Morphological and genetic characterizations of Avitellina tapeworms from domestic ruminants in Senegal: An evidence of specificity among sheep and cattle host.

Avitellina tapeworms are common intestinal parasites of ruminants with a worldwide distribution. In Senegal, only Avitellina centripunctata tapeworm has been reported to date, and genetic diversity was previously confirmed by enzymatic analysis. This study aims to clarify the diversity of Avitellina tapeworms isolated from sheep and cattle in Senegal. In total, 613 adult Avitellina tapeworms were collected from sheep and cattle. Morphological analysis by the light microscopy and scanning electron microscopy identified three Avitellina "morphospecies": A. centripunctata and Avitellina sp.2 were detected in sheep while Avitellina sp.3 was identified in cattle. Molecular phylogenetic analysis based on the complete mitochondrial cytochrome c oxidase subunit 1 gene (cox1) sequences revealed that 101 Avitellina tapeworms were divided into 54 haplotypes grouped into three clades, of which two were specific to sheep and one specific to cattle. Three morphospecies corresponded to each of three clades and the maximum pairwise divergence among the clades ranged from 9.7 to 18.5% in cox1. The present study demonstrates the unexpected diversity of Avitellina tapeworms in domestic ruminants, and emphasize the necessity of re-evaluation of the taxonomy of the genus.