Morphological Characteristics and Phylogenetic Trends of Trematode Cercariae in Freshwater Snails from Nakhon Nayok Province, Thailand.
The prevalence of cercarial infection in freshwater snails and their evolutionary trends were studied in Nakhon Nayok province, Thailand. A total of 2,869 individual snails were examined for parasitic infections. The results showed that 12 snail species were found to host larval stages of trematodes with an overall prevalence of 4.7%. The infected specimens included 7 types at the cercarial stage; cercariae, megalurous cercariae, echinostome cercariae, furcocercous cercariae, parapleurolophocercous cercariae, virgulate cercariae, and xiphidiocercariae. Regarding molecular identification, ITS2 sequence data of each larval trematode were analyzed, and a dendrogram was constructed using the neighbor-joining method with 10,000 replicates. The dendrogram was separated into 6 clades (order/family), including Echinostomatida/Echinostomatidae, Echinostomatida/Philophthalmidae, Opisthorchiida/Heterophyidae, Plagiorchiida/Prosthogonimidae, Plagiorchiida/Lecithodendriidae, and Strigeatida/Cyathocotylidae. These findings were used to confirm morphological characteristics and evolutionary trends of each type of cercariae discovered in Nakhon Nayok province. Furthermore, this investigation confirmed that the ITS2 data of cercariae could be used to study on phylogenetic relationships or to determine classification of this species at order and/or family level when possible.
['Chontananarth|Thapana|T|', 'Tejangkura|Thanawan|T|', 'Wetchasart|Napat|N|', 'Chimburut|Cherdchay|C|']
D000818:Animals D016000:Cluster Analysis D018509:DNA, Helminth D021903:DNA, Ribosomal Spacer D005618:Fresh Water D008853:Microscopy D010802:Phylogeny D015995:Prevalence D017422:Sequence Analysis, DNA D012908:Snails D013785:Thailand D014200:Trematoda
trematode cercaria snail Nakhon Nayok province Thailand prevalence ITS2 phylogenetic relationship