A new species of Afrolernaea (Copepoda: Lernaeidae) parasitic on mormyrid fishes in Gabon and a discussion of its affinities

A new lernaeid copepod of the genus Afrolernaea parasitic on mormyrid fishes from Gabon is described. A fin parasite, this species has been found only on the inner face of the pectoral fins. The new species is the most primitive member of the genus yet discovered and the structure of its appendages throws light on the nature of the anchoring hooks of the more advanced species, and on the probable course of evolution within the genus. The suggested affinities of the species of the genus are indicated in a dendrogram.     

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.     

Comparison of the parasitic fauna of Aplocheilus panchax and A. melastigma

The metazoan parasite fauna of two species of freshwater fishes Aplocheilus panchax and A. melastigma collected from a stream at Waltair is compared; 17 parasite species were found. Aplocheilus panchax served as a host to 13 parasite species and A. melastigma to 10 parasite species. Of the 17 parasites collected, 12 were larval helminths to which the fishes act as intermediate and paratenic hosts. This has been attributed to the interaction between terrestrial birds, mammals and fishes in determining the parasite fauna in the biocoenosis. The parasite fauna of these fishes is divided into typical and less typical according to their frequencies. Among less typical there are peripheral division parasites which are abundant in other fishes in the stream. Only six parasite species occurred in both A. panchax and A. melastigma and both fish shared most of their parasite fauna with other fishes. Differences in the parasite fauna of these fishes are attributed to the morphological, behavioural or ecological features of these fishes.     

Cystacanths of Acanthocephala in notothenioid fish from the Beagle Channel (sub-Antarctica)

The morphology of relaxed cystacanths of polymorphid acanthocephalans collected from notothenioid fishes in the Beagle Channel (Magellanic subregion of sub-Antarctica) is described. A parasite of birds, Andracantha baylisi (Zdzitowiecki, 1986), was found in Patagonotothen longipes and Champsocephalus esox. It has: a proboscis 0.82–0.89 mm long; a proboscis hook formula of 16 rows of 9/10–10/11, including 4–5 basal hooks; distal hooks with the longest blades; a fore-trunk not separated from the hind-trunk by a constriction; large somatic spines arranged in two zones separated by a zone of small, loosely dispersed spines; and only the anterior 36–40% of ventral side of the trunk is covered with spines. One male specimen of Corynosoma sp. was found in Patagonotothen tessellata. It differs from A. baylisi in that the distal proboscis hooks are similar in length to the prebasal hooks, it has a smaller proboscis (0.77 mm) and in the distribution of the somatic spines, which are contiguous with the genital spines on the ventral side of the trunk and lack a zone of small spines between zones of larger spines. A parasite of seals and fur seals, Corynosoma evae Zdzitowiecki, 1984, was found in P. longipes and Champsocephalus esox. It has: a proboscis 0.61–0.78 mm long; a proboscis hook formula of 20–22 rows of 12–13, including 3/4–4 basal hooks; prebasal hooks with the longest blades; a trunk divided into fore-trunk and hind-trunk; somatic spines covering the anterior 64–74% of the ventral side of the trunk; genital spines present only in males; and a terminal genital opening in both sexes. Corynosoma beaglense n. sp. was found in Champsocephalus esox. It has: an almost cylindrical proboscis (length 0.52–0.56 mm); a proboscis hook formula of 16 rows of 9/10–10/11, including 4–4/5 basal hooks; distal hooks shorter than the prebasal hooks; a fore-trunk not separated from the hind-trunk by a constriction; somatic spines contiguous with the genital spines on the ventral side of the trunk of the male and covering the entire length of the ventral side of the female trunk, and the presence of genital spines surrounding the terminal genital pore of the male. The definitive host of this species is unknown.     

Community ecology of the parasites of adult spot, Leiostomus xanthurus, and Atlantic croaker, Micropogonias undulatus (Sciaenidae) in the Cape Hatteras region

