First report of Neoechinorhynchus (Acanthocephala: Neoechinorhynchidae) from marine fish of the eastern seaboard of Vietnam, with the description of six new species

The occurrence of acanthocephalans of the genus Neoechinorhynchus Stiles and Hassall, 1905 in Vietnamese waters is reported for the first time. Six new species are described from seven species of marine fish of the families Belonidae, Clupeidae, Megalopidae, Mugilidae, and Sciaenidae, collected in Halong Bay of the eastern seaboard of Vietnam in 2008 and 2009. These are Neoechinorhynchus (Neoechinorhynchus) plaquensis n. sp. characterized by dermal plaques covering the entire trunk; Neoechinorhynchus manubriensis n. sp. with very long anterior proboscis hooks having roots with prominent anterior manubria and very small and equal middle and posterior hooks, two pseudo-retractors in the receptacle, simple vagina, and terminal gonopore; Neoechinorhynchus pennahia n. sp. with equal anterior and middle proboscis and somewhat smaller posterior hooks, and terminal female gonopore; Neoechinorhynchus ampullata with many giant nuclei in the body wall and lemnisci and a parareceptacle structure complex which includes pumping ampullas reported for the first time; Neoechinorhynchus (Neoechinorhynchus) longinucleatus n. sp. with very long giant nuclei in the Lemnisci, anteriorly twisted vagina, and subterminal female gonopore. Neoechinorhynchus (Neoechinorhynchus) ascus n. sp. is the second species of Neoechinorhynchus found with the parareceptacle structure/ampulla complex. Neoechinorhynchus (Neoechinorhynchus) johnii Yamaguti, 1929 of Bilqees, 1972 is not N. johnii because of proboscis armature and other discrepancies with the Yamaguti material. Notes on host distribution and feeding habits are also included.     

Description and host relationships of Polymorphus spindlatus n. sp. (Acanthocephala: Polymorphidae) from the heron Nycticorax nycticorax in Peru

Polymorphus spindlatus n. sp. is described from the black-crowned night heron, Nycticorax nycticorax, in Lake Titicaca, Peru. It is distinguished from all 27 known species of the subgenus Polymorphus by its spindle-shaped proboscis and its trunk shape, the anterior 2/3 of which is ovoid, tapering into a tubular posterior end. It resembles Polymorphus brevis (=Arhythmorhynchus brevis), which is, however, longer and considerably more slender, and has smaller and more numerous proboscis hooks per row and smaller eggs. It is separated also from Polymorphus swartzi, Polymorphus striatus, Polymorphus contortus, and Polymorphus cincli by its proboscis armature (usually 18 longitudinal rows of 11-13 hooks each), among other characters. Histopathological sections of host tissue show well defined localized damage including hemorrhaging with subsequent phagocyte cell migration (granular tissue). The lumen of the host intestine is obstructed and villi show compression. The proboscis of P. spindlatus extends through the intestinal mucosa and submucosa, displacing the smooth muscle layers of the muscularis externa. Fibrosis also was observed.     

Acanthocephalus?amini n. sp. (Acanthocephala: Echinorhynchidae) from the freshwater fish Cichlasoma?urophthalmus (Günther) (Cichlidae) in Mexico

Acanthocephalus amini n. sp. (Palaeacanthocephala: Echinorhynchidae) is described from the intestine of Cichlasoma urophthalmus (Günther) (Pisces: Cichlidae) collected in the Río Champotón, a river in Campeche State, Mexico. It is the fourth species of Acanthocephalus Koelreuther, 1771 described from North American freshwater fishes, although two other species are known from South America. The new species is distinguished from other members of Acanthocephalus by features of its trunk, which is small, clavate, slightly expanded medially and bluntly pointed posteriorly. It is further distinguished by having a cylindrical proboscis armed with 13–14 longitudinal rows of 11–12 stout hooks; the apical and medial proboscis hooks are almost uniform in size and shape, decreasing in size towards the base; the posteriormost hooks are smaller, straighter and more slender than the anterior and middle hooks; and the lateral rows of hooks are more widely spaced, forming a conspicuous longitudinal area devoid of hooks. Furthermore, the lemnisci are saccate and shorter than the proboscis receptacle; and the neck is very short with a thick collar of trunk tegument, which encircles the base of proboscis. In males, the testes are in the middle third of trunk, diagonal, spherical and small relative to the body size, and there are six clavate cement glands. In females, the uterus forms a conspicuous, elongate, cylindrical egg reservoir. The new species is most similar to A. alabamensis Amin & Williams, 1983, but can be distinguished by its swollen, clavate trunk, the largest proboscis hooks being present apically and medially, smaller testes, a shorter male reproductive system relative to body size and females with a prominent uterus. They have different hosts and geographical distribution. The new species can be differentiated from Brasacanthus sphoeroides Thatcher, 2001, a similar species in a monotypic echinorhynchid genus, because the latter is larger, has smaller proboscis hooks and its lemnisci are longer than the receptacle.     

