First record of Culicoides oxystoma Kieffer and diversity of species within the Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) biting midges in Senegal

Abstract

The Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) is distributed throughout Africa to northern Asia and Australasia and includes several potential vector species of livestock pathogens. The taxonomy of the species belonging to this species group is confounded by the wide geographical distribution and morphological variation exhibited by many species. In this work, morphological and molecular approaches were combined to assess the taxonomic validity of the species and morphological variants of the Schultzei group found in Senegal by comparing their genetic diversity with that of specimens from other geographical regions. The species list for Senegal was updated with four species: Culicoides kingi, C. oxystoma, C. enderleini and C. nevilli being recorded. This is the first record of C. oxystoma from Africa south of Sahara, and its genetic relationship with samples from Israel, Japan and Australia is presented. This work provides a basis for ecological studies of the seasonal and spatial dynamics of species of this species group that will contribute to better understanding of the epidemiology of the viruses they transmit.

Figure 1. Female wing pattern and male genitalia of the Schultzei species group collected in Senegal (samples from the study and Cornet’s collection) and South Africa.

The slide reference number refers to the Cornet collection reference numbers .

Figure 2. Location of the study sites in Senegal and abundance of species from the Schultzei group.

Figure 3. Variation in the wing patterns of C. subschultzei and C. oxystoma found in Senegal: Culicoides subschultzei typical form (A), Culicoides oxystoma typical form (B) and morphological variants: absence of pale spots in the second median cell (C) and presence of two pale spots in cubital cell (D).

Figure 4. Phylogenetic analysis of species of the Schultzei group using COI sequence data.

The topology shows Bayesian inference tree using program MrBayes. Culicoides imicola was designated as an outgroup taxon. Numbers indicate bootstrap values from ML (bottom) analyses, and posterior probabilities from Bayesian analysis (top). Only bootstrap values >60% and Bayesian posterior probabilities >0.5 are shown. Branch lengths represent nucleotide substitutions per site.