Description of two new myxosporean species parasitic in freshwater fishes from the Yangtze River in China

Two new species of myxosporeans (Myxosporea: Myxidiidae), Myxidium tuanfengensis sp. n. and Zschokkella saurogobionis sp. n., Parasitic in freshwater fishes collected from the Yangtze River of China are described in this paper. M. tuanfengensis was found in the liver parenchyma and intestine lumen of Leptobotia taeniops Sauvage, 1878, while Z. saurogobionis was found in the gall bladder of Saurogobio dumerili Bleeker, 1871. The diagnostic characters of M. tuanfengensis are: round or elliptical polysporous plasmodia averaging 118 mum in size; spore oval in frontal view with smooth surface and nearly spindle-shape in sutural view with slightly sinuous sutural ridge, averaging 19.5 x 9.75 x 8.9 mum in size; two large spherical polar capsules 6.8 mum in diameter, with polar filament wound in 4 to 5 coils. The diagnostic characters of Z. saurogobionis are: spore elliptical in both frontal and sutural view measuring 18.3 x 9.8 x 10.8 mum in size; fine sutural ridge in S-form, spore shell marked with 10 to 12 distinct lines paralleled with the sutural line; two spherical polar capsules, 6.7 mum in diameter, with polar filament in 5 coils.

Observations on two species of phyllodistomes (Trematoda : Gorgoderidae) from fishes of the Hubei Province, central China, with an erection of Neophyllodistomum gen. n.

Two rare trematode species so far reported in the genus Phyllodistomum Braun, 1899, P. pawlovskii (Zmeev, 1936) and P. serrispatula Chin, 1963, were found in the urinary system the yellow catfish Pelteobagrus fulvidraco (Richardson) of Bao'an Lake (prevalence 8 %) and the swamp eel Monopterus albus (Zouiev) of Liangzi Lake (prevalence 6 9/6), respectively, from the Hubei Province, central China. In contrast to the original description, P. pawlovskii showed a considerable morphological variability particularly in the shape, size and topography of testes. A unique morphological feature of P. serrispatula is the presence of many conspicuous lateral outgrowths on the hindbody and, principally based on this character, a new genus Neophyl-lodistomum is erected (type species N. serrispatula (Chin, 1963) comb. n.)) to accommodate this species. Both trematode species are briefly redescribed. P. pawlovskii and N. serrispatula are reported for the first time from the Hubei Province and the former from the Yangtze River drainage system.

Mitochondrial d-loop sequence variation and phylogeny of gobiobotine fishes

The mitochondrial DNA control region is amplified and sequenced from 8 genera and 10 species of gobiobotine fishes. The phylogenetic tree of Gobiobotinae and some representative species of other Cyprinid subfamilies obtained by the method of neighborhood joining, maximum likelihood and maximum parsimony with Danio rerio as an outgroup indicates that Gobiobotinae fishes are a monophyletic group which is close to Gobioninae subfamily. Gobiobotinae should be included into subfamily Gobioninae in terms of phylogenetic analysis. The research result supports that Gobiobotinae can be divided into genus Xenophysogobio and Gobiobotia. Xenophysogabio is the most primitive genera in the subfamily.

Sequence variations of the S7 ribosomal protein gene in primitive cyprinid fishes: Implication on phylogenetic analysis

Cyprinidae is the largest fish family in the world and contains about 210 genera and 2010 species. Appropriate DNA markers must be selected for the phylogenetic analyses of Cyprinidae. In present study, the 1st intron of the S7 ribosomal protein (r-protein) gene is first used to examine the relationships among cyprinid fishes. The length of the 1st intron obtained by PCR amplification ranges from 655 to 859 by in the 16 cyprinid species investigated, and is 602 by in Myxocyprinus asiaticus. Out of the alignment of 925 nucleotide sites obtained, the parsimony informative sites are 499 and occupy 54% of the total sites. The results indicate that the 1st intron sequences of the S7 r-protein gene in cyprinids are rich in informative sites and vary remarkably in sequence divergence from 2.3% between close species to 66.6% between distant species. The bootstrap values of the interior nodes in the NJ (neighbor-joining) and MP (most-parsimony) trees based on the present S7 r-protein gene data are higher than those based on cytochrome b and the d-loop region respectively. Therefore, the 1st intron sequences of the S7 r-protein gene in cyprinids are sensitive enough for phylogenetic analyses, and the 1st intron is an appropriate genetic marker for the phylogenetic reconstruction of the taxa in different cyprinid subfamilies. However, attempts to discuss whether the present S7 r-protein gene data can be applied to the phylogeny of the taxa at the level of the family or the higher categories in Cypriniformes need further studies.

