Characterization of Clinostomum (Digenea: Clinostomidae) spp. in India

Abstract

Platyhelminths belonging to the family Clinostomidae (Digenea) have a worldwide distribution and are known to infect piscivorous birds through their intermediate hosts, usually fish species. In the present study, clinostome metacercariae were collected from fish hosts, including Channa punctata (Bloch 1793) (n = 25) and Trichogaster fasciata Bloch and Schneider 1801 (n = 25), from a freshwater system in India. The experimental infection of cattle egrets, Ardea (Bubulcus) ibis Linnaeus 1758, with some of the live metacercariae found in the present study was successful. Live adult parasites were obtained from the buccal cavity of the birds. Both metacercaria and adult specimens were subjected to molecular studies to obtain the sequences of 28S, ITS1, and ITS2 (nuclear rDNA) regions. The parasites were found to belong to three species, Clinostomum giganticum Agarwal 1959; C. piscidium Southwell and Prashad 1918; and Euclinostomum heterostomum (Rudolphi 1809). Phylogenetic analyses of the sequences obtained from the adults and metacercariae established a link between the metacercariae in the fish hosts and adults in the avian host, which is essential to elucidate their partial life cycle and specify morphological characteristics in the metacercarial stage.

Morphological and molecular identification of Euclinostomum heterostomum in the spotted snakehead (Channa punctata) in Narayanganj, Bangladesh

“…Several combined morphometric and molecular approaches were used to identify metacercariae of E. heterostomum in cichlids (Caffara et al, 2016). The observed sucker ratios align with various studies that report the oral sucker to ventral sucker size ratio ranging from one-third to one-half (Choudhary et al, 2022). Clinostomum can be distinguished on the basis of size, tegumental spines, and various aspects of the genital complex from named and unnamed species in the same region (Caffara et al, 2020).…”

Genetic characterization and phylogenetic relationships of Phyllodistomum parasites in Indian subcontinent: insights from freshwater fish and shrimp hosts

“…Sequence data have proven to be invaluable in elucidating the life cycles of digeneans, which typically exhibit an indirect life cycle. The use of genetic information, such as DNA sequencing of specific regions like 28S rRNA, ITS1, and CoxI, has provided crucial insights into the complex life cycles of these parasitic flatworms (Huston et al 2018 ; Rochat et al 2020 ; Shamsi et al 2021a ; Shamsi et al 2021b ; Shamsi et al 2023 , Barton et al 2022 ; Choudhary et al 2022 ).…”

Molecular characterization of Clinostomum spp. infecting cultured Snakeskin gourami (Trichopodus pectoralis) in Thailand

“…Clinostomidae parasites are cosmopolitan, possibly zoonotic flukes that have been little researched in Thailand using molecular taxonomic methods. Mainly, morphological distinctions across the several phases of parasite growth have made their identification more complex (Choudhary et al, 2022). Thus, to ensure more accuracy in identifying Clinostomum species, morphological identification has been advised to be paired with DNA evidence (Briosio-Aguilar et al, 2019); this is what the current research has done.…”

“…and Clinostomum piscidium, which are often indistinguishable. Body size and shape, sucker ratio, and, most noticeably, genital complex structure are only some morphological changes that occur throughout the metacercariae's metamorphosis into an adult (Choudhary et al, 2022). Notably, most of the cuticular spines might be destroyed during the staining and experimental process and not be seen on a permanent slide (Caffara et al, 2014).…”