Search

Estuaries provide a variety of habitat types for fishes, where abundant food resources and protection from predators have been identified as important drivers of the high abundance of species that use these areas as nursery grounds. However, scientific consensus regarding the role of some habitats as nurseries remains limited. Here, we analyzed the trophic ecology of four juvenile fish species (Atherinella brasiliensis, Anchoa hepsetus, Rhinosardinia bahiensis, and Diapterus rhombeus) that occupy three habitats in a tropical estuary (mangrove fringes, seagrass beds, and mudflats), using samples collected during rainy and dry seasons. The aim of the present study was to investigate whether variations in the diet composition of juvenile fishes were mediated by changes in zooplankton prey availability in these estuarine habitats during the seasonal cycle (rainy/dry). The fish and zooplankton prey were caught at the same time. The analysis suggested that changes in the abundance of zooplankton prey items in estuarine habitats and seasons may have significant effects on fish diet. However, complex habitat structure did not drive predator-prey relationships. Mudflats are the main foraging sites for juvenile fishes in this tropical estuary, while fringe mangrove showed a weak influence on the abundance and diet of juvenile filter-feeders (R. bahiensis and A. hepsetus). The juvenile fish species were dependent on multiple habitats, and no species used only one habitat type exclusively. Understanding the dynamics of prey resources in different estuarine habitats is critical for their conservation, especially in those habitats that are uncommonly considered, such as mudflats.

In this study, morphological differences were found that corroborate earlier results that showed the existence of six species within the previously monospecific African pike genus Hepsetus. Additional genetic data (coI, mtDNA and rag1, nDNA) confirm the morphology-based species delineations. Deep genetic divergences imply a relatively old age for diversification within the genus. An identification key for the six species is provided in the present study.

Changes made to the scientific names of southern African freshwater fishes since 2001 are explained and discussed. Adjustments to the phylogeny and classification of the fauna are outlined. Recent systematic studies on cyprinines are discussed and changes to the genera Labeobarbus (expanded concept), Pseudobarbus (expanded concept), and Enteromius are supported. The introduction of the family names Alestidae and Nothobranchiidae is discussed. Adjustments made to the genera Nannocharax, Micropanchax, Tilapia, Coptodon and Mastacembelus are explained. Species name changes for Hepsetus and Zaireichthys are detailed. New species described from the region, or resurrected from synonymy, since 2001 are listed.

In the Upper Zambezi and Okavango ecoregions, Brycinus lateralis, Hepsetus cuvieri, Schilbe intermedius and Serranochromis macrocephalus are important in subsistence fisheries, while S. intermedius and S. macrocephalus are often caught in commercial catches. Despite their importance, there is little information on their age and growth and age validation. Growth zone deposition rate in otoliths of B. lateralis, H. cuvieri, S. intermedius and S. macrocephalus was validated as annual using edge analysis in this study. Annual deposition of growth zones was corroborated by a fluorochrome marking experiment. Both methods demonstrated that one growth zone was deposited annually. Edge analysis demonstrated that the highest proportion of opaque zones was detected between August and December, most likely as a result of slow growth during lower temperature water during the preceding winter. With growth zone deposition validated as annual, future research should focus on determining the growth, maturity and mortality...

Атерины (сем. Atherinidae) — массовые представители прибрежной пелагической ихтиофауны Азово-Черноморского бассейна, в некоторых районах являются объектами промысла. Вместе с тем сведения о биологии и экологии атерин до настоящего времени остаются крайне скудными и фрагментарными. Данная работа посвящена изучению меж- и внутригодовой (сезонной) изменчивости ряда индивидуальных и популяционных репродуктивных показателей атлантической атерины Atherina hepsetus из акватории Черного моря, прилегающей к западному побережью Крыма. Отлов производился ставными неводами круглогодично в течение 2010–2014 гг. с периодичностью 2–3 раза в месяц. В общей сложности изучено 2403 экз. На основе результатов исследования впервые введены понятия общего, популяционного и массового (пик нереста) репродуктивных периодов, установлены межгодовые изменения их продолжительности, а также календарные сроки начала и окончания. Изучены интенсивность нереста и его сезонная динамика, сезонная динамика развития половых желез самцов и самок и определены индивидуальные и среднепопуляционные значения их гонадосоматического индекса. Установлен диапазон изменчивости температуры нереста (8.5–14.5 ℃), выделена зона максимально благоприятной нерестовой температуры (9.0–12.0℃).