Twenty-three species of metazoan parasites were recorded from adult spot and 26 from adult croaker. Of the 33 parasitic species found, 17 occurred in both spot and croaker. No significant differences in intensity of parasites occurred between sexes of either spot or croaker. All of the parasites had over-dispersed, or clumped, distributions among hosts. Adult spot and croaker collected offshore had much greater species-richness, diversity, and total number of individual parasites than juvenile fishes collected in adjoining estuaries during another study. The juvenile spot and croaker had less time to acquire parasites and inhabited less diverse and more confined habitats in inshore estuaries, which resulted in less diverse parasite communities than offshore fishes. The number of species and diversity of parasites in adult fish was greater in croaker than spot. However, when only gastrointestinal helminths were considered, spot had greater species-richness as well as greater numbers of individual helminths, suggesting that they had a more diverse diet and that they fed on more infected intermediate hosts than croaker. In both adult spot and croaker the mean number of parasitic species was greater than those of freshwater fishes and fewer than those for birds and mammals. The total number of individual parasites was similar to that of freshwater fishes. The opportunistic diet and the migratory habits of both spot and croaker contribute to their diverse parasite faunas. Comparison of adult spot and croaker parasite faunas collected offshore indicated that their respective parasite component communities were distinct and that similar parasite infracommunity variability existed in both hosts and that their communities were not ‘random’ samples, but restricted subsets of the compound community. Although the parasite dominance hierarchy in adults of both species varied slightly between areas and seasons sampled, there appeared to be a predictable dominant species that was accompanied by subordinate, less predictable species. However, the variability in both relative intensities and presence-absence of parasites within communities resulting from their diverse diets make them less predictable than those of other vertebrates with less diverse diets such as the lesser scaup duck and more like those of other marine fishes.     

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.     

Pomphorhynchus patagonicus n. sp. (Acanthocephala: Pomphorhynchidae) from freshwater fishes of Patagonia, Argentina

Pomphorhynchus patagonicus n. sp. is described from Lake Rosario, Chubut Province, Argentina. It is characterized by a long neck forming an asymmetrical bulb with 2 well differentiated dorsal protruberances and 14 alternating rows of 13 and 14 proboscis hooks, each row with a stout fourth hook. It most closely resembles Pomphorhynchus sebastichthydis Yamaguti, 1939, from Japan, but differs in the bulb protruberances and in having more rows of hooks and more hooks per row and in the shapes of the fourth and basal hooks. Among American species P. patagonicus shows some similarities to Pomphorhynchus yamagutii Schmidt and Hugghins, 1973, from Chile, but differs with respect to the longer neck, bulb protruberances, and proboscis armature. Pomphorhynchus patagonicus is endemic to Patagonia, where its definitive type host is the endemic fish Patagonina hatcheri (Atherinidae) and its intermediate host the endemic freshwater amphipod Hyalella patagonica. It has been found also in autochthonous fishes belonging to the families Galaxiidae and Percichthyidae and in introduced salmonid fishes.     

Enzymatic survey of four populations of Atherina boyeri based on electrophoresis and the occurrence of a microsporidiosis

Biochemical genetics of a Atherinid species, Atherina boyeri were undertaken to determine variability. Among the 17 loci studied, 7 were polymorphic, of which three were retained for a more detailed comparison of populations inhabiting the French Mediterranean coastal lagoons. A microsporidiosis is present in these fishes and is limited to certain lagoons. Comparison of allelic frequencies at the polymorphic loci between fish populations of infected and healthy lagoons yielded no significant differences. Several hypotheses are discussed and attempt to agree parasite distribution with genetical results.     

Echinorhynchus brayi n. sp. (Acanthocephala: Echinorhynchidae) from Pachycara crassiceps (Roule) (Zoarcidae), a deep-sea fish

Echinorhynchus brayi n. sp. (Palaeacanthocephala: Echinorhynchidae) is described from Pachycara crassiceps (Roule) (Zoarcidae) from the Porcupine Seabight, Northeast Atlantic. The new species closely resembles E. canyonensis Huffman & Kliever, 1977, a parasite of a Pacific zoarcid, but has longer lemnisci, larger eggs and larger testes. E. brayi n. sp. can be readily differentiated from the ten other Echinorhynchus spp. recorded from deep-sea fishes (E. abyssicola, E. gadi, E. longiproboscis, E. malacocephali, E. melanoglaeae, E. muraenolepisi, E. petrotschenkoi, E. sebastolobi, E. trachyrinci and E. truttae), because it has fewer hooks per longitudinal row.     

Host-specialization and species diversity in fish parasites: phylogenetic conservatism?