Description and morphological variability of <Emphasis Type="Italic">Neoechinorhynchus beringianus</Emphasis> n. sp. (Acanthocephala: Neoechinorhynchidae) from north-eastern Asia

Neoechinorhynchus beringianus sp. n. is described from Pungitius pungitius L. in north-eastern Russia. Since 1986, when it was first found, it was reported as 'N. pungitius Dechtiar, 1971'. However, this new species differs from the latter in having an egg shell without a prolongation of the fertilisation membrane, a larger proboscis and proboscis hooks, a subterminal position of the female genital pore and a more slender trunk, and it occurs in a different site in the intestine. N. beringianus has a small, stout body with an asymmetrical position of the proboscis, which is located ventrally to and at an angle with the longitudinal axis of the body. The proboscis is wider than long, the hooks are of equal size in each circle but diminish in size posteriorly, whereas the lemnisci are subequal in length. It differs from those species of Neoechinorhynchus Stiles & Hassall, 1905 with somewhat similar characteristics in body length, proboscis size and proportions, proboscis hook lengths, egg size, size-ratio of the cement gland and testes, and the number of giant nuclei in the tegument and lemnisci. In different geographical populations of the new species, the sizes of both the proboscis and proboscis hooks exhibit some variation.     

Neoechinorhynchus qatarensis sp. n. (Acanthocephala: Neoechinorhynchidae) from the blue-barred flame parrot fish,Scarus ghobban Forsskål, 1775, in Qatari waters of the Arabian Gulf

Neoechinorhynchus qatarensis sp. n. (Acanthocephala: Neoechinorhynchidae) is described from the marine blue-barred flame parrot fish Scarus ghobban Forssk?l, 1775 in the Arabian Gulf waters off the coast of Qatar. The new species is distinguished from all other species of the genus Neoechinorhynchus by its unique reproductive system and a glandular structure associated with the proboscis receptacle in both males and females. Other uncommon features of N. qatarensis are also discussed.     

New morphological data on the acanthocephalan <Emphasis Type="Italic">Hypoechinorhynchus magellanicus</Emphasis> Szidat, 1950 (Palaeacanthocephala: Arhythmacanthidae)

Hypoechinorhynchus magellanicus Szidat, 1950 (Acanthocephala: Arhythmacanthidae) is redescribed based on specimens collected from a sub-Antarctic notothenioid fish, Champsocephalus esox (Günther). The host was caught in the Beagle Channel (Magellanic sub-region). H. magellanicus has a trunk with an antero-dorsal curvature, a spherical proboscis, spines on the anterior region of the trunk, narrow lemnisci which are considerably longer than the proboscis receptacle, six cement glands and a single vaginal sphincter. The proboscis is armed with 40 hooks, including 15 large hooks with roots and 25 rootless basal spines. The large hooks are arranged in 10 alternate rows of one and two hooks. Each single large hook is followed by two spines, and pairs of large hooks are followed by single spines. Ten single spines are also present at the base of the proboscis between the rows. The eggs have polar prolongations of the middle envelope.     

On a new acanthocephalan family and a new order, from birds in Vietnam

During November 2000, a collection of acanthocephalans from birds in Quang Ninh Province, Vietnam, included a new genus and species in a new family and order. Pyrirhynchus heterospinus n. gen., n. sp. (Pyrirhynchidae n. fam.: Heteramorphida: new order) is described from Actitis hypoleucos (Linnaeus, 1758) (common sandpiper). The new family combines characters from Polymorphidae and Heteracanthocephalidae, and it includes new features. Specimens of the new species are distinguished from those of Heteracanthocephalidae and/or Polymorphidae by their long cylindrical trunk with anterior swelling, pyriform proboscis with hooks much larger ventrally, brain at the anterior end of the receptacle, specialized tubular cement glands, and elliptoid eggs with concentric shells. A detailed analysis of proboscis and trunk armature is included, and specimens of several species of Arhythmorhynchus Lühe, 1911 (Polymorphidae) were studied for comparative purposes. The proboscis of P. heterospinus is armed with 17 to 20 rows of 17 to 19 hooks each, with anterior 9-11 hooks rooted and posterior 6-10 spines rootless.     

