Molecular and Morphological Evidence for Potentially Novel Species of Taenia and Mesocestoides in Corsac Foxes (Vulpes corsac) from China.

Corsac foxes (Vulpes corsac) mainly distributed in Eastern Asian and Central Asian. To date, there are limited reports on Taenia and Mesocestoides infections in corsac foxes. This study aimed to identify the taxonomic species of 288 tapeworms from two road-killed corsac foxes in northwestern China. Morphological observation indicated that 10 Taenia and 278 Mesocestoides were primarily identified. Furthermore, 25 representative tapeworms were molecularly identified through two genetic markers, the partial cytochrome c oxidase subunit I gene (445bp) and 16S rDNA gene (557bp). Phylogenetic tree analysis indicated that the Mesocestoides species in corsac foxes was the closest to Mesocestoides sp. isolates from red fox in China (accession number: MZ475884) and Kazakhstan (OQ924334), and their identities only shared 89.50% (341/381) and 90.29% (344/381). Taenia species in this study was most closely related to Taenia polyacantha from red foxes in Turkey (PV023876 and PV023884) and Iran (PP658436), sharing 93.93% (418/445) and 94.38% (420/445) identities, respectively. The 16S rDNA sequences showing comparable genetic distances (81.11% (455/561) identity with Mesocestoides sp. from Israel and 93.87% (521/555) with Taenia tianguangfui from China). While a formal taxonomic description is precluded due to the immature nature of the specimens, the loss of rostellar hooks from freeze-thaw cycles, and the limited sample size, our combined morphological and molecular evidence strongly suggests that the Taenia and Mesocestoides isolates found in corsac foxes represent potentially novel species. This study provides a valuable contribution to the understanding of parasite diversity in wildlife and underscores the need for further comprehensive investigations.