The pattern of parasite species diversification and specialization, appreciated by host range, is investigated in fish parasites. We test whether host range is linked with phylogeny at a high taxonomic level, and if there is a relationship between host range and host species diversification. For this purpose we used two sets of data, one on macro-parasites of marine fishes of the Mediterranean Sea and the other on macro-parasites of marine and freshwater fishes of Canada. Similar patterns of host range among parasitic groups were found. Our findings suggest that habitat (marine vs freshwater) and geographic localization (Canada vs Mediterranean region) play little role in determining the observed patterns of host range. We highlight the potential influence of phylogeny (high-taxonomic level) on the level host range in parasites. We find that parasites with free-swimming larval stages and with direct life cycles have a narrower range of host species than do parasites with indirect life cycle, even if we cannot control for phylogenetic effects because of the lack of variation of life cycles within each parasitic group. Finally, a positive relationship was found between the number of known hosts and parasite species diversity in the case of Mediterranean parasite species. The relationship between host range and species diversification should be related to the mechanism of cospeciation.     

Distribution and food habits of the slender smoothhound,Gollum attenuatus,from the waters around New Zealand

Three hundred and seventy-three females and 385 malesof Gollum attenuatus were caught with bottom longlines from the Challenger Plateau, Wanganella Bank and Three Kings Ridge around New Zealand. The sharks ranged in size from 440 to 1092 mm TL for females and 442 to 1067 mm TL for males. Catch rates (number of fish per 100 hooks) were 0.41 for the Challenger Plateau, 0.14 for the Wanganella Bank, and 4.52 for the Three Kings Ridge. The sex ratio was 1:1. In terms of 100-m depth intervals,G. attenuatus was most abundant in 500 to 599 m depths. There was a marked decrease in catch rates with increased distance of the hooks from the bottom. Stomachs contained such varied items as sharks, teleost fishes, gastropods, squids, octopi, decapods, isopods, brittle stars, and human garbage. The data in this study suggest thatG. attenuatus consumed, in order of importance, fishes and crustaceans.     

Local variability in metazoan parasites of the pelagic fish species, Engraulis ringens: implications for fish stock assessment using parasites as biological tags

Parasites have been used successfully as biological tags in population studies, mainly in marine fishes, but also in marine mammals, crustaceans and molluscs. Almost all published information dealing with parasites as biological tags evaluates differences between localities. However, local variability in the component community has not been assessed. In this work, we examined whether local variation of the metazoan parasite fauna of Engraulis ringens, extracted from five independent samples from two nearby localities in northern Chile, can be a factor causing bias in stock identification. Our results show that local variability, as estimated by a single sample, may suffice to represent component community variability with no need for replicated data.     

Parasites of coral reef fish larvae: its role in the pelagic larval stage

The pelagic larval stage is a critical component of the life cycle of most coral reef fishes, but the adaptive significance of this stage remains controversial. One hypothesis is that migrating through the pelagic environment reduces the risk a larval fish has of being parasitised. Most organisms interact with parasites, often with significant, detrimental consequences for the hosts. However, little is known about the parasites that larval fish have upon settlement, and the factors that affect the levels of parasitism. At settlement, coral reef fishes vary greatly in size and age (pelagic larval duration), which may influence the degree of parasitism. We identified and quantified the parasites of pre-settlement larvae from 44 species of coral reef fishes from the Great Barrier Reef and explored their relationship with host size and age at settlement, and phylogeny. Overall, less than 50% of the larval fishes were infected with parasites, and over 99% of these were endoparasites. A Bayesian phylogenetic regression was used to analyse host-parasite (presence and intensity) associations. The analysis showed parasite presence was not significantly related to fish size, and parasite intensity was not significantly related to fish age. A phylogenetic signal was detected for both parasite presence and intensity, indicating that, overall, closely related fish species were likely to have more similar susceptibility to parasites and similar levels of parasitism when compared to more distantly related species. The low prevalence of infection with any parasite type and the striking rarity of ectoparasites is consistent with the ‘parasite avoidance hypothesis’, which proposes that the pelagic phase of coral reef fishes results in reduced levels of parasitism.

     

The family Tetraonchidae (Monogenea): its structure and position among the monogeneans

The muscle fascicles of the haptor in Tetraonchus monenteron have been described. The muscle connection of the fan-shaped dorsal bars with dorsal anchors is shown. When these muscle fascicles are contracted the dorsal anchors works as pincers. The division of tetraonchids into two genera based on types of copulatory organs, morphology of bars and haptor ans associations with different groups of fishes is restored. Different authors based on ciliated cells and chaetotaxy of the oncomiracidium and comparative spermiogenetic of T. monenteron include the tetraonchids with 16 marginal hooks into the order Dactylogyroidea. In the same time, based on the analysis of the onthogenesis of the dactylogyrid's haptor they postulate, that the haptor of these worms originally had 2 pairs of anchors and only 14 marginal hooks. The present paper contains data indicating that different representatives of the Dactylogyridea have 14-18 marginal hooks. Author put forward a suggestion, that some group of dactylogyrids originally did not have the anchors.     

