Morphological updates and molecular description of Heterosentis holospinus Amin, Heckmann, & Ha, 2011 (Acanthocephala, Arhythmacanthidae) in the Pacific Ocean off Vietnam.

Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Arhythmacanthidae) was first described from the striped eel catfish, Plotosus lineatus (Plotosidae) in Halong Bay, Vietnam. New morphological information, scanning electron microscope images, molecular analysis, and Energy Dispersive X-ray analysis (EDXA) of hooks of specimens of H. holospinus from a new collection from the common ponyfish, Leiognathus equulus (Leiognathidae), in Quang Binh, Gulf of Tonkin, Vietnam are reported here for the first time. Additional details of the anterior trunk cone, proboscis hooks, wholly spined trunk, duck-bill-like spines with micropores, and micropore distribution, are described. The unique metal composition of hooks (EDXA) demonstrated a considerably higher level of calcium and phosphorus but lower level of sulfur at the hook basal arch than at the hook tip and edge. An analysis of our new sequences of cytochrome oxidase 1 (COI) showed that H. holospinus had low genetic variation and two haplotypes.

TITLE: Mise à jour morphologique et caractérisation moléculaire d'Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Acanthocephala, Arhythmacanthidae) de l'Océan Pacifique au large du Vietnam. ABSTRACT: Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Arhythmacanthidae) a été décrit pour la première fois chez le poisson-chat Plotosus lineatus (Plotosidae) dans la baie d'Halong, au Vietnam. Des nouvelles informations morphologiques, des images au microscope électronique à balayage, une analyse moléculaire et une analyse par rayons X à dispersion d'énergie (EDXA) des crochets de spécimens d'H. holospinus provenant d'une nouvelle récolte de Leiognathus equulus (Leiognathidae), à Quang Binh, golfe du Tonkin, Vietnam sont données pour la première fois. Des détails supplémentaires sur le cône antérieur du tronc, les crochets du proboscis, le tronc entièrement épineux, les épines en forme de bec de canard avec des micropores et la distribution des micropores sont décrits. La composition métallique unique des crochets (EDXA) a démontré une teneur en calcium et en phosphore considérablement plus élevée, mais une teneur en soufre plus faible au niveau de l'arcade basale du crochet qu'à la pointe et au bord du crochet. Une analyse de nos nouvelles séquences de cytochrome oxydase 1 (COI) a montré qu'H. holospinus présentait une faible variation génétique et deux haplotypes.

Moniliformis cryptosaudi n. sp. (Acanthocephala: Moniliformidae) from the Long-eared Hedgehog Hemiechinus auritus (Gmelin) (Erinaceidae) in Iraq; A Case of Incipient Cryptic Speciation Related to M. saudi in Saudi Arabia.

Moniliformis cryptosaudi n. sp. (Moniliformidae) is an acanthocephalan described from the long-eared hedgehog Hemiechinus auritus (Gmelin) (Erinaceidae) in Iraq as an incipient cryptic species of Moniliformis saudi Amin, Heckmann, Mohammed, Evans, 2016 described from the desert hedgehog Paraechinus aethiopicus (Ehrenberg) (Erinaceidae) in Saudi Arabia. Microscopical studies demonstrate that the two species are morphologically indistinguishable with practically identical measurements and counts but differed significantly in their energy dispersive X-ray analysis (EDXA) of metal composition of hooks. Hooks of specimens of the new species appeared to be of collagen material with very low levels of phosphorus and calcium unlike those of M. saudi and Moniliformis kalahariensis Meyer, 1931 that had high levels of calcium and phosphorus. Using 18S rDNA and cox1 genes, M. Saudi and M. kalahariensis were shown to be molecularly distinct but the molecular profiles of M. saudi and M. cryptosaudi were more similar. The molecular profile of M. kalahariensis collected from the South African hedgehog Atelerix frontalis Smith (Erinaceidae) in South Africa is reported for the first time and is studied only for comparative purposes. Moniliformis saudi and M. kalahariensis had comparable EDXA metal analysis that was distinct from that of M. cryptosaudi.

Cavisoma magnum (Cavisomidae), a unique Pacific acanthocephalan redescribed from an unusual host, Mugil cephalus (Mugilidae), in the Arabian Gulf, with notes on histopathology and metal analysis.