Acanthocephalus tahlequahensis sp. n. (Acanthocephala: Echinorhynchidae) from the the stippled darter, Etheostoma punctulatum (Agassiz), in northeastern Oklahoma.

Acanthocephalus tahlequahensis sp. n. was recovered from the intestines of 4 species of freshwater fishes, Etheostoma punctulatum, E. spectabile, Nocomis asper, and Notropis pilsbryi, collected in northeastern Oklahoma. The new species is distinguished from all other species of Acanthocephalus, except A. japonicus (Fukui and Morisita 1936) Petrochenko 1956, and A. fluviatilus Paperna 1964, by having smaller proboscis hooks. The length of the proboscis hooks for males is 27 to 38 (33) mum and for females 35 to 46 (42) mum. A. tahlequahensis is smaller than either A. japonicus or A. fluviatilis, and has about half the number of longitudinal rows of proboscis hooks of A. japonicus and half the number of proboscis hooks in each longitudinal row of A. fluviatilus. In addition to having smaller hooks. A. tahlequahensis differs from other species of Acanthocephalus parasitizing North American fishes by its smaller, spindle-shaped trunk and more hooks in each longitudinal row.     

Spiracanthus bovichthys n. gen. n. sp. (Acanthocephala: Arhythmacanthidae), a parasite of littoral fishes of the central south coast of Chile

A new acanthocephalan species, Spiracanthus bovichthys n. gen. n. sp., is described. Samples were taken from 26 marine fish species between 23 and 53 degrees S of Chile. The parasite was found in the intestine of 6 species and only between 36 and 40 degrees S, especially in those fish that prey on small crustaceans in the upper and sublittoral zone. The parasite was found in Bovichthys chilensis (Reagan). Auchenionchus variolosus (Valenciennes), Calliclinus genigutattus (Valenciennes), Sindoscopus australis (Fowler and Bean), Myxodes cristatus Valenciennes, and Gobiesox marmoratus (Jenyns). However, only the first species is a suitable host for the parasite as evidenced by the presence of mature females. This acanthocephalan belongs to Arhythmacanthidae, but it does not correspond to any genus described. Spiracanthus bovichthys is different in the number and spiralled distribution of its hooks in the proboscis. In the short proboscis, 3 groups of hooks are distinguished according to size, summing up to 150-190 hooks. The group of largest hooks are found in the apical part of the proboscis, and there are 10 diagonal rows of small hooks from the prebasal to basal proboscis. Its trunk is covered partially by small spines. Amphipod and isopods were the prey items shared among the host fish species and are the best candidates to be the intermediate hosts of S. bovichthys.     

Amapacanthus amazonicus n. g., n. sp. (Acanthocephala: Diplosentidae: Allorhadinorhynchinae) from Arius passany and Anableps microleps (Pisces) at Maraca Island off northern Brazil

Amapacanthus amazonicus n. g., n. sp. is described from the intestine of Arius passany (Valenciennes) and Anableps microleps Müller. The most important diagnostic features are: a small globular proboscis armed with 6 diagonal rows of 3 stout hooks; middle hooks conspicuously stouter and larger than anterior ones; terminal hooks as long as middle hooks but straighter and more slender; a double-walled proboscis receptacle; a trunk bearing spines anteriorly; and two tubular cement glands in the males. Amapacanthus n. g. is differentiated from Allorhadinorhynchus, Golvanorhynchus and Slendrorhynchus, the other genera of the Allorhadinorhynchinae, by the presence of a globular proboscis armed with a small number (18) of hooks. A key to the species of the Allorhadinorhynchinae is presented.     

A review of the Arhythmacanthidae (Acanthocephala) with a description of Heterosentis hirsutus n. sp. from Cnidoglanis macrocephala (Plotosidae) in Australia

