Seasonal transmission ofRaphidascaris acus (Nematoda), a parasite of freshwater fishes,in definitive and intermediate hosts

Synopsis The seasonal transmission ofRaphidascaris acus was studied in two small lakes on Manitoulin Island, Ontario. Dragonfly nymphs and caddisfly larvae, acting as paratenic hosts, contained second-stage larvae. Several fishes, including percids and cyprinids, were intermediate hosts with second, third, and fourth-stage larvae in the liver. Yellow perch,Perca flavescens, was the most important of these. Intensities were up to 928 and increased with length and age of the perch; prevalence was 100%. Abundance ofR. acus tended to be higher in females but was not related to condition of the perch. Second-stage larvae were acquired from invertebrates in summer and developed to the fourth stage by November. They became surrounded by fibrous capsules during the next summer but remained alive for at least another year. The longevity of larvae in the intermediate host may ensure survival of the parasite through periods of low host abundance after winterkill. Northern pike,Esox lucius, was the definitive host. Abundance ofR. acus tended to be greater in larger pike but was not related to sex or condition of the fish. The parasite was acquired in late fall. Prevalence was 100% and mean intensities were over 200 in winter and spring, declining to 64–100% and less than 15, respectively, in summer. Mature worms were present from early spring through summer. Seasonality of infection in the definitive host is not attributable to seasonal availability of larvae in perch. Instead it may be controlled by timing of predation on perch and rate of development and longevity of the parasite. Transmission to pike apparently continues in summer. Low intensity may result from low recruitment rate and rapid turnover of the parasite population.     

The morphology and systematics of Rhabdochona paski Baylis, 1928 (Nematoda: Rhabdochonidae), a widespread parasite of freshwater fishes in Africa

Nematodes of the genus Rhabdochona Railliet, 1916, identified as R. paski Baylis, 1928, were collected from the intestine of Hydrocynus forskahlii (Cuvier) (Characiformes: Alestidae), Oreochromis niloticus (Linnaeus) and Tilapia zillii (Gervais) (both Perciformes: Cichlidae) from Lake Turkana, Kenya during 2007–2009. Their morphology was studied in detail using light and scanning electron microscopy. Paratypes of R. paski and museum specimens of R. congolensis Campana-Rouget, 1961 from six other host species were examined for comparison. Based on these studies and the available literature data, Rhabdochona congolensis, R. aegyptiaca El-Nafar & Saoud, 1974 (emend.) and R. vesterae Boomker & Petter, 1993 are considered to be junior synonyms of R. paski. The occurrence of this widely distributed African nematode in many fish species belonging to different families and orders suggests that most of them are probably not definitive hosts of this parasite, but only serve as paratenic, paradefinitive or postcyclic hosts (sensu Odening, 1976). True definitive hosts of R. paski appear to be characiform species belonging to some genera (e.g., Alestes, Brycinus, Hydrocynus) of the family Alestidae.     

Studies on Procamallanus (Spirocamallanus) Pereirai annereaux, 1946 (Nematoda: Camallanidae), with new host records and new morphological data on the larval stages.

Larval stages and adults of Procamallanus (Spirocamallanus) pereirai Annereaux, 1946 are described from naturally infected Paralonchurus brasiliensis (Steindachner) (Sciaenidae) from the coast of the State of Rio de Janeiro, Brazil. The translucent first-stage larvae have a denticulate process at the anterior end, no buccal capsule or esophagus undifferentiated into anterior muscular and posterior glandular parts and an elongate tail; third-stage larvae have a tail with three terminal projections, a buccal capsule divided into an anterior portion with 12-20 ridges running to the left and a posterior smooth portion, and an esophagus with muscular and glandular regions. Fourth-stage larvae exhibit a buccal capsule lacking a distinct basal ring with ridges running to the right and a tail with two terminal processes, as in adults. New host records are reported and their role in its life-cycle are discussed.     

