Revision of the systematics of the Polystomoidinae (Platyhelminthes, Monogenea, Polystomatidae) with redefinition of Polystomoides Ward, 1917 and Uteropolystomoides Tinsley, 2017

Polystomatids are platyhelminth parasites that infect mainly amphibians and freshwater turtles. For more than seven decades, chelonian polystomes were classified into three genera according to the number of hamuli, i.e. absent for Neopolystoma, one pair for Polystomoidella and two pairs for Polystomoides. Following re-examination of morphological characters, seven new genera were erected the past six years, namely Apaloneotrema, Aussietrema, Fornixtrema, Manotrema, Pleurodirotrema, Uropolystomoides and Uteropolystomoides. However, the polyphyly of Neopolystoma and Polystomoides on the one hand, and the nested position of Uteropolystomoides within a clade encompassing all Neopolystoma and Polystomoides spp. on the other, still raised questions about the validity of these genera. We therefore re-examined several types, paratypes and voucher specimens, and investigated the molecular phylogeny of polystomes sampled from the oral cavity of North American turtles to re-evaluate their systematic status. We show that all Polystomoides Ward, 1917, sensu Du Preez et al., 2022, Neopolystoma Price, 1939, sensu Du Preez et al., 2022 and Uteropolystomoides Tinsley, 2017 species, display vaginae that are peripheral and extend well beyond the intestine. We thus reassign all species of the clade to Polystomoides and propose nine new combinations; however, although Uteropolystomoides is nested within this clade, based on its unique morphological features, we propose to keep it as a valid taxon. Polystomoides as redefined herein groups all polystome species infecting either the oral cavity or the urinary bladder of cryptodires, with peripheral vaginae and with or without two pairs of small hamuli. Uteropolystomoides nelsoni (Du Preez & Van Rooyen 2015), originally described from Pseudemys nelsoni Carr is now regarded as Uteropolystomoides multifalx (Stunkard, 1924) n. comb. infecting three distinct Pseudemys species of North America

Parasite host-switching from the invasive American red-eared slider, Trachemys scripta elegans, to the native Mediterranean pond turtle, Mauremys leprosa, in natural environments

International audienceThe red-eared slider turtle, Trachemys scripta elegans, is among the most over-exploited animals and is still exported annually from the USA all over the world. Once introduced into its new environment, feral populations may arise and pose threats to local biodiversity and ecosystem functioning. In France, it is in fact considered as a risk for the Mediterranean pond turtle, Mauremys leprosa, and the European pond turtle, Emys orbicularis, as they may compete for resources and habitat. Freshwater turtles are also host to a variety of parasites including protozoans and helminths. When introduced turtles escape, parasites may spread to native species. The objective of this study was to document the extent of platyhelminth invasions from T. s. elegans to natural M. leprosa populations in northern Spain and southern France and to evaluate the risks that parasite host-switching may pose on indigenous freshwater turtle species. From DNA barcoding analysis based on the sequencing of the Cytochrome c Oxidase I gene, the Bayesian tree and p-distance comparisons of closely related haplotypes revealed a greater polystome richness within M. leprosa than expected, suggesting that host switching may take place in natural environments. Because these parasites most typically infest American turtles like Chrysemys picta marginata and Graptemys pseudogeographica in their natural home range and because parasites were also found within T. s. elegans feral populations, it is suggested that the red-eared slider would serve as a carrier for a variety of not strictly host-specific polystomes that are transmitted to M. leprosa throughout the south of France. The global trade in freshwater turtles thus provides opportunity for parasites to be transported to new destinations which could impact the physiology, behavior and survival of native turtle species

Morphological and Molecular Evolution Are Not Linked in Lamellodiscus (Plathyhelminthes, Monogenea)

Lamellodiscus Johnston & Tiegs 1922 (Monogenea, Diplectanidae) is a genus of common parasites on the gills of sparid fishes. Here we show that this genus is probably undergoing a fast molecular diversification, as reflected by the important genetic variability observed within three molecular markers (partial nuclear 18S rDNA, Internal Transcribed Spacer 1, and mitonchondrial Cytochrome Oxidase I). Using an updated phylogeny of this genus, we show that molecular and morphological evolution are weakly correlated, and that most of the morphologically defined taxonomical units are not consistent with the molecular data. We suggest that Lamellodiscus morphology is probably constrained by strong environmental (host-induced) pressure, and discuss why this result can apply to other taxa. Genetic variability within nuclear 18S and mitochondrial COI genes are compared for several monogenean genera, as this measure may reflect the level of diversification within a genus. Overall our results suggest that cryptic speciation events may occur within Lamellodiscus, and discuss the links between morphological and molecular evolution

Conservation animale (utilisation des parasites comme marqueurs de l écologie évolutive des amphibiens)

PERPIGNAN-BU Sciences (661362101) / SudocSudocFranceF

Eye to eye: classification of conjunctival sac polystomes (Monogenea: Polystomatidae) revisited with the description of three new genera Apaloneotrema n. g., Aussietrema n. g. and Fornixtrema n. g.

