Phylogenetic relationships of two species of Haematoloechus (Trematoda: Haematoloechidae) infecting Euphlyctis spp. from the biodiversity hotspot, Western Ghats, India.

During a parasitological survey in the biodiversity hotspot, two species of the digenetic trematode, Haematoloechus from the lungs of Indian skipper frog Euphlyctis cyanophlyctis and the Indian green frog, E. hexadactylus inhabiting the biodiversity hotspot, Western Ghats, India, were found and described using morphological and molecular tools. Morphological examinations indicated that the two species are Haematoloechus almorai Pande, 1937 and H. (H.) variegatus capyristes (Klein, 1905; Ingles, 1932) Odening, 1958 as previously described in the original manuscripts but with some morphological differences. The ITS region (ITS1, 5.8S and ITS2) and 28S gene of ribosomal DNA sequences were performed for phylogenetic studies showed that the sequences of these species did not match with any of the previously reported sequences on GenBank database. Phylogenetic analysis placed H. almorai and H. (H.) variegatus capyristes in a well-supported clade under the genus Haematoloechus. This is the first molecular study of present Haematoloechus species from the Western Ghats, India and discussed their phylogenetic position.

Further contribution to the life history of Centrocestus formosanus (Nishigori, 1924) Price, 1932 (Trematoda: Heterophyidae) with special reference to a new first intermediate host from the South Western Ghats, India.

Centrocestus formosanus is a zoonotic small invasive heterophyid fluke with worldwide distribution. Its three-host life cycle requires a thiarid snail as first intermediate host, fishes as second intermediate hosts and piscivorous birds and mammals as definitive hosts for completion. As far as is known, the only first intermediate host being utilized, globally, by this parasite is the snail, Melanoides tuberculata. In the present study, life cycle stages of C. formosanus were recovered naturally and successfully tested in the laboratory. Study also adds a new host to its life cycle, the snail Bithynia (Digoniostoma) pulchella, as the first intermediate host with natural infection. Parasitological descriptors (prevalence, mean intensity and mean abundance) of infection were measured for each host. Being an invasive parasite, addition of a new host to C. formosanus life cycle has notable ecological and evolutionary significance.

Phylogenetic position of Tremiorchis ranarum Mehra and Negi, 1926 (Trematoda: Plagiorchiidae) with remark on this monotypic genus.

Tremiorchis is a monotypic genus of digenetic trematode (Plagiorchiidae: Plagiorchiinae), infecting the frogs Rana tigrina (Hoplobatrachus tigerinus) and R. cyanophlyctis (Euphlyctis cyanophlyctis). Metacercaria use to infect Rana tigrina (Hoplobatrachus tigerinus) and R. cyanophlyctis (Euphlyctis cyanophlyctis) as intermediate hosts, while the cercaria stage found from apple snail, Pila virens. Adults of T. ranarum harbor mature frogs of H. tigerinus and E. cyanophlyctis. Besides the frequent infection of Tremiorchis, no DNA sequence data are currently available for this monotypic genus. The present communication, deals with the sequence data for nuclear ribosomal genes, 18S, small internal transcribed spacers (ITS1-5.8S-ITS2) and 28S to molecularly characterize T. ranarum. Besides this, phylogenetic relationship among the members of the Plagiorchiida is also discussed in detail. An attempt has also been made to provide detailed molecular affinities of T. ranarum with other trematode genera.

Spatio-temporal and host-dependent variations in prevalence and intensity of heterophyid (Digenea: Heterophyidae) metacercariae infection in brackishwater and freshwater fishes: a comparative study.

Studies on distribution of parasites are important to reveal the ecology of host-parasites interactions. The objective of the study was to compare the variations in heterophyid encysted metacercariae (EMC) infection in freshwater and brackishwater fish hosts and variation in parasitological descriptors of metacercariae infection during different seasons. The status of infection with heterophyid EMCs in the second intermediate host fishes from brackishand freshwater resources was investigated. Seasonal changes in the occurrence of EMCs in different fish hosts were monitored in a longitudinal field survey lasting 12 months from June 2018 to May 2019. Distribution of heterophyid EMCs was found varied in freshwater and brackishwater fishes with higher prevalence in brackishwater fish. There was a distinct seasonal trend in the prevalence of infection for all heterophyid EMCs in the brackishwater fish examined with high burden during summer. Thus variations in parasitic infection among hosts underpin the importance of parasites as an evolutionary or ecological force.