A new genus and species of turtle blood fluke (Digenea: Schistosomatoidea) from the Mekong snail-eating turtle, Malayemys subtrijuga (Schlegel & Müller) (Testudines: Geoemydidae) in Vietnam, with a reassessment of related Asiatic turtle blood flukes and molecular phylogeny

Abstract

Platt sinuosus Roberts & Bullard n. g., n. sp. (type-species) infects the kidney and mesenteric blood vessels of Mekong snail-eating turtles, Malayemys subtrijuga (Schlegel & Müller), in the Mekong River Basin. Species of Platt Roberts & Bullard n. g. are unique by the combination of having a papillate ventral sucker, vasa efferentia that are dorsal to the gonads, a massive cirrus-sac that is directed anteriad or laterad, and a vitellarium that surrounds the intestinal caeca. The new species resembles Platt ocadiae (Takeuti, 1942) Roberts & Bullard n. comb. but differs from it by having an external seminal vesicle that overlaps with or is immediately posterior to the level of the ventral sucker. Seven species previously of Hapalorhynchus Stunkard, 1922 are reassigned herein to Platt: P. odhnerensis (Mehra, 1933) Roberts & Bullard n. comb.; P. yoshidai (Ozaki, 1939) Roberts & Bullard n. comb.; P. ocadiae; P. oschmarini (Belous, 1963) Roberts & Bullard n. comb.; P. sutlejensis (Mehrotra, 1973) Roberts & Bullard n. comb.; P. synderi (Platt & Sharma, 2012) Roberts & Bullard n. comb.; and P. tkachi (Platt & Sharma, 2012) Roberts & Bullard n. comb. A dichotomous key to Platt spp. is provided. Hapalorhynchus sheilae (Mehrotra, 1973) Bourgat, 1990 and Hapalorhynchus mica (Oshmarin, 1971) Bourgat, 1990 are considered as species inquirendae, and Hapalorhynchus indicus (Thapar, 1933) Price, 1934 and Hapalorhynchus macrotesticularis (Rohde, Lee, & Lim, 1968) Brooks & Sullivan, 1981 are considered as species incertae sedis. Phylogenetic analysis of the large subunit rDNA (28S) showed P. sinuosus and P. snyderi to be sister taxa distinct from a monophyletic Hapalorhynchus and Coeuritrema platti Roberts & Bullard, 2016.

Neotropical Turtle Blood Flukes: Two New Genera and Species from the Amazon River Basin with a Key to Genera and Comments on a Marine-Derived Parasite Lineage in South America

“…Because some TBF genera include species that need re-description or re-assignment to other genera, we base our comparisons on the type species of each genus principally. Previous work from Roberts and Bullard have treated revisions of several TBF genera (Roberts et al, 2016a(Roberts et al, , 2016b(Roberts et al, , 2016c(Roberts et al, , 2018a(Roberts et al, , 2018b(Roberts et al, , 2019, but, where appropriate, we indicate exceptions to generic diagnoses that suggest needed revisionary work.…”

“…All of these genera comprise species that infect freshwater turtles only. Platt differs from Hapalorhynchus by having a papillate ventral sucker and a massive cirrus sac that is directed anteriad or laterad, whereas Hapalorhynchus has an apapillate ventral sucker and a diminutive cirrus sac, if present (Roberts et al, 2018a). Platt differs from Coeuritrema by lacking ventrolateral tegumental mammillae and by having a diminutive metraterm that is not readily distinguished from the distal portion of the uterus.…”

“…During July 2016, the viscera of 5 matamatas (C. fimbriata) from the Bele´n Market (3845 0 32.08 00 S, 73814 0 53.15 00 W), Iquitos, Peru (Amazon River), were examined opportunistically for blood fluke infections following previously published procedures (Roberts et al, 2016a(Roberts et al, , 2016b(Roberts et al, , 2016c(Roberts et al, , 2018a(Roberts et al, , 2018b(Roberts et al, , 2019 observed microscopically prior to fixation, fixed in 5À10% neutral buffered formalin (nbf) for morphology, or preserved in 95% non-denatured ethanol (EtOH) for DNA extraction. The ovoid TBF specimens with a relatively thick tegument (i.e., specimens of the first new species described below) were routinely heat-killed on glass slides using a butane hand lighter under little or no coverslip pressure.…”

“…This result is interesting because it demonstrates that the marine TBFs are both paraphyletic but also rather distantly related (i.e., species of Neospirorchis have a freshwater turtle TBF ancestor). Roberts et al [2018a]). These genera have the anatomical sequence (anterior to posterior) of a ventral sucker, external seminal vesicle, cirrus sac (lateral to the metraterm), anterior testis, ovary, transverse vitelline duct (intertesticular), and posterior testis (Fig.…”

“…Coeuritrema has ventrolateral mammillae and a massive metraterm. Platt can be readily differentiated from Cardiotrema by having a large ventral sucker (one-fourth to one-half body width) that is immediately posterior to the cecal bifurcation, whereas Cardiotrema has a rudimentary ventral sucker far posterior to the cecal bifurcation (Roberts et al, 2018a).…”