Female morphology and systematic status of Philometroides cyprini (Nematoda: Philometridae), a parasite of carp

Gravid females of Philometroides were found under the scales of stock carp Cyprinus carpio L. imported from Lithuania to the Czech Republic in the spring of 1997 and kept in a quarantine pond. These specimens and those obtained from pond-cultured carp in Russia (Moscow district) were used for detailed morphological studies, including scanning electron microscopy. The results confirm that the valid name of this parasite is Philometroides cyprini (Ishii, 1931), whereas Philometra lusii Vismanis, 1962, Philometra schikhobalowae Belous, 1965, Philometra lusiana Vismanis, 1966 and Philometroides lusiana (Vismanis, 1966) Ivashkin et al., 1971 are its junior synonyms. P. cyprini, the agent of a serious disease of carp, seems to have been originally distributed in east Asia, from where it was introduced into Europe in the early 1960s.     

Proteomic analysis of the pinworm Syphacia muris (Nematoda: Oxyuridae), a parasite of laboratory rats

Syphacia muris (Nematoda: Oxyuridae) is a ubiquitous nematode that commonly infects rats in the laboratory which can interfere in the development of biological assays. The somatic extract of S. muris adults collected from infected rats was investigated using a proteomic approach. A shot-gun liquid chromatography/tandem mass spectrometry procedure was used. We used the MASCOT search engine (Matrix-Science) and ProteinPilot software v2.0 (Applied Biosystems) for the database search. A total of 359 proteins were accurately identified from the worms. The largest protein families consisted of metabolic enzymes and those involved in the nucleic metabolism and cell cycle. Proteins of transmembrane receptors and those involved in protein metabolism, chaperones, structural and motor, signalling and calcium-binding proteins also were identified in the proteome of S. muris. Proteome array of S. muris may contribute to further elucidation of biological system of S. muris as well as host-parasite relationships.     

Redescription of Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 (Nematoda: Camallanidae) and its first record from fishes in China

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13-16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.     

First record of Huffmanela schouteni (Nematoda: Trichosomoididae), a histozoic parasite of flyingfishes, in Europe

Examination of 3 specimens of the Mediterranean flyingfish Cheilopogon heterurus (Rafinesque) from the Ligurian Sea, Italy, revealed the presence of numerous, dark-shelled trichinelloid eggs (69 to 75 x 30 to 33 microm) inside the innermost layer of the swimbladder, mostly located in clumps arranged in a distinct pattern. These were identified as Huffmanela schouteni Moravec et Campbell, 1991, a species known so far as eggs in flyingfishes and in the stools of humans in Cura?ao. This is the first finding of this parasite in Europe and C. heterurus represents a new host record.     

Redescription of Cosmocephalus tanakai Rodrigues & Vicente (Nematoda: Acuariidae), a parasite of the southern black-backed gull in New Zealand

Abstract

Cosmocephalus tanakai is redescribed from specimens found in the oesophagus of Larus dominicanus from the South Island of New Zealand. The male is characterised by nine pairs of pedunculate subventral caudal papillae plus two pairs of sessile papillae, and a pair of bicuspid papillae three-quarters of the way down the body. The female too has the pair of posteriad bicuspid papillae, plus a button-like terminal caudal process. A key to the species of Cosmocephalus is given.     

Cold-hardiness in Pelecitus fulicaeatrae (Nematoda: Filarioidea), a parasite of the ankles of Fulica americana (Aves).

The filarioid nematode Pelecitus fulicaeatrae (Diesing, 1861) is considered cold-hardy. Adults and microfilariae became motile when placed in saline at 22 C after having been removed from thawed carcasses of their host, the American coot (Fulica americana Gmelin) (Aves: Gruiformes). Adult nematodes from 5 of 12 carcasses became active as did microfilariae from 4 of 5 carcasses. Carcasses had been frozen at an undetermined temperature below 0 C for an initial 14 days and then at -21 to -24 for 100-159 days.     

