Environmental factors affecting monogeneans parasitic on freshwater fishes

The environmental factors that act on fish parasites have received increasing attention in recent years. The effects of changing environmental conditions on parasite communities can provide valuable information on the effects of pollution on the ecosystem as a whole. This, of course, demands that we have a detailed knowledge o f parasite communities and the mechanisms acting upon them in a variety of natural conditions. Here, Mari Koskivaaro looks at those environmental factors that affect monogeneans parasitic on freshwater fishes.     

A list of monogeneans from Chinese marine fishes

This paper contains a brief history of studies on monogeneans of Chinese marine fishes and a list of 337 monogenean species, together with their marine hosts and notes on the sea in which they were found. An additional 139 species have been added to the 198 species recorded in `Monogeneans of Chinese Marine Fishes' published by Zhang, Yang and Liu in 2001.     

Taxonomy of monogeneans of deep sea fishes in southeastern Australia

The following monogeneans from deepwater fish in southeastern Australia are described, based on a survey of 1,563 fish (66 or 67 species, 35 families, 15 orders): Reimericotyle ceratoscopeli from Myctophum phengodes, M. hygomi, Hygophum hygomi and Ceratoscopelus warmingii; Diclidophora tubiformis n. sp. from Coryphaenoides serrulatus and C. subserrulatus; Diclidophora sp. from Lepidorhynchus denticulatus; Polycliphora nezumiae from Coryphaenoides serrulatus; Paracyclocotyla sp. from Lepidion microcephalus; juvenile Paracyclocotyla sp. from Hoplostethus atlanticus; Polyipnicola hygophi from Hygophum hygomi, Notoscopelus resplendens, Electrona risso and Myctophum phengodes; Diclidophoropsis sp. from Nezumia sp.; Eurysorchis manteri from Hyperoglyphe sp.; Heteraxinoides sp. from Synagrops japonicus; Megalocotyle helicoleni from Helicolenis papillosus. The following species are recorded but not described: Allocotylophora polyprionum (Diclidophoroidea), four unidentified species of the Diclidophoroidea from Diastobranchus capensis, both Hoplostethus atlanticus and H. intermedius, Chlorophthalmus sp. and Synagrops japonicus, respectively, one species of the Capsaloidea from Enoplosus armatus, one species of the Capsalidae from Lepidotrigla argus, one species of the Dactylogyrinae from Atypichthys strigatus, and one species of the Ancyrocephalinae from Chlorophthalmus nigripinnis.     

Cytogenetical studies in five Atlantic Anguilliformes fishes

The order Anguilliformes comprises 15 families, 141 genera and 791 fish species. Eight families had at least one karyotyped species, with a prevalence of 2n = 38 chromosomes and high fundamental numbers (FN). The only exception to this pattern is the family Muraenidae, in which the eight species analyzed presented 2n = 42 chromosomes. Despite of the large number of Anguilliformes species, karyotypic reports are available for only a few representatives. In the present work, a species of Ophichthidae, Myrichthys ocellatus (2n = 38; 8m+14sm+10st+6a; FN = 70) and four species of Muraenidae, Enchelycore nigricans (2n = 42; 6m+8sm+12st+16a; FN = 68), Gymnothorax miliaris (2n = 42; 14m+18sm+10st; FN = 84), G. vicinus (2n = 42; 8m+6sm+28a; FN = 56) and Muraena pavonina (2n = 42; 6m+4sm+32a; FN = 52), collected along the Northeastern coast of Brazil and around the St Peter and St Paul Archipelago were analyzed. Typical large metacentric chromosomes were observed in all species. Conspicuous polymorphic heterochromatic regions were observed at the centromeres of most chromosomes and at single ribosomal sites. The data obtained for Ophichthidae corroborate the hypothesis of a karyotypic diversification mainly due to pericentric inversions and Robertsonian rearrangements, while the identification of constant chromosome numbers in Muraenidae (2n = 42) suggests a karyotype diversification through pericentric inversions and heterochromatin processes.     

