Mitochondrial (mt) DNA has been useful in revealing the phylogenetic relationship of eukaryotic organisms including flatworms. Therefore, the use of mitogenomic data for the comparative and phylogenetic purposes is needed for those families of digenetic trematodes for which the mitogenomic data are still missing. Molecular data with sufficiently rich informative characters that can better resolve species identification, discrimination, and membership in different genera is also required for members of some morphologically difficult families of trematodes bearing few autapomorphic characters among its members. Here, the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) and the complete mt genome of the trematode Uvitellina sp. (Cyclocoelidae: Haematotrephinae) was determined and annotated. The mt genome of this avian trematode is 14,217 bp in length, containing 36 genes plus a single non-coding region. The ITS rDNA sequences were used for the pairwise sequence comparison of Uvitellina sp. with European cyclocoelid species, and the mitochondrial 12 protein-coding genes (PCGs) and two ribosomal RNA genes were used to evaluate the position of the family within selected trematodes. The ITS rDNA analysis of Uvitellina sp. showed less nucleotide differences with Hyptiasmus oculeus (16.77%) than with other European cyclocoelids (18.63-23.58%). The Bayesian inference (BI) analysis using the 12 mt PCGs and two rRNA genes supported the placement of the family Cyclocoelidae within the superfamily Echinostomatoidea (Plagiorchiida: Echinostmata). The availability of the mt genome sequences of Uvitellina sp. provides a novel resource of molecular markers for phylogenetic studies of Cyclocoelidae and other trematodes.

3rd Faculty of Medicine Charles University 100 00 Prague Czech Republic

Department of Zoology University of Swabi Khyber Pakhtunkhwa Pakistan

Jiangsu Co innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses Yangzhou University College of Veterinary Medicine Yangzhou Jiangsu Province 225009 People's Republic of China

State Key Laboratory of Veterinary Etiological Biology Key Laboratory of Veterinary Parasitology of Gansu Province Lanzhou Veterinary Research Institute Chinese Academy of Agricultural Sciences Lanzhou Gansu Province 730046 People's Republic of China

State Key Laboratory of Veterinary Etiological Biology Key Laboratory of Veterinary Parasitology of Gansu Province Lanzhou Veterinary Research Institute Chinese Academy of Agricultural Sciences Lanzhou Gansu Province 730046 People's Republic of China Jiangsu Co innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses Yangzhou University College of Veterinary Medicine Yangzhou Jiangsu Province 225009 People's Republic of China

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