Characterization of the complete mitochondrial genome and phylogenetic analyses of Euparadistomum sp. (Trematoda: Dicrocoeliidae) from the Bengal slow loris, Nycticebus bengalensis.

Abstract

The Dicrocoeliid trematodes of genus Euparadistomum are common parasites in the gallbladder of diverse vertebrate hosts and displays significant morphological diversity. However, molecular data for this genus remain scarce, and no complete mitochondrial (mt) genome had previously been available. In the present study, the complete mt genome of Euparadistomum sp. from the bile ducts of Bengal slow loris in Changsha Ecological Zoo was sequenced, assembled, annotated and analyzed. The complete mt genome of Euparadistomum sp. is 16,167 bp in length and contained 12 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and one non-coding region (NCR). Compared with other published mt genomes of Dicrocoeliidae, the relative positions of tRNA-Gly and tRNA-Glu were exchanged in Euparadistomum sp. Phylogenetic analysis showed that Euparadistomum sp. as a sister lineage to the remaining sampled dicrocoeliids, supporting its placement within Dicrocoeliidae. Additional analyses based on partial cox1 sequences, including pairwise genetic distance estimation and phylogenetic inference with available dicrocoeliid sequences, further supported the generic assignment of the specimen to Euparadistomum . This study provides the first complete mt genome for Euparadistomum and adds molecular evidence for the occurrence of this genus in China.