The uplift of Qinghai-Xizang (Tibet) Plateau and the vicariance speciation of glyptosternoid fishes (Siluriformes : Sisoridae)

Based on the phylogenetic and biogeographical studies of the glyptosternoid fishes in Qinghai-Tibet area, the following hypothesis is proposed: the speciation of this group has a direct relationship with the three uplift intervals of the Qinghai-Tibet Plateau. This process was explained by the theory of vicariance of biogeography. The ancestor of this group was similar to Bagarus and/or Glyptothorax, which still have a wide distribution. At the moment when the Tethys sea closed, the Indian tectonic plate collided with the Eurasian tectonic plate, so the Glyptothorax-like and Bagarus-like ancestors entered Eurasia and gradually became widely distributed. After the Pleistocene, with the enforced colliding, the gradual uplift of the Qinghai-Tibet Plateau brought about the current water environment, and the Glyptosternoids were generated from Glyptothorax-like fish under this environment. The present Glyptosternum, distributed across the Himalayas is the ancestor of Glyptosternoids. In the three uplift intervals of the plateau, the water system of this region was separated gradually and Glyptosternum-like ancestor was isolated in different rivers and evolved into various species. All this resulted in the speciation and formation of the biogeographical pattern of glyptosternoids.

A conserved family of doublesex-related genes from fishes

The sex-determining gene Mab-3 of C. elegans and the doublesex gene of Drosophila each contain a common DM domain and share a similar role. Human doublesex-related gene DMRT1 also encodes a conserved DM-related DNA-binding domain. We present here the amplification of a broad range of DM domain sequences from three fish species using degenerate PCR. Our results reveal unexpected complexity of the DM domain gene family in vertebrates. (C) 2002 Wiley-Liss, Inc.

Long-term changes of planktonic rotifers in a subtropical Chinese lake dominated by filter-feeding fishes

1. The long-term changes (1956-1998) in density and species composition of planktonic rotifers were studied at two sampling stations (I, II) of Lake Donghu, a shallow eutrophic Chinese Lake densely stocked with filter-feeding fishes. Annual average densities of rotifers increased with an increase in fish yield and eutrophication, whilst species number decreased from 82 in 1962-1963 to 62 in 1994-1998. 2. During 1962-98, some species such as Anuraeopsis fissa, Polyarthra spp. (including P. dolichoptera & P. vulgaris), Trichocerca pusilla and Synchaeta oblonga increased their percentage in abundance remarkably, whilst the proportion of Keratella cochlearis decreased at two relatively eutrophic stations from 19 to 4.2% at Station I and from 30 to 3.2% at Station IL 3. The high r(max) of A. fissa probably made it more successful than other rotifers under high predation pressure by planktivorous fish. The decrease in the K. cochlearis population might be attributed partly to predation by Cyclops vicinus. 4. Small rotifers were less vulnerable to fish predation than large-sized cladocerans. Decreases in cladocerans coincided with increases in rotifers, suggesting that the indirect effect of fish predation on cladocerans might have partly contributed to the population development of rotifers in Lake Donghu during recent decades. 5. We also conducted surveys (1994-1998) of seasonal dynamics of rotifers at four sampling stations (I-IV) which have varied in trophic status after fragmentation of the lake in the 1960s. A total of 75 species were identified at the four stations. Both densities and biomass of rotifers were considerably higher in the two more eutrophic stations than in the two less eutrophic stations. This indicates that the population increase of rotifers at Stations I and II during recent decades might be partly attributed to eutrophication of the lake water.

Dietary-morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. glurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal feud, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species. (C) 2001 The Fisheries Society of the British Isles.