Heterosentis hirsutus n. sp. is described from Cnidoglanis macrocephala (Siluriformes: Plotosidae) from the Swan Estuary, Western Australia. It is distinguished by having 14 longitudinal rows of 6-7 hooks per row on the proboscis, a trunk armed anteriorly and posteriorly (= genital spines) with minute spines and lemnisci that may extend to the posterior margin of the proboscis receptacle. The new species also has prominent fragmented nuclei in its trunk wall. New information is given for Heterosentis plotosi Yamaguti, 1935 from Plotosus lineatus (Siluriformes: Plotosidae) and H. paraplagusiarum (Nickol, 1972) Amin, 1985 from Paraplagusia guttata (Pleuronectiformes: Cynoglossidae), both from Queensland. A key to the species of Heterosentis Van Cleave, 1931 is provided. The Arhythmacanthidae subfamilies are reviewed: there is little utility in the recognition of these taxa because of the small number of genera involved and the validity of the characters on which they are based is in doubt, particularly whether trunk spines are present or absent. Only Acanthocephaloides Meyer, 1932, Breizacanthus Golvan, 1969, Euzetacanthus Golvan & Houin, 1964, Heterosentis, Hypoechinorhynchus Yamaguti, 1939 and Paracanthocephaloides Golvan, 1969 of the Arhythmacanthidae are considered valid. A key to these genera is provided. The monotypic genus Neoacanthocephaloides Cable & Quick, 1954 is considered a new synonym of Acanthocephaloides thus creating Acanthocephaloides spinicaudatus (Cable & Quick, 1954) n. comb. Arhythmacanthus Yamaguti, 1935 is maintained as a synonym of Heterosentis because the distinction between two and three hook types is made equivocal when the transition between the apical and subapical hooks is gradual.     

Porrorchis nickoli n. sp. (Acanthocephala:: Plagiorhynchidae) from mammals in southeastern Mexico,first known occurrence of Porrorchis in the western hemisphere

Porrorchis nickoli n. sp. is described from the intestine of the gray four-eyed opossum Philander opossum (type host), the Virginia opossum Didelphis virginiana, the common opossum Didelphis marsupialis, and the white-nosed coati Nasua narica. Hosts were collected in southeastern Mexico in the Los Tuxtlas region of the state of Veracruz (type locality) and in the states of Tabasco and Chiapas. This new species is distinguished from other Porrorchis species by its small proboscis (0.286-0.428 mm long x 0.273-0.438 mm wide), a proboscis armature consisting of 22-24 vertical rows of 7 or 8 hooks per row, and the male reproductive system extending postequatorially and occupying only half of the trunk. This is the first known occurrence of a Porrorchis species in the Western Hemisphere.     

<Emphasis Type="Italic">Atactorhynchus duranguensis</Emphasis> n. sp. (Acanthocephala: Atactorhynchinae) from <Emphasis Type="Italic">Cyprinodon meeki</Emphasis> (Pisces: Cyprinodontidae) near Durango,Mexico

Atactorhynchus duranguensisn. sp. (Acanthocephala: Atactorhynchinae) is described from the intestine of Cyprinodon meeki Miller, an endemic freshwater fish from a far-inland locality of Mexico. Diagnostic features include: body small, stout, ventrally curved; small cylindrical proboscis armed with 16 alternating vertical rows of four or five hooks; anterior two or three hooks conspicuous, stout and larger than other hooks, and have large, rod-shaped roots with a markedly and abruptly enlarged base; three posterior hooks of each row are smaller and rootless; single-walled proboscis receptacle; lemnisci equal in length, elongate and robust; and cement gland syncytial, larger than testis. The new species is smaller than A. verecundus Chandler, 1935, the only previously described species in the genus. The shape of the proboscis of the new species is strikingly different from that of A. verecundus, which is widest at the apex. Likewise, the greatest width of the trunk of the new species is in about the middle, differing from that of A. verecundus where the trunk is widest posteriorly. The new species also can be distinguished from A. verecundus because of its much smaller hook lengths and slightly smaller proboscis. In addition, the proportion of large apical proboscis hooks in relation to the small basal hooks is different: the basal hooks of A. verecundus are about half the size of the anterior hooks and but only about a quarter of the size in A. duranguensis. Unlike A. verecundus, the base of the roots are markedly and abruptly enlarged in the new species. Finally, the eggs of the new species are smaller (23–27 × 8–10 m) than those of A. verecundus (27–30 × 12–13 m).     

Description of Pomphorhynchus spindletruncatus n. sp. (Acanthocephala: Pomphorhynchidae) from freshwater fishes in northern Iraq,with the erection of a new pomphorhynchid genus,Pyriproboscis n. g., and keys to genera of the Pomphorhynchidae and the species of Pomphorhynchus Monticelli, 1905

The status of species of Pomphorhynchus Monticelli, 1905 is examined and 23 species are recognised as valid. These include P. spindletruncatus n. sp., which is described herein from two species of freshwater fishes in northern Iraq, Aspius vorax Heckel and Barbus xanthopterus (Heckel) (Cyprinidae). Only one other species, P. yunnanensis Wang, 1981, has a spindle-shaped trunk similar to that of P. spindletruncatus, but is distinguished from it by a distinctly different proboscis armature. A key separating the new taxon from other species of Pomphorhynchus is included. P. heronensis Pichelin, 1997 is reassigned to a new pomphorhynchid genus, Pyriproboscis n. g., based on its unique proboscis shape and armature, short proboscis receptacle and tubular cement glands. A key to the genera of the Pomphorhynchidae is also included.     