Cavisoma magnum (Southwell, 1927) Van Cleave, 1931 was originally described from a sea bass, Serranus sp. and spotted surgeonfish, Ctenochaetus strigosus (Perciformes) off Sri Lanka before its more recent redescription from milkfish in the Philippines in 1995. These reports were based on only light infections of their host fishes. Of the few flathead grey mullets, Mugil cephalus (Mugilidae), that we examined in the Arabian Gulf, one fish was infected with 1,450 worms. One milkfish, Chanos chanos (Chanidae), from the same location in the Arabian Gulf, was also heavily infected with specimens of C. magnum. The descriptions of this unique large worm are revised and for the first time, we provide SEM images, new systematic observations, metal analysis of hooks showing extremely high levels of sulfur, and histopathology in the mullet intestinal tissue. Adjustments and corrections of previous descriptive accounts are made. The histopathology studies show extensive damage to the host intestinal tissue including epithelial necrosis, hemorrhaging and worm encapsulation. There is an extensive amount of host connective tissue surrounding the worm. Results of x-ray analysis displayed high levels of sulfur in proboscis hooks, especially at the tips and edges of these attachment structures.

Neoandracantha peruensis n. gen. n. sp. (Acanthocephala, Polymorphidae) described from cystacanths infecting the ghost crab Ocypode gaudichaudii on the Peruvian coast.

The cystacanths of Neoandracantha peruensis n. gen. n. sp. are described from the ghost crab Ocypode gaudichaudii collected from the Pacific coast of Peru. While it is uncommon to describe acanthocephalan taxa from immature stages, the presence of clear-cut distinguishing features separating the present material from its nearest congeneric taxa, and the absence of adults, justifies the erection N. peruensis. The new genus is distinguished by having three separate fields of trunk spines. Specimens of N. peruensis have a slender trunk with two anterior swellings, 3 separate fields of spines on the foretrunk swelling, and no genital spines on the hindtrunk. The proboscis of the new species is heavily armored with 21-22 longitudinal rows of 22 hooks each. Hook no. 14 is more robust ventrally than dorsally. Cystacanths of N. peruensis also have a long tubular hindtrunk and the males have diagonal testes in the midtrunk swelling. Specimens of the closely related Andracantha Schmidt, 1975 have anteriorly enlarged pear-shaped Corynosoma-like trunks, only two fields of anterior trunk spines with occasional genital spines, and bilateral or tandem testes. Proboscides of species of Andracantha have considerably fewer hooks that gradually decrease in size posteriorly. The taxonomic component of this work is amplified by metal analysis of hooks and spines that shows a marked amount of magnesium (Mg) in hooks but not in spines. The highest level of sulfur (S) was found in the outer layer of hooks and anterior spines. The metal footprint of hooks and spines varies in different species of acanthocephalans and has an interspecific diagnostic value.

Rhadinorhynchus oligospinosus n. sp. (Acanthocephala, Rhadinorhynchidae) from mackerels in the Pacific Ocean off Peru and related rhadinorhynchids in the Pacific, with notes on metal analysis.

Specimens of a new species of Rhadinorhynchus Lühe, 1911 are described from the chub mackerel Scomber japonicus (Scombridae) and the Chilean Jack mackerel Trachurus murphyi (Carangidae) (possibly a subspecies of Trachurus symmetricus) from the Pacific Ocean off the Peruvian coast at the Port of Chicama, La Libertad. Specimens of Rhadinorhynchus oligospinosus n. sp. are somewhat small having 11-14 rows of alternating proboscis hooks with 20-22 hooks each with posteriormost hooks in a continuous ring. Ventral hooks are robust with prominent roots but dorsal hooks are slender and shorter with discoid roots. Trunk spines are in two zones separated by a non-spiny region. Anterior trunk spines are in 2-3 complete circles but posterior spines are only ventral and lateral, and do not extend posterior to the level of the posterior end of the proboscis receptacle in both sexes. The new species is closest to Rhadinorhynchus seriolae (Yamaguti, 1963) Golvan, 1969 found in Japanese and Australian waters, but not as close to 19 other species found in the same Pacific waters off Australia, Japan, and Vietnam. In R. seriolae, posterior trunk spines extend well past the receptacle in females, among other diagnostic differences. Proboscis hooks of the new species were analyzed for chemical elements using X-ray in conjunction with EDAX (energy-dispersive analysis for X-ray) software; sulfur had a higher concentration at the edge than the middle of cut hooks.