Cestode Parasites in Potamotrygon motoro (Natterer) (Chondrichthyes: Potamotrygonidae) from Southwestern Brazil, including Rhinebothroides mclennanae n. sp. (Tetraphyllidea: Phyllobothriidae), and a Revised Host-Parasite Checklist for Helminths Inhabiting Neotropical Freshwater Stingrays

Abstract

Specimens of 5 species of cestodes were collected in 6 specimens of the freshwater stingray species Potamotrygon motoro (Natterer), collected in the vicinity of Corumba, Mato Grosso do Sul, Brazil. Acanthobothrium regoi, Potamotrygonocestus orinocoensis, Rhinebothroides venezuelensis, and Rhinebothrium paratrygoni are reported from P. motoro and from southwestern Brazil for the first time. Rhinebothroides mclennanae n. sp. appears to be the sister species of Rhinebothroides glandularis, the only other member of the genus exhibiting darkly staining glandular cells lying free in the parenchyma surrounding the terminal genitalia. The new species resembles Rhinebothroides glandularis, Rhinebothroides freitasi, and Rhinebothroides scorzai by having poral ovarian arms that extend anteriorly beyond the posterior margin of the cirrus sac, coiled vaginae, and vitelline follicles not interrupted on the poral side in the vicinity of the genital pore. It differs from all 6 previously described members of the genus by possessing an average of 31 testes per proglottid, compared with an average of 45 for R. glandularis, 55 for R. freitasi and R. venezuelensis, 77 for Rhinebothroides circularisi and Rhinebothroides moralarai, and 80 for R. scorzai. An updated phylogenetic tree for Rhinebothroides is presented.

Ecology of endoparasites of the fluvial stingray Potamotrygon falkneri (Chondrichthyes: Potamotrygonidae) from the upper Paraná River floodplain, Brazil

“…The most prevalent species were Acanthobothrium regoi (12.76%) and Rhinebothrium paratrygoni (36.17%), cestodes that are not very specific, but parasitize only potamotrygonids (Brooks and Amato, 1992;Lacerda et al, 2008). Unfortunately, the majority of the studies with parasites of fluvial stingrays do not present information about parasitism levels, but we can say that the prevalence of Acanthobothrium regoi in P. falkneri in the present study is low when compared to other species of Acanthobothrium and other species of hosts, being closer to the values found in Argentina (Ivanov, 2005).…”

Rhinebothrium jaimei sp. n. (Eucestoda: Rhinebothriidea: Rhinebothriidae): a new species from Neotropical freshwater stingrays (Potamotrygonidae)

“…Despite earlier attempts to understand the evolution of the cestode parasites of potamotrygonids (Brooks et al 1981, Brooks 1992, 1995, Brooks and Amato 1992, Zamparo et al 1999, Marques 2000, there is still much to be learned about the lineages that comprise this interesting system. While the mechanisms that shaped the composition of the cestode fauna in Neotropical freshwater stingrays remain unknown, we are in the process of recognising the host and parasite lineages that comprise this system, in order to provide the taxonomic refinement to address more complex evolutionary questions.…”

Digenea, Nematoda, Cestoda, and Acanthocephala, parasites in Potamotrygonidae (Chondrichthyes) from the upper Paraná River floodplain, states of Paraná and Mato Grosso do Sul, Brazil

“…Also according to Szidat (1969) (Gibson 2002). According to Brooks and Amato (1992), there are records of Genarchella overstreeti (= Paravitellotrema overstreeti Brooks, Mayes & Thorson, 1981) in Potamotrygon magdalenae (Valenciennes, 1865) from Magdalena River (Colombia). Genarchella fragilis Lunaschi, 1990 was registered parasitizing Pimelodus ornatus Kner, 1858 (Siluriformes) in Paraná River by Fernandes and Kohn (2001).…”

“…The two formers are monospecific, while Potamotrygon has approximately 26 valid species (Carvalho et al 2003). Fifteen of these species have parasitological records, including the species of the present study, considering several regions: Salobra River (Paraguay River Basin, state of Mato Grosso, Brazil) (Rego 1979); vicinity of Corumbá (state of Mato Grosso do Sul, Brazil) (Brooks and Amato 1992); Amazonas River (Amazonas River Basin, Brazil) (Campbell et al 1999); Orinoco River delta (Orinoco River Basin, Venezuela) ; upper Madre de Dios River (Manu River Basin, Peru) (Reyda and Olson 2003).…”