The determination and relationship of four coexisting paramphistomes in perspective of integrative taxonomic investigation.

Co-infections with Orthocoelium species and other paramphistomes were found in different ruminant hosts from two provinces of Thailand. Whilst O. parvipapillatum coexisted with Paramphistomum epiclitum in the same cattle (Bos taurus) from Pathum Thani Province, Thailand, O. dicranocoelium and Fischoederius elongatus were found in water buffalo (Bubalus bubalis) from Chiang Mai Province. Morphological, histological, and tegumental surface features of both Orthocoelium species were intensively investigated for species differentiation. Statistical analysis of eight morphometric ratios presented morphological differences for three paramphistomes in the Paramphistomidae family and some relationships among paramphistomes in different definitive hosts. The genetic relationships of the co-infecting paramphistomes were investigated using p-distance and phylogenetic tree analyses. Genetic variations in the Orthocoelium co-infecting paramphistomes, P. epiclitum and F. elongatus, were calculated and compared to DNA sequence alignments based on internal transcribed spacer 2 (ITS2) and cytochrome c oxidase subunit I (COI) DNA markers. In addition, the phylogenetic tree constructions from both DNA markers and their concatenated sequence (ITS2 + COI) were used for species confirmation and the presentation of genetic relationships between co-infecting paramphistomes and other paramphistomes. This study improves the basic taxonomical description and understanding of parasite-parasite and host-parasite interactions from the perspectives of morpho-histological, morphometric, and genetic variation in co-infecting paramphistomes and Orthocoelium species in different hosts.