Abstract
BackgroundPolystomatid flatworms in chelonians are divided into three genera, i.e. Polystomoides Ward, 1917, Polystomoidella Price, 1939 and Neopolystoma Price, 1939, according to the number of haptoral hooks. Among the about 55 polystome species that are known to date from the 327 modern living chelonians, only four species of Polystomoides are currently recognised within the 45 South American freshwater turtles.MethodsDuring 2012, several sites in the vicinity of the cities Cayenne and Kaw in French Guiana were investigated for freshwater turtles. Turtles were collected at six sites and the presence of polystomatid flatworms was assessed from the presence of polystome eggs released by infected specimens.ResultsAmong the three turtle species that were collected, no polystomes were found in the gibba turtle Mesoclemmys gibba (Schweigger, 1812). The spot-legged turtle Rhinoclemmys punctularia (Daudin, 1801) was infected with two species of Neopolystoma Price, 1939, one in the conjunctival sacs and the other in the urinary bladder, while the scorpion mud turtle Kinosternon scorpioides (Linnaeus, 1766) was found to be infected with a single Neopolystoma species in the conjunctival sacs. These parasites could be distinguished from known species of Neopolystoma by a combination of morphological characteristics including body size, number and length of genital spines, shape and size of the testis. They were also differentiated at the molecular level using the cox1 gene marker. Based on morphological and genetic evidences, three new species are described herein, namely Neopolystoma cayensis n. sp. and Neopolystoma guianensis n. sp. from the bladder and the conjunctival sacs of R. punctularia, respectively, and Neopolystoma scorpioides n. sp. from the conjunctival sacs of K. scorpioides. However the monophyly of Polystomoides and Neopolystoma is still questioned regarding their phylogeny based on a dataset comprising four concatenated genes, namely, 18S, 28S and 12S rRNA genes and cox1.ConclusionsIn addition to these being the first chelonian polystomes to be reported and described from French Guiana, they represent the first polystomes from the hosts K. scorpioides and R. punctularia and the first representatives of Neopolystoma from South America. Chelonian polystomes now require an in-depth morphological study to reconcile the taxonomy of the genera with species evolution.
Highlights
Polystomatid flatworms in chelonians are divided into three genera, i.e. Polystomoides Ward, 1917, Polystomoidella Price, 1939 and Neopolystoma Price, 1939, according to the number of haptoral hooks
Among the 68 turtles that were collected, two chelonian species were found to be infected with polystomes, i.e. R. punctularia and K. scorpioides, whereas M. gibba was uninfected
Based on the absence of hamuli, all parasites found in the bladder and in the conjunctival sacs of their host could be considered at that stage as belonging to Neopolystoma
Summary
Polystomatid flatworms in chelonians are divided into three genera, i.e. Polystomoides Ward, 1917, Polystomoidella Price, 1939 and Neopolystoma Price, 1939, according to the number of haptoral hooks. Besides its exceptional richness in freshwater fishes [3], this ecoregion exhibits a great diversity of freshwater turtles with ten species known to date [4]. These include the matamata turtle Chelus fimbriata (Schneider, 1783), the scorpion mud turtle Kinosternon scorpioides (Linnaeus, 1766), the gibba turtle Mesoclemmys gibba (Schweigger, 1812), the Guyanan toad-headed turtle Mesoclemmys nasuta (Schweigger, 1812), the big-headed sideneck turtle Peltocephalus dumerilianus (Schweigger, 1812), the Guianan shield side-necked turtle Phrynops tuberosus (Peters, 1870), the twist-necked turtle Platemys platycephala (Schneider, 1792), the giant South American river turtle Podocnemis expansa (Schweigger, 1812), the yellow-spotted river turtle Podocnemis unifilis Troschel, 1848 and the spot-legged turtle Rhinoclemmys punctularia (Daudin, 1801). They appear to be less specific following host releases, which has been demonstrated in confined and natural environments after translocation of American freshwater turtles, especially red-eared sliders Trachemys scripta elegans (Wied, 1939) [23,24,25]
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