Using Combined Morphological, Allometric and Molecular Approaches to Identify Species of the Genus Raillietiella (Pentastomida)

Taxonomic studies of parasites can be severely compromised if the host species affects parasite morphology; an uncritical analysis might recognize multiple taxa simply because of phenotypically plastic responses of parasite morphology to host physiology. Pentastomids of the genus Raillietiella are endoparasitic crustaceans primarily infecting the respiratory system of carnivorous reptiles, but also recorded from bufonid anurans. The delineation of pentastomids at the generic level is clear, but the taxonomic status of many species is not. We collected raillietiellids from lungs of the invasive cane toad (Rhinella marina), the invasive Asian house gecko (Hemidactylus frenatus), and a native tree frog (Litoria caerulea) in tropical Australia, and employed a combination of genetic analyses, and traditional and novel morphological methods to clarify their identity. Conventional analyses of parasite morphology (which focus on raw values of morphological traits) revealed two discrete clusters in terms of pentastome hook size, implying two different species of pentastomes: one from toads and a tree frog (Raillietiella indica) and another from lizards (Raillietiella frenatus). However, these clusters disappeared in allometric analyses that took pentastome body size into account, suggesting that only a single pentastome taxon may be involved. Our molecular data revealed no genetic differences between parasites in toads versus lizards, confirming that there was only one species: R. frenatus. This pentastome (previously known only from lizards) clearly is also capable of maturing in anurans. Our analyses show that the morphological features used in pentastomid taxonomy change as the parasite transitions through developmental stages in the definitive host. To facilitate valid descriptions of new species of pentastomes, future taxonomic work should include both morphological measurements (incorporating quantitative measures of body size and hook bluntness) and molecular data

Helminth parasites of Silurana tropicalis from the Okomu National Park, Edo State, Nigeria

Silurana tropicalis, the edible clawed-frog, collected from the Okomu National Park, Edo State, Nigeria, was examined for helminth parasitic infections. From 142 specimens collected, ten endo-helminth parasites spread across four classes were recovered. These included Cestoda: Cephalochlamys compactus and the cyst of a proteocephalidcestode; Trematoda: Mesocoelium monodi, Nematoda: Batrachocamallanus siluranae, Camallanus siluranae, Cosmocerca ornata, an unidentified oxyurid nematode and encysted larvae of an unidentified nematode; Acanthocephala: Centrorynchus sp. occurred only as cysthacanth. Also encountered were cysts carrying a mixed infection nematode/proteocephalid larvae Thus, Silurana tropicalis collected from the protected rainforest haboured more parasites than those of its counterpart from the derived-savanna of Edo State. Some parasites of S. tropicalis, including C. compactus, the encysted-proteocephalidcestode and C. ornata also occur in other pipid anurans. However, some other helminths such as the unidentified oxyurid nematode, the encysted larval nematodes, encysted mixed infection and the cysthcanths of Centrorynchus have no previous record in other members of the Pipidae. The presence of encysted parasites attached to some organs of the viscera is indicative of S. tropicalis having a role as a paratenic or transport host. The sharing of a common cyst by two parasites belonging to different classes is a novel parasitic adaptation ensuring an efficient delivery of multiple infections to their hosts.Keywords: helminth parasites, Siluranatropicalis, rainforest, parasitic adaptations

FIGURE 1 in A redescription of Polystoma africanum Szidat, 1932 (Monogenea: Polystomatidae)

FIGURE 1. Partial map of Africa with Nigeria enlarged and Edo State where specimens were collected in grey. Type locality of Polystoma africanum marked as a black dot and other known localities as grey dots

Ecological Scenarios and Parasite Diversity in Anurans of West Africa: A Review

This paper is a survey of the parasite diversity, prevalence and infection intensity in anurans in diverse ecological settings in West Africa. The settings included natural habitats (rainforests, freshwater creeks, Guinea and Sudan savannas), monoculture plantations (cocoa, cotton and oil palm), urbanized and urbanizing rainforest biotopes and polluted environments due to oil industry activities. The natural habitats had higher amphibian species diversity, moderate parasite prevalence and low infection intensity, showing a balance in the host/parasite relationship. These habitats yielded most of the monogeneans, among which were new species. The freshwater creek biotope had low amphibian diversity, but hosts from this environment harbored several parasite taxa, a situation attributed to a prolonged wet season, high environmental humidity and persistent breeding pools for insect vectors in this area. The monoculture plantations were characterized by high parasite prevalence but lower infection intensity. For example, in the Pendjari Biosphere Reserve in Bénin Republic, the Agricultural Zone (AZ) had higher parasite prevalence values, while the National Park (NP) and Buffer Zone (BZ) had higher infection intensities. Higher prevalence was attributed to the single or combined effects of vector population explosion, immune-suppression by agrochemicals, nutrient enrichment and eutrophication from fertilizer use. The lower infection intensity was attributed to the inhibitory effect of the pesticide-contaminated environment on the free-living larval stages of parasites. The adverse effect of pesticide contamination was also evident in the lower infection intensity recorded in the anurans from the cocoa plantations at Ugboke in comparison to those from the pesticide-free village settlement. Urbanization reduced host diversity and numbers and increased the vector population, resulting in unusually high parasite prevalence and infection intensities at Diobu and Port Harcourt and high prevalence recorded for Ophidascaris larvae in the anurans of Evbuabogun. Oil pollution in the mangrove community reduced both host and parasite diversity; infection intensity was also low due to the adverse conditions confronting free-living stages of parasites in their development milieu. The high prevalence values obtained for monogeneans (Polystoma spp.) in Ptychadena spp. from Ogoniland was presumed to have resulted from host tadpole sequestration and exposure to high oncomiracidia burden in the few hospitable ponds. Also reviewed is the phenomenon of amphibian paratenism, a strategy on which many helminth parasites rely on for their trophic transmission to their definitive hosts