Background
Culicoides obsoletus is an abundant and widely distributed Holarctic biting midge species, involved in the transmission of bluetongue virus (BTV) and Schmallenberg virus (SBV) to wild and domestic ruminants. Females of this vector species are often reported jointly with two morphologically very close species, C. scoticus and C. montanus, forming the Obsoletus/Scoticus Complex. Recently, cryptic diversity within C. obsoletus was reported in geographically distant sites. Clear delineation of species and characterization of genetic variability is mandatory to revise their taxonomic status and assess the vector role of each taxonomic entity. Our objectives were to characterize and map the cryptic diversity within the Obsoletus/Scoticus Complex.
Methods
Portion of the cox1 mitochondrial gene of 3763 individuals belonging to the Obsoletus/Scoticus Complex was sequenced. Populations from 20 countries along a Palaearctic Mediterranean transect covering Scandinavia to Canary islands (North to South) and Canary islands to Turkey (West to East) were included. Genetic diversity based on cox1 barcoding was supported by 16S rDNA mitochondrial gene sequences and a gene coding for ribosomal 28S rDNA. Species delimitation using a multi-marker methodology was used to revise the current taxonomic scheme of the Obsoletus/Scoticus Complex.
Results
Our analysis showed the existence of three phylogenetic clades (C. obsoletus clade O2, C. obsoletus clade dark and one not yet named and identified) within C. obsoletus. These analyses also revealed two intra-specific clades within C. scoticus and raised questions about the taxonomic status of C. montanus.
Conclusions
To our knowledge, our study provides the first genetic characterization of the Obsoletus/Scoticus Complex on a large geographical scale and allows a revision of the current taxonomic classification for an important group of vector species of livestock viruses in the Palaearctic region.
A taxonomic study of the marine diatoms belongjng to the Suborder Araphidineae from the southwestern coast of Puerto Rico is reported in this paper. Sixteen genera and thirty-one species were observed. A new genus, Florella, and a new species, F. portoricensis, are described. Five taxa are new records for Puerto Rico and two for the Caribbean Sea. Most of the encountered species are cosmopolitan forms in temperate-tropical neritic waters.
A taxonomic study of the marine diatoms belonging to the family Naviculaceae from the southwestern coast of Puerto Rico is reported in this paper. Three genera, 47 species, four varieties and one form were observed. Thirteen of these taxa are new records for Puerto Rico and seventeen are new for the Caribbean Sea. All of the species are neritic and most are pantropical and cosmopolitan in tropical temperate waters.30. Yohn and Gibson (l981) 31. Vohn and Gibson (1982a) 32. Yohn and Gibson (1982b)
A taxonomic study on the marine diatoms from the southwestern coast of Puerto Rico is reported in this paper.One family, Chaetoceraceae, of the suborder Biddulphiineae, with 2 genera, 31 species and l variety were observed. Eight of these taxa had never been reported from the coast of Puerto Rico and one is new for Puerto Rico and the Caribbean Sea.Most of the identified species are cosmopolitan in temperate-tropical waters and neritic.
Culicoides (Diptera: Ceratopogonidae) are vectors of pathogens that affect wildlife, livestock and, occasionally, humans. Culicoides imicola (Kieffer, 1913) is considered to be the main vector of the pathogens that cause bluetongue disease (BT) and African horse sickness (AHS) in southern Europe. The study of blood-feeding patterns in Culicoides is an essential step towards understanding the epidemiology of these pathogens. Molecular tools that increase the accuracy and sensitivity of traditional methods have been developed to identify the hosts of potential insect vectors. However, to the present group's knowledge, molecular studies that identify the hosts of C. imicola in Europe are lacking. The present study genetically characterizes the barcoding region of C. imicola trapped on farms in southern Spain and identifies its vertebrate hosts in the area. The report also reviews available information on the blood-feeding patterns of C. imicola worldwide. Culicoides imicola from Spain feed on blood of six mammals that include species known to be hosts of the BT and AHS viruses. This study provides evidence of the importance of livestock as sources of bloodmeals for C. imicola and the relevance of this species in the transmission of BT and AHS viruses in Europe.
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