The occurrence of monogeneans of the subfamily Capsalinae (Capsalidae)--parasites of marine fishes

The data on an occurrence of capsalines in marine fishes are analyzed. 33 capsaline species among 55 recently known species are monoxienous, that points to the high specialization of these monogeneans. The majority of species are recorded from three subfamilies of perciform fishes: Scombridae, Istiophoridae, Xiphiidae. Possible factors causing the high specificity in monogeneans are discussed.     

Ecological succession of parasitic fauna of fishes in lakes

Succession of fish parasite fauna in lakes (with example of Baltic shield) was investigated. At the middle oligotrophic stage, the fauna of parasites and fishes maintain a relative stability for a long period and characterised by maximum species diversity.     

Analysis of parasitic communities in fishes from Lake Baikal

Analysis of infracommunities and component communities of fish parasites in Lake Baikal has been conducted for the first time. It has been revealed that parasite infracommunities for the majority of Baikal fishes are weakly balanced and impoverished (the Berger-Parker Index is > 0.5; Evension is < 0.5; the Brillouin Index is < 1). The highest diversity and balance of the communities are characteristic for carnivorous fishes (Brachymystax lenok, Hucho taimen, Thymallus arcticus, Esox lucius, and Percafluviatilis). The component parasitic communities of Leuciscus leuciscus baicalensis, Rutilus rutilus, and Leocottus kesslerii are the most diverse in Lake Baikal since the Shennon index for L. leuciscus baicalensis, R. rutilus, and L. kesslerii is 2.4, for Paracotlus knerii--2.2, Limnocoitus godlewskii--2.3, Phoxinus phoxinus--2.1, Lota lota and Limnocuttus pallidus--1.9, P. fluviatilis--1.8, Leuciscus idus--1.8. The component parasitic communities of other fishes in Lake Baikal have low indices of biological diversity (H = 0.5-1.05, Smp is close to 1). A classification of mature and immature components of parasitic communities based on the ratio of specialist species and generalist species has been proposed. It is established that the component parasitic communities in sublitoral, profundal, and pseudoabyssal zones are mature, while in the littoral zone they are immature (impoverished and weakly balanced). The component parasitic communities in benthophagous fishes and predators are mature, in planktivorous fishes they are immature. The component parasitic communities are mature in the family Cyprinidae and immature in the families Coregonidae and Cottidae. The component parasitic communities of the Boreal Plain and Boreal Submountain faunal complexes are mature, but they are immature in Lake Baikal and Arctic freshwater complexes.     

Pollution and developmental abnormalities of Atlantic fishes

Synopsis Planktonic eggs of Atlantic mackerel,Scomber scombrus, provide evidence that pollution is associated with mortality, malformation, and abnormal chromosome division of fish embryos developing about the surface of the U.S. Atlantic coast. Embryo data are substantiated by the finding that adults of mackerel, windowpane flounder,Scophthalmus acquosus, and winter flounder,Pseudopleuronectes americanus, from more polluted coastal areas also have higher frequencies of mitotic abnormality than those from less polluted regions of the Mid- and North Atlantic. No ontogenetic interval escapes contamination. All are likely to be adversely influenced, resulting in considerable direct and indirect cumulative effect on total early-life survival. Development of genetic and epigenetic resistance to reproductively harmful influences of contaminants may interfere with other modifications in structure and function necessitated by natural environmental fluctuations, changes in climate, and by fishing itself.     

Two new anthiine fishes from the eastern tropical Atlantic

Two anthiine fishes from the eastern tropical Atlantic are described as newHolanthias cyprinoides andAnthias helenensis. The former is distinguished from the other Atlantic species ofHolanthias in having the forked caudal fin with rounded lobes and from the Indo-Pacific species in having no elongated dorsal spines or soft rays. The latter is closely related toAnthias asperilinguis Günther (South America, Atlantic coast), but differs from it in having more pectoral fin rays and more gill rakers. The present investigation onAnthias suggests that AtlanticAnthias is a genus distinct fromPseudanthias of the Indo-Pacific.     