Redescription of Enterobius anthropopitheci (Gedoelst, 1916) (Nematoda,Oxyurida), a parasite of chimpanzees

Enterobius anthropopitheci (Gedoelst, 1916), a parasite of the chimpanzees Pan troglodytes and P. paniscus, is redescribed. E. anthropopitheci can be distinguished from the two closely related species parasitic in man, E. vermicularis (L., 1758) and E. gregorii Hugot, 1983, by the following characters: in the males, the cuticular pericloacal ornamentation, and the size and shape of the spicule; in the females, the lateral alae, which are simple in the pinworms of man, are simple only anteriorly and divided into two crests at the mid-oesophageal level in the parasite of chimpanzees. Enterobius anthropopitheci (Gedoelst, 1916), parasite des chimpanzés, Pan troglodytes et P. paniscus, dans toute leur aire de répartition est redécrite. E. anthropopitheci est très proche par sa morphologie des deux oxyures de l'Homme, E. vermicularis (L., 1758) et E. gregorii Hugot, 1983, dont il diffère toutefois par les caractères suivants: chez le mâle, ornementation cuticulaire péricloacale, taille et forme du spicule; chez la femelle, aile latérale simple sur toute sa longuer chez les oxyures de l'Homme, simple dans la région antérieure se dédoublant en deux crêtes au milieu de l'oesophage, chez l'oxyure parasite des chimpanzés.     

The development and morphogenesis of Camallanus cotti Fujita, 1927 (Nematoda: Camallanidae), with notes on its phylogeny and definitive host range

The freshwater fish nematode Camallanus cotti Fujita, 1927 (Spirurida: Camallanidae) is naturally distributed in East, South and Southeast Asia. During the past three or four decades the species has been disseminated to Europe, North America, Australia and Hawaii, mainly due to the extensive ornamental fish trade. In the present study, its development and larval morphogenesis is described. Newborn first-stage larvae are ingested by copepods and within hours reach the haemocoel, where the worms moult twice. At 22°C ambient temperature, fully-developed third-stage larvae appear on day 11 p.i. After transmission into the fish intestine two further moults occur before the adult stage is reached. At 23°C water temperature, the final moult is initiated around day 33 p.i. in males and between 34 and 42 days p.i. in females. Morphologically the young and older adults are similar, but the buccal capsule of both young males and young females is not yet fully sclerotised. Based on the close similarity in the development and adult morphology of the buccal capsule in C. cotti and three congeners from Europe and North America, we suggest, in general agreement with earlier workers, that the Camallanus Railliet & Henry, 1915 originated in tropical Asia and subsequently radiated to species when adapting to new climatic and/or host-related conditions in the Old World and the New World. C. cotti may thus represent a lineage of speciation which did not apparently involve extensive changes in relation to their natural geographical distribution or definitive host range.     

The life history of Sulcascaris sulcata (Nematoda: Ascaridoidea), a parasite of marine molluscs and turtles

Berry G. N. and Cannon L. R. G. 1981. The life history of Sulcascaris sulcata (Nematoda: Ascaridoidea), a parasite of marine molluscs and turtles. International Journal for Parasitoiogy11: 43–54. The morphology, development and hatching of Sulcascaris sulcata eggs are described. Two moults occurred in the egg. Third stage larvae spontaneously hatched and were found to develop in marine bivalves and gastropods. Larvae grew steadily and after three to four months, when about 5 mm long, they moulted to fourth stage larvae characteristic of natural infections in bivalves from commercial catches. Experimentally, when fed to laboratory-reared Caretta caretta, the fourth stage larvae first attached at the oesophago-gastric junction where they moulted to adults in 7–21 days. Subsequent growth to mature adults was obtained by at least 5 months after infection. It is suggested that under natural conditions the life history may take up to 2 years to complete. These findings are discussed in relation to the predatory mode of feeding and the breeding habits of C. caretta and the significance of a possible health hazard to man.     

A new species of Procamallanus (Nematoda: Camallanidae) from Pacific eels (Anguilla spp.)

