| Nattawadee Nantarat | 3 Articles |
This study aimed to describe the morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae isolated in Thailand. Adult flukes were isolated from the Chinese pipistrelle bat (Hypsugo sp.), and cercariae were detected in the viviparid snail (Filopaludina martensi martensi) from Chiang Mai province. The morphological characteristics were observed and described using conventional methods, and the molecular characteristics with internal transcribed spacer 2 (ITS2) and 28S rDNA gene sequences. The adult flukes were fusiform, 0.84–0.98 mm in length, and 0.37–0.49 mm in width, and were distinguishable from other species by the presence of longitudinal uterine coils. The cercariae were nonvirgulate xiphidiocercariae, with the oral sucker bigger than the acetabulum, the tail without fin fold, a body size of 117.5–138.3 × 48.3–52.2 µm, and a tail size of 100.7–103.7 × 15.0–18.9 µm. Molecular studies revealed that the adults and cercariae shared 99.3% (ITS2) and 99.6% (28S rDNA) homology with each other. They were phylogenetically close to P. longiforme with an identity of 94.5% for ITS2 and 98.7% for 28S rDNA. This study provides new information on the natural definitive host and first intermediate host of P. longiforme in Thailand. The discovery of its cercarial stage in Filopaludina snails highlights the importance of monitoring the associated second intermediate host and prevention and control of this potentially zoonotic trematode.
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We tried a series of morphological and molecular approaches to identify a new species of Stellantchasmus (Digenea: Heterophyidae) originating from the wrestling half-beaked fish, Dermogenys pusillus of Thailand. Adult worm samples of the new species were recovered from hamsters experimentally infected with the metacercariae from D. pusillus in Thailand. Two isolates (Thai and Korean) of Stellantchasmus falcatus were used as comparative control groups. Worm samples of 3 Stellantchasmus groups were morphologically observed and molecularly analyzed with the mitochondrial cytochrome c oxidase 1 gene. The morphological characteristics of S. dermogenysi n. sp. are similar to S. falcatus originating from brackish water fish, but minor difference was noted including the absence of the prepharynx, position of the ovary near the ceca end, smaller body size, and shorter esophageal length. A phylogenetic tree derived from neighborjoining and maximum-likelihood methods suggests that S. dermogenysi n. sp. is separated from S. falcatus supported by high bootstrap values. The relative divergences persist between these host-specific trematodes, which we suggest should be recognized as 2 distinct species. Comparisons of S. dermogenysi n. sp. with S. falcatus isolated from mullets in Thailand and Korea indicate a genetic divergence of mitochondrial DNA of 19.4% and 21.7%, respectively. By the present study, a new species, Stellantchasmus dermogenysi n. sp. (Digenea: Heterophyidae), is proposed in Thailand based on molecular evidences, in addition to minor morphological differences between S. falcatus and the new species.
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This study aimed to investigate the morphology and reconstruct the phylogenetic relationships of Centrocestus formosanus originating from 5 species of freshwater fish, i.e., Esomus metallicus, Puntius brevis, Anabas testudineus, Parambassis siamensis, and Carassius auratus, in Chiang Mai province, Thailand. Sequence-related amplified polymorphism (SRAP) and phylogeny based on internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (CO1) were performed. The results showed similar morphologies of adult C. formosanus from day 5 after infection in chicks. C. formosanus originated from 4 species of freshwater fish had the same number of circumoral spines on the oral sucker, except for those from C. auratus which revealed 34 circumoral spines. The phylogenetic tree obtained from SRAP profile and the combination of ITS2 and CO1 sequence showed similar results that were correlated with the number of circumoral spines in adult worms. Genetic variability of C. formosanus also occurred in different species of freshwater fish hosts. However, more details of adult worm morphologies and more sensitive genetic markers are needed to confirm the species validity of C. formosanus with 34 circumoral spines originating from C. auratus in the future.
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