New trematode genera from fishes of the southern Atlantic

Two new genera of the lepocreadiid trematodes, Gibsonia gen. n., (type species--G. hastata sp. n.) from Macrourus carinatus Günther, 1878 (Macrouridae), collected in the Falkland Islands area, and Muraenolepitrema gen. n. (type species--M. magnatestis sp. n.) from Muraenolepis microps L?nnberg, 1905 (Muraenolepidae), collected in the South Georgia Island area, are described. Gibsonia gen. n. differs from all known genera of the family Lepocreadiidae by unusual body shape divided into 2 parts, suctorial formations, great number of glandular cells and a muscular bulge of the body sides; it differs from the closely related genus Lepidapedon by separate genital pores. Muraenolepitrema gen. n. differs from Myzoxenus by bursa shape, separate genital pores, lobed shape of genital organs.     

Flabelliferan isopods (Crustacea) parasitic on freshwater fishes of Thailand

Two species of flabelliferan isopods are described based on specimens found in the gill cavities and/or body surfaces of 13 species of Thai inland fishes. They are: Alitropus typus Milne-Edwards, 1840 (Aegidae) from Belodontichthys dinema, Cirrhinus jullieni, Cyclocheilichthys enoplos, Cynoglossus microplepis, Hampala macrolepidota, Kryptopterus bleekeri, Mystus nemurus, Mystus wyckii, Pangasianodon gigas, Pangasius larnaudii, Puntius gonionotus and Wallagonia attu; and Corallana grandiventra n. sp. (Corallanidae) from Pangasianodon gigas and Tilapia nilogica. This report establishes the first true occurrence of Corallana in the inland water.     

Lernanthropid copepods (Siphonostomatoida) parasitic on fishes of the Gulf of Thailand

Five species of copepods (Siphonostomatoida: Lernanthropidae) parasitic on fishes of the Gulf of Thailand are reported. They are: Lernanthropus corniger Yamaguti, 1954 from Megalaspis cordyla (Linnaeus); L. latis Yamaguti, 1954 from Lates calcarifer (Bloch); L. nemipteri Jayasree & Pillai, 1976 from Scolopsis lineata Quoy et Gaimard; L. sillaginis Pillai, 1963 from Priacanthus tayenus Richardson; and Norion tayenus n. sp. from P. tayenus. Except for L. sillaginis, the remaining four species are new to Thailand. Lernanthropus priacanthi Kirtisinghe, 1956 is transferred to Norion as N. priacanthi (Kirtisinghe, 1956) n. comb.     

A key to the species of Acanthocephala parasitic in British freshwater fishes

We present methods for the collection, fixation, preservation and examination of the acanthocephalans parasitic in British freshwater fishes. An illustrated key to the species is provided.     

Gill monogeneans of the chub mackerel, Scomber japonicus from Madeiran waters of the Atlantic Ocean, Portugal

Five species of monogeneans were recovered from the gill filaments of 181 chub mackerel, Scomber japonicus, from the Madeiran waters of the Atlantic Ocean, Portugal, during 2004/2005. The monogenean Pseudokuhnia minor showed the highest prevalence (98.68%) and a mean intensity of 28.23, followed by Kuhnia scombri (prevalence of 43.71% and mean intensity of 2.69) and K. scombercolias (prevalence of 39.1% and a mean intensity of 1.81). Kuhnia sprostonae and Grubea cochlear were rare, occurring in only one and five fish hosts respectively. No correlation between fish host length and mean intensity of infection with the three most abundant monogeneans was found. However, significant differences in prevalence and abundance were found in relation to date of sampling for P. minor, and all parasites were aggregated in their distribution.     

A new genus of parasitic ciliata from tropical fishes

Ichthyophthirius schlotfeldti Yunchis, 1997 (Ophryoglenidae) was described by the junior author from aquarium fishes from South-East Asia. In the present paper this species is separated into a new genus Neoichthyophthirius gen. n. The reproduction of this species takes place within the epithelium of fishes and not in water as in Ichthyophthirius multifilius. Neoichthyophthirius schlotfeldti has a ring-shaped macronucleus with ends overlapping. Maximum temperature, when the reproduction is possible, is about +34 degrees. The parasite is pathogenous and causes a mortality of aquarium fishes.