A new species of parasitic nematode, Procamallanus (Procamallanus) pacificus n. sp., is described from the stomach of the Pacific shortfinned eel, Anguilla obscura (type host), and from the speckled longfin eel, Anguilla reinhardtii, from northern New Caledonia (Melanesia, South Pacific); from Anguilla sp. (cf. obscura) from the Fiji Islands (Melanesia, South Pacific); and from the giant mottled eel Anguilla marmorata from Futuna Island (Wallis and Futuna Islands, Polynesia). Although a total of 450 nematodes were collected, all specimens were females; this suggests either an extremely rare occurrence of males or parthenogenetic reproduction in this species. Procamallanus pacificus differs markedly from all congeners from fish hosts in possessing a greater number (4-9) of caudal mucrons in the female and by other morphological features. This parasite might become a serious pathogen of cultured eels in the region of the South Pacific. Batrachocamallanus Jackson and Tinsley, 1995 is considered a junior synonym of Procamallanus Baylis, 1923, to which 2 species are transferred as Procamallanus occidentalis (Jackson and Tinsley, 1995) n. comb. and Procamallanus siluranae (Jackson and Tinsley, 1995) n. comb. One third-stage larva of Procamallanus (Spirocamallanus) sp. was also recorded from Anguilla sp. (cf. obscura) from the Fiji Islands.     

Morphology of Philometroides barbi (Nematoda: Philometridae), a rare tissue parasite of the Mediterranean barbel Barbus meridionalis (Osteichthyes)

A female specimen of the nematode Philometroides barbi Moravec, Simková, Hanzelová, Spakulová et Caki?, 2005, a little-known histozoic parasite of the Mediterranean Barbus meridionalis, was recorded from the fin of its fish host in Bulgaria. Scanning electron microscopical examination, used for the first time in this species, made it possible to determine the character of cephalic papillae (14 papillae arranged in 2 circles) and amphids and confirmed the presence of 4 large caudal lobes. These features distinctly distinguish P. barbi from Philometroides cyprini and other congeners parasitizing European fishes.     

The evolution of thunniform locomotion and heat conservation in scombrid fishes: New insights based on the morphology of Allothunnus fallai

Two significant functional differences–a more anterior and internally positioned red myo‐tomal muscle mass and modification of the red‐muscle vascular supply to form counter‐current heat exchangers–distinguish the tunas (tribe Thunnini) from other species in the teleost family Scombridae. Neither of these characteristics is found in the bonitos (tribe Sardini), the sister group to the Thunnini. The most recent scombrid classification places the slender tuna, Allothunnus fallai, in the tribe Sardini, but some earlier studies suggested that this species should be a member of the Thunnini. Allothunnus fallai does not possess the lateral subcutaneous arteries and veins or the lateral heat‐exchanging retia typical of tunas. However, we have found that this species has a highly modified central circulation (dorsal aorta, post cardinal vein, and associated branch vessels) similar to the central heat‐exchanging retia of certain tunas, an enlarged haemal arch to accommodate this structure, and the anterior, internal placement of red muscle characteristic of tunas. With these new characters, phylogenetic reconstructions based on parsimony place A. fallai as the sister taxon to the tunas, establish that it is the most basal tuna species, and support the hypothesis that the derivation of tunas from a bonito‐like ancestor occurred through selection for an integrated set of characteristics affecting locomotion and endothermy. The major features of this hypothesis are as follows. (1) Selection for continuous, steady, and efficient swimming resulted in changes in body shape (the result of enlargement of the anterior myotomes, the anterior and internal shift of red muscle, and a narrowing of the caudal peduncle) which increased streamlining and led to the adoption of the thunniform swimming mode unique to the tunas. (2) Alterations in blood supply necessitated by the anterior shift in red muscle led to the interdigitation of numerous arterial and venous branches which set the stage for heat conservation. (3) The evolution of endothermy, together with thunniform swimming, contributed significantly to the ecological radiation and diversification of tunas during the Early Tertiary Period. Our studies of A fall thus suggest that the shift in red muscle position and changes in central circulation preerded the evolution of red‐muscle endothermy. Co‐evolutionary changes in red muscle quantity and distribution and in vascular specializations for heat conservation have led to different macroevolutionary trajectories among the now five genera and 14 tuna species of tunas and appear to reflect the influence of changing paleocological and paleoccanographic conditions, including cooling, that occurred in the Tertiary