Two new species of Moniliformis (Acanthocephala: Moniliformidae) from Malaysia

Moniliformis tarsii n. sp. was found in Tarsius bancanus. It is unique in possessing 11-12 longitudinal rows of 6-7 hooks each. Hooks 2 and 3 are conspicuously enlarged, 41-55 microns long. Moniliformis echinosorexi n. sp. differs from all other species in having 12-15 rows of 11-13 hooks that are 34-36 microns long, and in having a proboscis receptacle 1.2-2.0 mm long. Several new host records for M. moniliformis are presented.     

<Emphasis Type="Italic">Acanthocephaloides irregularis</Emphasis> n. sp. (Acanthocephala: Arhythmacanthidae) from marine fishes off the Ukrainian Black Sea coast

Acanthocephaloides irregularis n. sp. (Arhythmacanthidae) is described from four species of marine fishes in the Gulf of Odessa and Sukhyi Lyman, Ukrainan Black Sea waters, making it the tenth species of the genus. The hosts are the combtooth blenny Parablennius zvonimiri (Kolombatovic) (Blenniidae), the mushroom goby Ponticola eurycephalus (Kessler) (Gobiidae), the tubenose goby Proterorhinus marmoratus (Pallas) (Gobiidae) and the black-striped pipefish Syngnathus abaster Risso (Syngnathidae). The new species is most similar to its closest relative, Acanthocephaloides propinquus (Dujardin, 1845), in proboscis shape and armature (12 longitudinal rows of 5 hooks) and the shape of the trunk, reproductive system and lemnisci, but differs in having randomly distributed trunk spines. These trunk spines are organised in circular rings of individual spines separated by aspinose zones. The new species is also unique in having an anterior trunk collar, a very large triangular cephalic ganglion, nucleated pouches at the posterior end of the proboscis receptacle, and hooks and spines with roots bearing anterior manubria. Valid and invalid species of Acanthocephaloides Meyer, 1932 are listed and a key to all ten species is included.     

Acanthocephaloides cyrusi n. sp. (Acanthocephala: Arhythmacanthidae) from southeast African teleost fishes

A new species,Acanthocephaloides cyrusi, is described from the fishesSolea bleekeri andPomadasys commersoni from Lake St. Lucia, Natal, South Africa. It is distinguished from the other species in the genus by the more marked sexual dimorphism in length, the arrangement of hooks, the proboscis with the longest hooks at the anterior-most extremity and the greater size of the proboscis hooks and body spines. An acanthella, which may represent this species, was found in the tanaidApseudes digitalis.     

Investing in attachment: evolution of anchoring structures in acanthocephalan parasites

Secure attachment to host tissues is essential for survival and reproduction in parasitic organisms. The production of elaborate attachment structures must be costly, however, and investments in attachment should be approximately proportional to the likelihood that a parasite will be dislodged. In the present study, relative investments in attachment as a function of body size and the type of host used were examined across 138 species of acanthocephalans. These worms live anchored to the intestinal wall of a vertebrate host by inserting their hooked proboscis into host tissues. Taking proboscis volume into account, there is a negative interspecific relationship between the number of hooks borne on the proboscis and their mean length, reflecting a trade‐off between hook number and hook length. This supports the assumption that hooks are costly to produce, because any given species cannot simultaneously maximize both the relative number and relative length of the hooks it produces. There is a positive relationship between total worm size and total hook length, but it is weak, with a slope indicating that, as total body volume increases, total hook length also increases but at a slower rate. Indeed, relative investments in attachment, measured as hook length per unit body volume, decrease as worm size increases. Independently of total body size, investments in hook production are higher in species exploiting endothermic hosts, especially birds, than in those living in ectothermic hosts. Given the greater amounts of food passing through the gut of endotherms, and the richer and denser communities of intestinal parasites that they harbour, they are likely to select for greater investments in attachment. These results support the prediction that investments in attachment are influenced by the probability of being dislodged, and allow comparisons with other groups of intestinal parasites such as cestodes or trematodes. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 637–645.