Integrating morphology and genetics to resolve the first reptilian liolopid life cycle in Africa, <i>Paraharmotrema karinganiense</i> (Digenea: Liolopidae)

The Liolopidae (Diplostomoidea) are a small family of digeneans that parasitize reptiles and amphibians as adults. Knowledge of intermediate hosts in this family remains scarce, leaving a major gap in the understanding of liolopid biology. To date, the only fully elucidated life cycle is that of <i>Liolope copulans</i> Cohn 1902, a species infecting Asian salamanders, with no other cercarial or metacercarial stages known. This study aimed to identify potential intermediate hosts for <i>Paraharmotrema karinganiense</i>, found in several chelonian species from southeastern Mozambique and South Africa. African apple snails of the genus <i>Lanistes</i> and <i>Nothobranchius</i> killifish were sampled from temporary pools in Karingani Game Reserve, southern Mozambique. Snails were screened over 9 months for cercarial shedding, and encapsulated metacercariae recovered from the spotted killifish (<i>N. orthonotus</i>, Peters) (Cyprinodontiformes: Nothobranchiidae) were excysted for morphological and molecular analyses. Fork-tailed cercariae from <i>Lanistes</i> sp. and 1 metacercaria found in the spotted killifish were genetically identical to the adult of <i>P. karinganiense</i>. This study provides the second documented life cycle of a liolopid trematode and presents the first life cycle for the family based on natural infections, being the first completely documented life cycle for freshwater trematodes from southern Africa. This linkage of larval and adult specimens signifies the importance of <i>Nothobranchius</i> killifish as intermediate hosts as well providing insight in parasite transmission dynamics within temporary aquatic ecosystems.