Intraspecific variation of Haematoloechus floedae Harwood, 1932 (Digenea: Plagiorchiidae), from Rana spp. in North and Central America.

Haematoloechus floedae was originally described from the lungs of Rana catesbeiana in Texas, and later reported in Florida, in the United States. It was proposed to be synonymous with H. breviplexus, H. parviplexus, and H. varioplexus. We obtained specimens of H. floedae from Rana brownorum and R. vaillanti in Yucatán, Mexico; R. cf. forreri and R. taylori in Guanacaste, Costa Rica; and R. catesbeiana in Georgia and California. Some specimens were processed for morphological study; sequences of the 28S of the rDNA and the mitochondrial COI were obtained from several specimens of each population. Phylogenetic analysis of molecular data indicates studied populations constitute a single taxon, different from H. varioplexus, H. breviplexus, and H. parviplexus. Some morphological characters remain constant among populations of H. floedae, and are useful for differentiating this species. These include the oral sucker-pharynx ratio, oral sucker-ventral sucker ratio, ovary and testes shape, extension of uterine longitudinal loops, and extension of vitelline follicles (in fully developed worms). Sequence homogeneity among populations of H. floedae suggests a recent spread, perhaps due to the introduction of R. catesbeiana for culture to the western United States, southeast Mexico, and Costa Rica.