Reorganisation of the turtle blood fluke genera Hapalotrema and Learedius (Trematoda: Hapalotrematidae), with the proposal of two new genera, a new species, and comments on population structure.

Hapalotrematid trematodes are by far the most commonly reported species of blood flukes infecting marine turtles. Species of this family infect a wide range of organs in their hosts, but are most often reported from the heart and associated major blood vessels. Although commonly encountered, there remain issues surrounding the genus-level characterisation within the family. Previous phylogenetic studies have shown that the genera Hapalotrema Looss, 1899 and Learedius Price, 1934 do not adequately represent the relationships of their associated species, with species of Learedius routinely falling among those of Hapalotrema. Here, we use morphological and multi-locus molecular data to resolve the paraphyly of Hapalotrema by proposing two new genera. Additionally, we describe a new species, examine the population structure hapalotrematids with cox1 mtDNA data, and report the first infection of an adult turtle blood fluke from the olive ridley sea turtle. We show that the level of genetic variation differs significantly between species, and multiple populations of hapalotrematid morphospecies exist along the coast of southeast Queensland, Australia. Finally, the phylogenetic affinities of Amphiorchis solus (Simha & Chattopadhyaya, 1970) Platt, 2002 in relation to the other species of the Hapalotrematidae is elucidated.