Phylogenetic interrelationships among 13 taxa of Tylodelphys and Austrodiplostomum spp. based on Bayesian inference analysis of partial 28S rRNA gene sequences. Bayesian inference posterior probability values lower than 80% are not shown. The new sequences generated in this study are indicated in bold. The scale bar indicates the number of substitutions per site. GenBank accession numbers are provided after the names of species. References to origins of species numbering/naming systems are provided in parentheses after GenBank accession numbers followed by the biogeographical realms where specimens were collected, life stages of isolate and families of definitive hosts (for adult isolates and larvae molecularly matched to adult forms). Abbreviations for references to the original designations of species-level lineages: L, Locke et al. (2010a, b; 2015); R, Rosser et al. (2016a). The previously accepted/published names are provided in parentheses after GenBank accession numbers. Abbreviations for biogeographical realms: Nea, Nearctic realm; Neo, Neotropical realm; Pal, Palaearctic realm. Abbreviations for life stage: Adu, adult; Cer, cercaria; Met, metacercaria. Abbreviations for families of definitive hosts: Cic, Ciconiidae; Gav, Gaviidae; Pel, Pelecanidae; Pha, Phalacrocoracidae; Pod, Podicipedidae.