Members of the genus Kudoa are typically histozoic and only a few are coelozoic parasites, mainly in marine fishes. In the present study, 2 novel Kudoa species were recovered and described as Kudoa niluferi sp. nov. in the musculature of Neogobius melanostomus and Kudoa anatolica sp. nov. in the musculature, urinary bladder and kidney of Atherina hepsetus collected from the coast of Sinop on the Black Sea. Means ± SD (ranges) of mature spores of K. niluferi sp. nov. were 5.9 ± 0.1 (5.7-6.1) µm in length, 9.2 ± 0.2 (8.8-9.5) µm in width and 7.5 ± 0.3 (7.0-8.1) µm in thickness, while those of K. anatolica sp. nov. were 4.1 ± 0.3 (3.5-4.1) µm in length, 7.1 ± 0.2 (6.7-7.2) µm in width and 5.7 ± 0.2 (5.3-6.0) µm in thickness. In both parasite species, length and width of the 4 polar capsules were not equal and formed 3 distinct size classes, largest (1), intermediate (2) and smallest (1) in size. The prevalence and intensity of infection by K. niluferi sp. nov. were 12.8% and 20-29 parasites (per field-of-view, at 200× magnification), respectively, in the musculature of N. melanostomus. These values for K. anatolica sp. nov. were 32.1% and 10-19 parasites in the musculature as well as 2.9% and 20-29 parasites jointly in the kidney and urinary bladder of A. hepsetus. Phylogenetic analysis based on nuclear small subunit rDNA also suggested K. niluferi and K. anatolica as 2 novel species. These species appeared in the same lineage with K. nova and formed a Black Sea lineage.

This study was carried out to investigate some physico chemical parameters and also to examine Nickel Lead Manganese and Copper from Gill liver and fillet of three selected fin fish species Oreochromis niloticus Synodontis clarias and Hepsetus odoeof the lake to provide information on the human consumption safeties of these fish samples from the lake Surface water and fish samples from three stations and fisherman landing site respectively were collected bi monthly for three months Surface water temperature pH and Dissolved Oxygen were measured in situ while other parameterswere determined according to APHA standard methods Data were analyzed using descriptive statistics ANOVA and Duncan Multiple Range Test DMRT at alpha All the measured physico chemical parameters are within the recommended permissible limit for aquaculture Copper recorded the highest metal concentration mu g g in the gill of Oreochromis niloticus Nickel was not detected in all the observed fish species The mean concentrations of all the metals in the present study were lower than the permissible limits thus the sampled fish from the lake are generally safe for human consumption

Made available in DSpace on 2018-11-26T17:42:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-12 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Hepsetidae is a small fish family with only the genus Hepsetus, with six described species distributed throughout the South, Central and Western regions of Africa, showing a close relationship with the Alestidae and some Neotropical fish families. However, no cytogenetic information is available for both Hepsetidae and Alestidae species, thus preventing any evolutionary comparative studies at the chromosomal level. In the present study, we are providing new cytogenetic data for Hepsetus odoe, including the standard karyotype, C-banding, repetitive DNAs mapping, comparative genomic hybridization (CGH) and whole chromosome painting (WCP), providing chromosomal patterns and subsidies for comparative cytogenetics with other characiform families. Both males and females H. odoe have 2n = 58 chromosomes (10m + 28sm + 20st/a), with most of the C-band positive heterochromatin localized in the centromeric and subtelomeric regions. Only one pair of chromosomes bears proximal 5S rDNA sites in the short arms, contrasting with the 18S rDNA sequences which are located in the terminal regions of four chromosome pairs. Clear interstitial hybridization signals are evidenced for the U1 and U2 snDNA probes, but in only one and two chromosome pairs, respectively. Microsatellite motifs are widely distributed in the karyotype, with exception for the (CGG)(10), (GAA)(10) and (GAG)(10) probes, which highlight conspicuous interstitial signals on an unique pair of chromosomes. Comparative data from conventional and molecular cytogenetics, including CGH and WCP experiments, indicate that H. odoe and some Erythrinidae species, particularly Erythrinus erythrinus, share similar chromosomal sequences suggesting some relatedness among them, although bearing genomic specificities in view of their divergent evolutionary histories. Univ Fed Sao Carlos, Dept Genet & Evolucao, Sao Carlos, SP, Brazil Estado Educ Mato Grosso Seduc MT, Cuiaba, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil Royal Museum Cent Africa, Sect Vertebrates Ichthyol, Tervuren, Belgium Adamawa State Univ, Dept Fisheries & Aquaculture, Mubi, Nigeria Univ Hosp Jena, Inst Human Genet, Jena, Germany Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil CNPq: 304992/2015-1 CNPq: 401575/2016-0 FAPESP: 2016/21411-7 FAPESP: 2016/17556-0 FAPESP: 2017/08471-3 FAPESP: FAPESP 2014/26508-3 FAPESP: CNPq 306054/2006-0

