Jumping continents and major host lineages: phylogeny and diversity of the enigmatic Cryptotropidae (Platyhelminthes: Digenea)

Members of several genera in the digenean superfamily Microphalloidea, namely Renschetrema, Rohdetrema, Cryptotropa, Cephalouterina and Pseudocryptotropa, are characterized by an unusual dorsal position of the genital atrium. In the absence of phylogenetic data, their systematic position has been unstable. In the most recent taxonomic revision of the Microphalloidea, they were housed in three different families. We studied the morphology and obtained DNA sequences of several microphallolideans with a dorsal genital pore, collected from vertebrates in Southeast Asia and South America. We used sequences of the nuclear 28S gene to infer a superfamily-level phylogeny and sequences of the mitochondrial cox1 gene for family-level phylogeny and species-level comparisons. Based on the combination of molecular phylogenetic data and morphological features, we restore the Cryptotropidae and synonymize the Renschetrematidae with the Cryptotropidae. We erect new genera Paracryptotropagen. nov. and Armadoatriumgen. nov., provide amended diagnoses of the Cryptotropidae and Renschetrema and provide keys to the identification of genera within the family. We resurrect the genus Novetrema, previously synonymized with Pseudocryptotropa, and remove Renschetrema indicum from Renschetrema. We describe four new species from lizards in Vietnam and birds in the Philippines and Peru. The unique morphological features and unusually broad host associations and geographical distributions of cryptotropids are discussed.