The double odyssey of Madagascan polystome flatworms leads to new insights on the origins of their amphibian hosts

Abstract

Polystomatid flatworms are parasites of high host specificity, which mainly infect amphibian hosts. Only one polystome species has so far been recorded from Madagascar despite the high species richness and endemicity of amphibians on this island. Out of the 86 screened Malagasy frog species, we recovered polystomes from 25 in the families Ptychadenidae and Mantellidae. Molecular phylogenetic analysis uncovered an unexpected diversity of polystome species belonging to two separate clades: one forming a lineage within the genus Metapolystoma, with one species in Ptychadena and several species in the mantellid host genera Aglyptodactylus and Boophis; and the second corresponding to an undescribed genus that was found in the species of the subfamily Mantellinae in the family Mantellidae. The phylogenetic position of the undescribed genus along with molecular dating suggests that it may have colonized Madagascar in the Late Mesozoic or Early Cainozoic. By contrast, the more recent origin of Metapolystoma in Madagascar at ca 14-2 Myr ago strongly suggests that the ancestors of Ptychadena mascareniensis colonized Madagascar naturally by overseas dispersal, carrying their Metapolystoma parasites. Our findings provide a striking example of how parasite data can supply novel insights into the biogeographic history of their hosts.

Constraining the Deep Origin of Parasitic Flatworms and Host-Interactions with Fossil Evidence

“…Furthermore, molecular studies with greater taxonomic coverage have particularly focused on biomedically or economically important taxa such as Schistosomatidae (Lockyer et al, 2003b;Orélis-Ribeiro et al, 2014) or particular lineages with a high host specificity such as Polystomatidae (Bentz et al, 2001(Bentz et al, , 2006Badets et al, 2011Badets et al, , 2013Héritier et al, 2015). To better Figure 6 Ultrametric tree of neobatrachian polystomes inferred from MULTIDIVTIME (Modified after Verneau et al (2009b).). Calibration points (black rectangles, nodes 1e3) were deduced from historical biogeographical scenarios suggested by Bentz et al (2001Bentz et al ( , 2006 and Badets et al (2011).…”

“…Finally, the root prior was set at 160 Ma (sd AE 5 Myr), corresponding to an initial divergence separating Asian and Australian polystomes from all other neobatrachian polystomes (Badets et al, 2011), hypothetically corresponding to a separation of the western and eastern components of Gondwanaland. Divergence time estimates (see Verneau et al, 2009b) are reported for two nodes that are relevant for understanding the origin of the new Malagasy genus, i.e. Madapolystoma (see Du Preez et al, 2010).…”

Parapedocotyle prolatili gen. n. et sp. n., a representative of a new subfamily of the Diclidophoridae (Monogenea), a gill parasite of Prolatilus jugularis (Teleostei: Pinguipedidae) from Chile

“…Amplification for each molecular marker was done according to the Oliva et al: Parapedocotylinae, new subfamily of Diclidophoridae protocols described by Chisholm et al (2001), Hall et al (1999) and Verneau et al (2009) for the 28S rDNA, 18S rDNA gene and cox1 gene, respectively. Double-stranded PCR products were cleaned using an E.Z.N.A.…”

“…The 18S rRNA gene was amplified with forward primer Sb3a (5'-GGAGGGCAAGTCT-GGTGC-3') and the reverse primer A27a (5'-CCATACAAAT-GCCCCCGTCTG-3') following the protocol described by Hall et al (1999). The cox1 gene was amplified with forward L-CO1 (5'-TTTTTTGGGCATCCTGAGGTTTAT-3') and the reverse primer H-CO1 (5'-TAAAGAAAGAACATAATGAAAATG-3') (Verneau et al 2009). …”

Exploring non-invasive sampling of parasites by metabarcoding gastrointestinal nematodes in Madagascar frog species

“…Thus it is necessary to survey parasite assemblages in environments with different levels of anthropogenic influence . Indeed, there have been recent parasitological surveys on Malagasy frogs on monogeneans (Verneau et al, 2009;Du Preez et al, 2010;Raharivololoniaina et al, 2011;Berthier et al, 2014), mites (Wohltmann et al, 2007) and protists (Delvinquier et al, 1998), while nematodes were surveyed broadly in 1950s and 1960s (Chabaud Brygoo 1957, 1958Chabaud et al, 1961, although see recent information in Kuzmin et al, 2013).…”