Phylogeny of the specialized schizothoracine fishes (Teleostei : Cypriniformes : Cyprinidae)

Phylogeny of the specialized schizothoracine fishes (Teleostei: Cypriniformes: Cyprinidae). Zoological Studies 40(2). 147-157. To elucidate phylogenetic relationships within the specialized schizothoracine fishes, we used 41 variable osteological and external characters among this groups, three species of Schizothorax, and 1 fossil species. When the 3 species of Schizothorax were designated as an outgroup and all 41 characters were set as unordered with equal weighting, the data matrix yielded a single most-parsimonious tree with a tree length of 71 steps, a consistency index of 0.6761, and a retention index of 0.7416. Meanwhile, a bootstrap test was conducted to verify the reliability of the results. The matrix was also analyzed for different conditions: all characters were ordered and the fossil species was added as an outgroup. The phylogenetic analyses presented herein support the following hypotheses. 1) All species of the specialized schizo-thoracines fishes form a monophyletic group. 2) Monophyly of the genus Ptychobarbus is not supported by the bootstrap test or when these characters are ordered. 3) The genus Gymnodiptychus forms a monophyletic group. 4) All species of Ptychobarbus and Gymnodiptychus form a monophyletic group with Diptychus as its sister group.

Impacts of filter-feeding fishes on the long-term changes of crustacean zooplankton in a eutrophic subtropical Chinese lake

Long-term changes In the crustacean zooplankton community (calanoid and cyclopoid copepods and cladocerans) were studied in Lake Donghu, a shallow and eutrophic Chinese lake. This lake had been earlier stocked with two pump Alter-feeding Ashes, silver carp (Hypopthalmichthys molitrix) and bighead carp (Aristichthys nobilis). During the 1950s and the mid-1980s, the ratio of copepods to cladocerans was relatively stable but showed a general increase thereafter. From the early-1980s to the 1990s, calanoid/cyclopoid ratios decreased obviously. In the 1990s, Cyclops vicinus, Diaphanosoma brachyurum, and Moina micrura were dominant the abundance of C. vicinus and M. micrura increased significantly; and D, brachyurum showed a substantial decrease. The study shows that under extremely high pressure of Ash predation, the species which could recover rapidly from fish predation would be the most likely to survive and increase their numbers.

Freshwater fishes distribution in Taiwan and continent of China and its biogeographical significance

Through the comparative analysis of primary freshwater fishes in Chinese continent and the Taiwan Island, we summarize the three distinctions of distribution of freshwater fishes in these areas: (i) there exists a high similarity of freshwater fish fauna between Taiwan and the southeastern shore of the continent; (ii) some species of freshwater fish are found both in the Taiwan Island and East Himalayans; (iii) different freshwater fishes have different distributions in island arch of western Pacific where Taiwan is located, but the distribution pattern shows a similarity to that of adjacent continent. The characteristic distributions of the fishes are closely related to the change in paleogeography and geology in the area. The parsimony analysis of endemicity (PAE analysis) indicates that the three distribution patterns can be explained by the vicariance theory.

Sequences of cytochrome b gene for primitive cyprinid fishes in East Asia and their phylogenetic concerning

1140 bp of cytochrome b gene were amplified and sequenced from 14 species of primitive cyprinid fishes in East Asia. Aligned with other ten cytochrome b gene sequences of cyprinid fish from Europe and North America retrieved from Gene bank, we obtained a matrix of 24 DNA sequences. A cladogram was generated by the method of Maximum likelihood for the primitive cyprinid fishes. The result indicated that subfamily Leuciscinae and Danioninae do not form a monophyletic group. In the subfamily Danioninae, Opsariichthys biden and Zacco platypus are very primitive and form a natural group and located at the root. But the genera in subfamily Danioninae are included in different groups and have not direct relationship. Among them, Aphyocypris chinensis and Yaoshanicus arcus form a monophyletic group. Tanichthys albonubes and Gobiocypris rarus have a close relation to Gobioninae. The genus Danio is far from other genera in Danioninae, In our cladogram, the genera in Leuciscinae were divided into two groups that have no direct relationship. The genera in Leuciscinae distributed in Europe, Sibera and North America, including Leuciscus, Rutilus, Phoxinus, N. crysole, Opsopoeodus emilae, form a monophyletic group. And the Leuciscinae in southern China including Ctenopharyngodon idellus, Mylopharyngodon piceus, Squalibarbus and Ochetobius elongatus have a common origination.

