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

Acanthocephalans from freshwater fishes in northeast Thailand with the description of a new species of the subgenus Acanthosentis Verma & Dutta, 1929 (Acanthocephala, Quadrigyridae)

During an ichthyoparasitological survey in northeast Thailand in 2015, four species of acanthocephalans were found in four species of freshwater fishes. Adult stages of Pallisentisrexus Wongkham & Whitfield, 1999 and Raosentis sp. (Eoacanthocephala, Quadrigyridae) were collected from Channastriata (Anabantiformes, Channidae) and Mystusmysticetus (Siluriformes, Bagridae), respectively, and cystacanths of Arhythmorhynchus sp. (Palaeacanthocephala, Polymorphidae) were found on the visceral organs of M.albolineatus (Siluriformes, Bagridae). Adult acanthocephalans of the subgenus Acanthosentis Verma & Dutta, 1929 isolated from Barbonymusschwanenfeldii (Cypriniformes, Cyprinidae) were morphologically distinct from all described species of the subgenus in the arrangement of rings of tegumental spines in two fields with a more or less pronounced distance between them, and by the presence of a dome-shaped process with a ring of small spines at the base at the posterior end in females. Molecular data were generated for three species and phylogenetic analysis based on the 18S rDNA clearly supported the generic identification of Acanthogyrus (Acanthosentis) barbonymisp. nov. and P.rexus. While the phylogenetic position of the former species within the genus could not be clarified, the latter species formed a well-supported sister lineage in a clade with isolates of four congeneric species. Acanthogyrus (Acanthosentis) barbonymisp. nov. is formally described, the first genetic data for P.rexus are generated, a species of the genus Raosentis Datta, 1947 is reported for the first time outside the Indian subcontinent, and a key to the species of the latter genus is presented.

Morphological and Molecular Characterization of Two New and Two Already Known Species of the Genus Pallisentis (Acanthocephala: Quadrigyridae) from India with an Update in Key to the Species

To date, 31 species assigned to the genus Pallisentis Van cleave, 1928 have been reported from India. The present study includes morphological and molecular descriptions of two new species of Pallisentis Van Cleave, 1928, namely P. himachalensis and P. longus from the fresh water fishes Channa punctata (Bloch, 1793) and C. marulius (Hamilton, 1822), respectively, procured from Himachal Pradesh and Chandigarh, India. Of total 35 fishes, 17 were found infected with acanthocephalan parasites. The prevalence of infection was 42.85 and 52.38% for C. punctata and C. marulius, respectively. The morphological characters of P. himachalensis n. sp. include proboscis with 4 circles of hooks with 810 hooks per circle, which gradually decline in size. The trunk in male comprises 1516 circles of collar spines and 2737 circles of trunk spines ending above the anterior testis with syncytial cement gland having 2629 nuclei. The trunk in female comprises of 1418 circles of collar spines and 5573 circles of trunk spines present till the anterior end of reproductive system with additional 34 circles at the posterior end. P. longus n. sp. is the longest species reported in the genus and the length of female reach up to 44 mm. The proboscis comprises 4 circles of proboscis hooks with 910 hooks per circle. In males 1316 circles of the collar spines and 2731 circles of trunk spines are present with syncytial cement gland containing 2025 nuclei. The females are much longer with 1516 circles of collar spines and 6469 circles of trunk spines present till the posterior end. The study also reports two already described species: P. gomtii Gupta and Verma, 1980 from C. punctata and P. nandai Sarkar, 1953 from C. marulius. Total 12 sequences for 4 species have been generated based on 18S, 28S and ITS15.8SITS2 molecular markers. The 18S and ITS15.8SITS2 Bayesian inference trees generated in the present study showed distinct identities of all 4 species. Moreover, the Bayesian inference tree generated in the present study based on 18S showed the clustering of Pallisentis species in three different clades compared to the previous studies in which only two clades within the genus were reported. The molecular analysis showed the monophyletic origin of the genus Pallisentis and does not support subgeneric classification within the genus.