Two new species of Macrobothridium (Cestoda: Diphyllidea) from rhinobatid elasmobranchs in the Gulf of Gabès, Tunisia, with notes on the status of the genus.

As a result of an investigation of metazoan parasites of elasmobranch fishes in the Gulf of Gabès, Tunisia, we discovered 2 new species of diphyllidean cestodes. Macrobothridium euterpes n. sp. is described from the spiral intestine of Rhinobatos rhinobatos, and Macrobothridium syrtensis n. sp. from the spiral intestine of Rhinobatos cemiculus. Macrobothridium euterpes is distinguished from the only other species in the genus (Macrobothridium rhynchobati) by the number of rostellar hooks, size, genital pore position, vagina position, and ovary shape. Macrobothridium syrtensis is distinguished from M. rhynchobati by the hook morphology, testis number, and overall size, and from M. euterpes by the number of rostellar hooks, testis number, genital pore position, vagina position, and ovary shape. These are the first 2 species added to the genus since its establishment in 1989. A standardized formula for representing the number and arrangement of rostellar hooks in diphyllidean species is presented.     

Parasite fauna of the snakehead Channa argus warpachowskii from Primorsky Krai

Parasite fauna of the snakehead Channa argus warpachowskii was studied in water bodies of Primorsky Krai. Thirty-one parasite species were recorded in this host from the studied area according to original and literary data. Most part of these species are host-specific parasites of snakehead originated from Chinese-Indian region or parasites having a wide host range and able to infest almost all freshwater fishes. Moreover, three brackishwater species of parasites were found in the fishes introduced into the rivers of the southern part of Primorsky Krai. The causes of this invasion are discussed.     

Parasites of native and exotic freshwater fishes in south‐western Australia

In this study, 1429 fishes of 18 different species (12 native and six exotic) were sampled from 29 localities to compare the levels of parasitism between native and exotic fish species and to examine the relationship between environmental degradation and parasite diversity. Forty‐four putative species of parasites were found and most of these appear to be native parasites, which have not previously been described. Two parasite species, Lernaea cyprinacea and Ligula intestinalis, are probably introduced. Both were found on or in a range of native fish species, where they may cause severe disease. Levels of parasitism and parasite diversity were significantly greater in native fishes than in exotic species, and this may contribute to an enhanced demographic performance and competitive ability in invading exotics. Levels of parasitism and parasite diversity in native fishes were negatively related to habitat disturbance, in particular to a suite of factors that indicate increased human use of the river and surrounding environment. This was due principally to the absence in more disturbed habitats of a number of species of endoparasites with complex life cycles, involving transmission between different host species.     

The distribution of the introduced tapeworm Bothriocephalus acheilognathi in Australian freshwater fishes

Native and exotic fishes were collected from 29 sites across coastal and inland New South Wales, Queensland and Victoria, using a range of techniques, to infer the distribution of Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) and the host species in which it occurs. The distribution of B. acheilognathi was determined by that of its principal host, carp, Cyprinus carpio; it did not occur at sites where carp were not present. The parasite was recorded from all native fish species where the sample size exceeded 30 and which were collected sympatrically with carp: Hypseleotris klunzingeri, Hypseleotris sp. 4, Hypseleotris sp. 5, Phylipnodon grandiceps and Retropinna semoni. Bothriocephalus acheilognathi was also recorded from the exotic fishes Gambusia holbrooki and Carassius auratus. Hypseleotris sp. 4, Hypseleotris sp. 5, P. grandiceps, R. semoni and C. auratus are new host records. The parasite was not recorded from any sites in coastal drainages. The only carp population examined from a coastal drainage (Albert River, south-east Queensland) was also free of infection; those fish had a parasite fauna distinct from that of carp in inland drainages and may represent a separate introduction event. Bothriocephalus acheilognathi has apparently spread along with its carp hosts and is so far restricted to the Murray-Darling Basin. The low host specificity of this parasite is cause for concern given the threatened or endangered nature of some Australian native freshwater fish species. A revised list of definitive hosts of B. acheilognathiis presented.