0.66-0.73 in nudipalpis, 0.82-1.02 in imicola). Compared to C. imicola very little is known of the life habits of C. nudipalpis. The latter's close taxonomic relationship to C. imicola, a proven vector of African horse sickness (AHS) and bluetongue (BT), indicates that the capacity of C. nudipalpis to vector these orbiviruses deserves to be investigated.