Polystomes (Monogenea: Polystomatidae) of freshwater turtles are currently represented by five genera, namely Neopolystoma, Polystomoides, Polystomoidella, Uropolystomoides and Uteropolystomoides. These parasites can infect the urinary, oral and/or the conjunctival sac systems of their hosts, showing strict site specificity. A recent phylogenetic study showed that the two most diverse genera within chelonian polystomes, i.e. Neopolystoma and Polystomoides, are not monophyletic. Furthermore, polystomes infecting the conjunctival sacs of their host, except for one species, formed a robust lineage. A fusiform egg shape has been reported for conjunctival sac polystomes and it was assumed that this characteristic could be a good character for the systematics of polystomes. Our objective in the present work was, therefore, to study more in depth the morphology of polystomes collected from the conjunctival sacs of chelonians to find characters defining a putative new genus. To achieve this objective, more specimens were collected in 2018 and 2019 from turtles sampled in North Carolina and Florida (USA) to extend taxon sampling for the phylogenetic analysis. Morphological characters of relevant polystome specimens were re-examined from several collections from Asia, Australia, Europe, South Africa, South America and North America. Based on a Bayesian tree inferred from the analysis of four concatenated genes, namely 12S, 18S, 28S and COI, polystomes found in the conjunctival sacs were grouped in three distinct lineages, the first one including a single species infecting an Australian pleurodire turtle; the second one including eleven species infecting cryptodire turtles of South America, North America and Asia; and the last one including a single species infecting a softshell cryptodire turtle of North America. Based on observations of live specimens by Dr. Sylvie Pichelin and our morphological analysis, the conjunctival sac polystomes from Australian turtles are small, cannot extend their body significantly, have a spherical ovary and egg, have a large genital bulb and possess latero-ventral vaginae at the level of the testis. Based on observations of live specimens and morphological analysis of whole mounted specimens, polystomes of the second lineage share the following morphological characteristics: the ability to stretch out and double their length, a long oval ovary, a separate egg-cell-maturation-chamber, fusiform to diamond-shaped eggs with acute tips, small genital bulb and vaginae peripheral on the side of the body at the level of the testis. The polystome species of the third lineage occupies a basal position, has the ability to stretch out and possess an elongated ovary, a large fusiform egg with rounded tips, a small genital bulb and small latero-ventral vaginae at the level of the ovary. These three distinct conjunctival sac polystome lineages are herein described as separate new genera, Aussietrema, Fornixtrema and Apaloneotrema, respectivel

First record of viviparity in polystomatid flatworms (Monogenea: Polystomatidae) with the description of two new species of Madapolystoma from the Madagascan anuran hosts Blommersia domerguei and Mantella expectata

International audienceTwo frog species, Blommersia domerguei and Mantella expectata, are reported as hosts for new species of Madapolystoma. Phylogenetic analyses and genetic divergences observed in the genus supported the distinction of two morphotypes infesting selectively each host species and morphological investigation combining marginal hooklet morphometrics, genital spine number and measurements further showed that polystomes from the two host species differed from each other and from all other known polystomes. Madapolystoma magnahami n. sp. and Madapolystoma isaloensis n. sp. are therefore described as two new species. Advanced in utero development was illustrated in both polystome species following the observation of well developed hamuli and two pairs of haptoral suckers in developing embryos. Inside some of these in utero embryos a F2 generation embryo was also observed. This is the first report of true viviparity among polystomatid flatworms

Lessons from parasitic flatworms about evolution and historical biogeography of their vertebrate hosts

http://dx.doi.org/10.1016/j.crvi.2008.08.01

Oxidative stress biomarkers in the Mediterranean pond turtle ( Mauremys leprosa ) reveal contrasted aquatic environments in Southern France

International audienceIncreasing anthropogenic activities, like agricultural practices, constitute the main causes of the loss ofwater quality and disruption of freshwater ecosystems. High concentrations of pesticides, as shownunder experimental conditions, can indeed impact freshwater animals. In Southern France, especially inthe Pyrenees-Orientales department, because agricultural activities are mainly based on fruit crops andvineyards, glyphosate and AMPA were detected in some watercourses. Thereby we investigated the effectsof degraded waters on the physiology of the endemic endangered freshwater species, namely theMediterranean pond turtle Mauremys leprosa, in contrasted environments along the same rivers on theone hand and between different rivers on the other. We measured the activity and gene expression oftwo enzymes involved in the oxidative detoxification processes, namely the Catalase and the Superoxidedismutase. We showed significant variations in the Catalase gene expression and activity within turtlesof the Fosseille River depending of their location, i.e. upstream or downstream of the wastewatertreatment plants (WTP). Because agricultural environments are similar all along this river, they can no belonger considered as the unique source of turtle stress. The processed waters discharged by the WTP

Alternative development in polystoma gallieni (platyhelminthes, monogenea) and life cycle evolution

Considering the addition of intermediate transmission steps during life cycle evolution, developmental plasticity, canalization forces and inherited parental effect must be invoked to explain new host colonization. Unfortunately, there is a lack of experimental procedures and relevant models to explore the adaptive value of alternative developmental phenotypes during life cycle evolution. However, within the monogeneans that are characterized by a direct life cycle, an extension of the transmission strategy of amphibian parasites has been reported within species of Polystoma and Metapolystoma (Polyopisthocotylea; Polystomatidae). In this study, we tested whether the infection success of Polystoma gallieni within tadpoles of its specific host, the Stripeless Tree Frog Hyla meridionalis, differs depending on the parental origin of the oncomiracidium. An increase in the infection success of the parasitic larvae when exposed to the same experimental conditions as their parents was expected as an adaptive pattern of non-genetic inherited information. Twice as many parasites were actually recorded from tadpoles infected with oncomiracidia hatching from eggs of the bladder parental phenotype (1.63 ± 0.82 parasites per host) than from tadpoles infected with oncomiracidia hatching from eggs of the branchial parental phenotype (0.83 ± 0.64 parasites per host). Because in natural environments the alternation of the two phenotypes is likely to occur due to the ecology of its host, the differential infection success within young tadpoles could have an adaptive value that favors the parasite transmission over time.http://www.journals.elsevier.com/experimental-parasitology