title: Ancient divergence of Paragonimus westermani in Sri Lanka.
abstract: Adult flukes of Paragonimus species were obtained from lungs of experimental animals infected with metacercariae found in field-collected freshwater crabs in Sri Lanka. Morphological studies of adult worms under a scanning electron microscope as well as a ordinary microscope were performed in the present study. All of morphological features observed clearly indicated that this species is P. westermani. On the other hand, the shapes of metacercariae were found to be mainly oval, but semioval and spherical ones also coexisted. In spite of the variety of their morphology of the metacercariae, there is no correlation between their shapes of metacercariae and the deoxyribonucleic acid (DNA) sequences. Molecular phylogenetic analyses using two DNA regions (partial mitochondrial cytochrome c oxidase subunit 1 and second internal transcribed spacer of the nuclear ribosomal gene repeat) placed the adult flukes of P. westermani from Sri Lanka basal in a tree including all specimens of P. westermani from various areas in Asia and P. siamensis from Thailand. The present study showed that P. westermani from Sri Lanka is an ancestral form.
authors.affiliation: Department of Environmental Health Science, Kochi Medical School, Oko, Nankoku city, Kochi 783-8505, Japan.
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Iwagami
authors.forename: R P V J
authors.initials: RP
authors.lastname: Rajapakse
authors.forename: Wijithe
authors.initials: W
authors.lastname: Paranagama
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Okada
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kano
authors.forename: Takeshi
authors.initials: T
authors.lastname: Agatsuma
mesh_terms: D000818:Animals; D001483:Base Sequence; D003386:Brachyura / Q000469:parasitology*; D018509:DNA, Helminth / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D003576:Electron Transport Complex IV / Q000235:genetics; D019143:Evolution, Molecular; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D048492:Paragonimus westermani / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013188:Sri Lanka
chemical_list: D018509:DNA, Helminth; D021903:DNA, Ribosomal Spacer; D003576:Electron Transport Complex IV