Molecular identification and distribution of Dictyocaulus spp. in wild ungulates in Lithuania

Abstract This study aimed to investigate the diversity, prevalence and host specificity of Dictyocaulus lungworms in free-ranging wild ungulates in Lithuania using morphological and molecular approaches. A total of 129 individuals representing 4 host species (red deer, roe deer, moose and European bison) were examined. Four Dictyocaulus species were identified: D. cervi, D. skrjabini, D. capreolus and D. viviparus bisontis . Infection parameters varied markedly among host species. Red deer showed the highest prevalence and parasite diversity, whereas European bison exhibited low prevalence but relatively high infection intensity. Moose displayed intermediate infection levels with a high proportion of co-infections, while roe deer were infected exclusively with the host-specific species D. capreolus . Co-infections involving multiple Dictyocaulus species were common in cervids, indicating complex transmission dynamics. Molecular analyses based on mitochondrial ( cox1 ) and nuclear ( SSU rDNA ) markers confirmed species identification and revealed clear genetic differentiation among taxa. Phylogenetic incongruences between markers suggest potentially complex evolutionary relationships, possibly influenced by co-infections and host overlap. These findings provide the first comprehensive insight into Dictyocaulus infections in wild ungulates in Lithuania and highlight the importance of combining morphological and molecular methods for accurate parasite identification. The results contribute to a better understanding of lungworm epidemiology and host–parasite interactions in wildlife and emphasize the need for improved surveillance strategies.