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

Abstract

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 8–10 hooks per circle, which gradually decline in size. The trunk in male comprises 15–16 circles of collar spines and 27–37 circles of trunk spines ending above the anterior testis with syncytial cement gland having 26–29 nuclei. The trunk in female comprises of 14–18 circles of collar spines and 55–73 circles of trunk spines present till the anterior end of reproductive system with additional 3–4 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 9–10 hooks per circle. In males 13–16 circles of the collar spines and 27–31 circles of trunk spines are present with syncytial cement gland containing 20–25 nuclei. The females are much longer with 15–16 circles of collar spines and 64–69 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 ITS1–5.8S–ITS2 molecular markers. The 18S and ITS1–5.8S–ITS2 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.