Redescription and molecular analysis of Neoechinorhynchus (Neoechinorhynchus) johnii Yamaguti, 1939 (Acanthocephala, Neoechinorhynchidae) from the Pacific Ocean off Vietnam

Abstract

Neoechinorhynchus (Neoechinorhynchus) johnii Yamaguti, 1939 is redescribed from Eleutheronema tetradactylum (Polynemidae), Johnius carouna (Sciaenidae), Johnius sp., and Otolithes ruber (Sciaenidae) along the north and south coasts of Vietnam. Our description completes missing and inadequate information in the original descriptions and line drawings from Johnius goma in Japan and from Pseudosciaena diacanthus in the Indian Ocean. We add new information documented by scanning electron microscopy (SEM) and photomicroscopy, and explore the wide morphological diversity attributed to host species. The redescription includes: worms cylindrical with round proboscis with prominent apical organ, and large anterior hooks distant from small middle and posterior hooks; neck longer than the proboscis, nucleated lemnisci subequal, and receptacle with large basal triangulate cephalic ganglion and attached para-receptacle structure (PRS); male reproductive system in posterior half of trunk; adult females with introvert genital vestibule; and eggs spherical or rectangular. Gallium cuts and X-ray scans of hooks show high concentrations of sulfur on edge layer aiding in forming hardened calcium phosphate apatite of that layer with calcium and phosphorus in higher concentration in central part of hook. Molecular results consistently yielded a strongly supported distinct clade for the Neoechinorhynchus species from Vietnam for both 18S gene and the ITS1-5.8S-ITS2 region of ribosomal RNA. Phylogenetic analysis demonstrated that N. johnii occupies a separate position in the trees, probably indicating an Asian origin of this species.

A comparative assessment of the morphology ofProfilicollis altmani(Acanthocephala, Polymorphidae) from crustaceans and shore birds in Peru, with special notes on hook elemental analysis (EDXA), SEM imaging, histopathology, and molecular profile

“…5), rooted with prominent anterior manubria (Figs. [17][18][19][20]. Hook tips with high level of sulfur and low levels of phosphorous and calcium and midhook showing opposite trend.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and on 20 cystacanths (13 males and 7 females) measured and studied with microscopic images (Figs. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] from whole mounts obtained from E. analoga in Peru is provided below.…”

“…Fifth hook abruptly shorter but thickest, 6th hook, smallest; hooks gradually increasing in size posteriorly to maximum basally (Figs. [17][18][19][20]. Complete measurements of hooks in 1 longitudinal row in Table 2.…”

Redescription and molecular analysis ofPallisentis(Pallisentis)nandaiSarkar, 1953 (Acanthocephala: Quadrigyridae) in India

“…Molecular methods are an important tool for morphological identification, diversity and taxonomic relationships among acanthocephalan species (García-Varela et al ., 2017, 2019; Li et al ., 2018; Amin et al ., 2019a, b, c; Lisitsyna et al ., 2019; Menasria et al ., 2019; Sharifdini et al ., 2020). The phylogenetic relationships and systematic position of Pallisentis are poorly explored compared to other genera.…”

“…The presence of the PRS in eoacanthocephalan species with a weak single proboscis receptacle wall was first demonstrated in Neoechinorhynchus (N.) qatarensis Amin, Saoud, Alkuwari, 2002by Amin et al (2002. It had since been reported in other eoacanthocephalan species of Neoechinorhynchus Stiles & Hassall, 1905 and Acanthogyrus (Acanthosentis) Verma & Datta, 1929 by Amin (2005) and Amin et al (2011aAmin et al ( , 2019a.…”