Four New Species of the Genus Pallisentis (Quadrigyridae, Van Cleave, 1920) from Freshwater Fish in Uttar Pradesh, India

Morphological and molecular description of Pallisentis roparensis n. sp. (Acanthocephala: Quadrigyridae) infecting the freshwater cat fish Wallago attu from Ropar Wetland, Punjab, India

The study describes a new species of Pallisentis Van Cleave, 1928 infecting the freshwater cat fish Wallago attu Bloch and Schneider, 1801 from Ropar wetland, Punjab, India. The morphological characters of Pallisentis roparensis include proboscis with 4 circles of 10 hooks each gradually declining in size, first circle of hooks <100 μm in length, 15–16 circles of Y-shaped collar spines and conical trunk spines present up to the posterior end in the females and the anterior region of cement gland in males. Saefftigen's pouch is present and cement gland nuclei are 22–25 in males. The sequences generated for 18S, 28S and ITS1-5.8S-ITS2 molecular markers of the newly described species are nested well among the other comparable sequences from the GenBank. The phylogenetic analyses show the monophyly of the genus Pallisentis but point towards the paraphyletic relationship among the three subgenera. The histopathology of fish intestine indicates that the parasite stimulates the inflammatory immune response causing serious injury to the mucosa and dilation of the lymphatic vessels of small intestine.

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Description of Pallisentis roparensis n. sp. from a freshwater cat fish Wallago attu from Ropar wetland, Punjab, India.

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Phylogenetic analyses show well nested sequences of new species within the genus and monophyly of the genus Pallisentis.

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Molecular data does not show any trend towards the sub-generic classification based on morphology within the genus.

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Histopathological study of infected host intestine shows mechanical damage and inflammatory immune response..

Phylogenetic analysis of Pallisentis nagpurensis (Acanthocephala: Quadrigyridae) infecting snakehead murrel Channa striata in Himachal Pradesh, India

Till date 34 species of Pallisentis have been validated with almost negligible studies on its molecular phylogeny. The discovered species of the genus Pallisentis are confined only to the Asian continent. Many different species of Acanthocephala infecting commercially important freshwater as well as the marine fishes have been recorded from India mainly on the basis of morphology. The original record of morphological characteristics of Pallisentis nagpurensis (Bhalerao 1931) Baylis, 1933 can be traced back to the Bhalerao, 1931 from Channa striata (Ophiocephalus striatus) from the state of Uttar Pradesh, India without the separate documentation of male and female characteristics. Same species has also been reported to infect Channa striata from different parts of India as well as from the Indonesia and Ceylon (Baylis, 1933 and Fernando and Furtado, 1963). The present study compiles the morphological characteristics of male and female P. nagpurensis along with the comparison with similar species from same geographical region. This study also reports the first record of 18S, 28S rRNA and ITS1-5.8S-ITS2 gene sequences of P. nagpurensis generated for analyzing the phylogeny within this taxonomic group. P. nagpurensis together with the other species of Pallisentis reported from India distinctly formed a sub-clade separating it from the other members of same genus.

Redescription and molecular analysis of Pallisentis (Pallisentis) nandai Sarkar, 1953 (Acanthocephala: Quadrigyridae) in India

Pallisentis (Pallisentis) nandai Sarkar, 1953 is a freshwater fish parasite restricted to the Indian subcontinent in the Ganga River and its tributaries. It was described from the leaffish, Nandus nandus (Hamilton) from the Ganga River delta at Calcutta. We recovered variant specimens from the same host species from the Ganga near its headwaters at Bijnor about 1500 km away. Our specimens were clearly identifiable as P. nandai but varied considerably from those in the original description, especially in the size of proboscis hooks, receptacle and lemnisci. The original description was incomplete (missing line drawings of female trunk and reproductive system, male trunk, complete proboscis, hooks and hook roots) and inaccurate (proboscis, hooks, receptacle wall), and some measurements were lumped together for both sexes. We provide a complete description and include new morphological information including the first description of para-receptacle structure in the genus Pallisentis Van Cleave, 1928, scanning electron microscopy and microscope images, molecular analysis, and energy dispersive X-ray analysis (EDXA) of hooks and spines of our specimens for the first time. Additional details of proboscis hook roots, trunk spines, micropores and micropore distribution are described. The unique metal composition of hooks (EDXA) demonstrated a considerably high but variable level of sulphur and negligible level of calcium in collar and trunk spines and hook tips, but a higher level of sulphur and calcium at the hook basal arch than at the hook tip and edge. A comparison with the EDXA pattern of another species of Pallisentis, P. İndica Mital & Lal, 1976, were considerably different. The phylogenetic position of P. nandai within Eoacanthocephala was generated to assess the molecular characterization based on 18S and ITS1-5.8S-ITS2 ribosomal DNA sequences. Maximum likelihood and Bayesian inference analyses placed P. nandai in a clade with other Pallisentis species under the family Quadrigyridae. This is the first report based on molecular evidence for P. nandai.