Seasonal patterns in feeding ecology of three small fishes in the Biandantang Lake, China

Feeding ecology of three small fish species, Hypseleotris swinhonis, Ctenogobius giurinus and Pseudorasbora parva was studied seasonally in the Biandantang Lake, a small, shallow lake in central China. Gut length, adjusted for total body length, was significantly higher in spring than in other seasons for all the three species. Seasonal changes in gut length were not associated with changes in food quality. Weight of fore-gut contents, adjusted for body weight, was significantly higher in winter and spring than in summer and autumn in H. swinhonis and C. giurinus, and significantly higher in autumn than in spring and summer for P. parva. Percentage of empty fore-guts was highest in summer and lowest in spring for I-I. swinhonis and C. giurinus, and highest in winter and lowest in autumn for P. parva. Diet of the three small fishes showed apparent seasonal changes, and these changes reflected partly the seasonal fluctuations of food resources in environment. Diet breadth was high in winter and low in autumn for H. swinhonis, high in winter and low in spring and summer for C. giurinus, and high in autumn and low in spring for P. parva. Diet overlaps between pairs of species were biologically significant in most cases, except between H. swinhonis and P. parva in summer and autumn and between C. giurinus and P. parva in autumn. (C) 2000 The Fisheries Society of the British Isles.

Changes of Leptodora kindti abundance (1957-1996) in a planktivorous fishes-dominated subtropical Chinese lake (Lake Donghu)

The changes of L. kindti density from 1957 to 1996 were studied in a shallow, eutrophic Chinese lake, Lake Donghu. Despite the fact that the fish yield of planktivorous fish (silver carp and bighead carp) has increased steadily, the population density of L. kindti has also increased since 1957 and peaked in 1982/1983, The increase of both fish and L. kindti densities during this period may have benefitted from a considerable increase in the densities of their zooplankton prey. and fish predation on L. kindti might have been minor. As the fish yield increased further, their predation began to suppress most zooplankton prey including L. kindti. The largely increased fish predation on L. kindti is also evidenced by the remarkable decline of their body length after 1984. The density of L. kindti was significantly higher at the pelagic station (II) than at the littoral station (I), although for L. kindti, the littoral zone was significantly more resource profitable than the pelagic zone. The gradient of fish predation (more fish in the littoral zone) is the most likely explanation, since L. kindti is reported to be a preferred prey for many planktivorous fishes. The maximum density of L. kindti was 1.78 ind./I (on Aug. 17, 1984) at Station I and 1.55 ind./I (on Sep. 13, 1985) at Station II, respectively, which are close to those in several other eutrophic lakes.

Food consumption and growth of two piscivorous fishes, the mandarin fish and the Chinese snakehead

Rates of maximum food consumption and growth were determined for immature mandarin fish Siniperca chuatsi (47.2-540.2 g) and Chinese snakehead Channa argus (45.0-546.2 g) at 10, 15, 20, 25, 30 and 35 degrees C. The relationship between maximum rate of food consumption (C-max), body weight (W) and temperature (T) was described by the multiple regression equations: lnC(max) = -4.880 + 0.597 lnW+0.284T - 0.0048T(2) for the mandarin fish, and lnC(max)= -6.718 + 0.522 lnW+0.440T-0.0077T(2) for the Chinese snakehead. The optimum temperature for consumption was 29.6 degrees C for the mandarin fish and 28.6 degrees C for the Chinese snakehead. The relationship between growth rate (G), body weight and temperature was ln(G+0.25)= - 0.439 - 0.500 lnW+0.270T - 0.0046T(2) for the mandarin fish, and ln(G+0.25)= - 6.150+ (0.175 - 0.026T) lnW+0.571T - 0.0078T(2) for the Chinese snakehead. The weight exponent in the growth-weight relationship was -0.83 for the mandarin fish, but decreased with increasing temperature for the Chinese snakehead. The optimum temperature for growth was 29.3 degrees C for the mandarin fish, but tended to decrease with increasing weight for the Chinese snakehead, being 30.3 degrees C for a 45-g fish, and 26.1 degrees C for a 550-g fish. (C) 1998 The Fisheries Society of the British Isles.