An α-taxonomic revision of the African pike, Hepsetus odoe, from Lower Guinea is provided. The results show that three different species occur in Lower Guinea instead of one. Hepsetus akawo, recently described from West Africa, is present in the northern part of Lower Guinea; Hepsetus lineata, the most widespread species within Lower Guinea, is known from the Sanaga (Cameroon) in the north to the Shiloango (Democratic Republic of the Congo) in the south and Hepsetus kingsleyae sp. nov. is endemic to the Ogowe Basin. The new species H. kingsleyae is described and H. lineata, which is elevated here to the species level, is redescribed. Hepsetus lineata can easily be recognized by its prominent horizontal line pattern on the flanks and differs further from H. akawo and H. kingsleyae in the number of lateral-line scales and the number of gill rakers. Hepsetus kingsleyae differs from H. lineata and H. akawo by its narrow head, elongated snout and narrow, knife-shaped body. All three species are also distinguishable from H. odoe and the recently revalidated H. cuvieri. A few exceptional specimens could not be allocated to one of the three species and may represent hybrids because of their mixed diagnostic characters or their intermediate values.

We determined in this study the habitat preferences of seven native fish species in a regulated river in Southeastern Brazil. We tested the hypothesis that fishes differ in habitat preference and that they use stretches of the river differing in hydraulic characteristics and substrate type. We surveyed fishes in four 1-km long river stretches encompassing different habitat traits, where we also measured water depth, velocity, and substrate type. We investigated preference patterns of four Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus, and Trachelyopterus striatulus) and three Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus, and Hoplias malabaricus), representing approximately 70% of the total number of fishes and 64% of the total biomass. We classified fishes into four habitat guilds: (1) a slow-flowing water guild that occupied mud-sand substrate, composed of two Siluriformes in either shallow (< 4 m, i.e., H. littorale) or deep (> 8 m, L. castaneus) waters; (2) a run-dwelling guild that occurs in deep backwaters with clay-mud substrate, composed of the Characiformes A. aff. bimaculatus and O. hepsetus; (3) a run-dwelling guild that occurs in sandy and shallow substrate, composed of T. striatulus; and (4) a fast-flowing guild that occurs primarily along shorelines with shallow mud bottoms, composed of H. malabaricus and P. maculatus. Our hypothesis was confirmed, as different habitat preferences by fishes appear to occur in this regulated river. Determinamos neste estudo a preferência de habitat de sete espécies de peixes abundantes em um rio regulado do Sudeste do Brasil. Testamos a hipótese de que peixes diferem na preferência de habitat e usam trechos do rio com diferentes características hidráulicas e tipos de substratos. Realizamos amostragens de peixes, utilizando redes de espera e tarrafas em quatro trechos do rio de 1 km de extensão, compreendendo diferentes características do habitat, onde também obtivemos medidas de profundidade, velocidade da água e tipo de substrato. Quatro Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus e Trachelyopterus striatulus) e três Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus e Hoplias malabaricus) que juntos compreenderam aproximadamente 70% do número total e 64% do peso total de peixes foram estudados. Classificamos os peixes em quatro guildas: (1) peixes que ocorrem em trechos com baixa velocidade de fluxo e substrato constituído predominantemente de lama e areia, compreendendo dois Siluriformes, um de áreas rasas (< 4 m, i.e., H. littorale) e outro de áreas profundas (> 8 m, i.e., L. castaneus); (2) peixes que utilizam rápidos de áreas laterais mais profundas com substrato lamoso, representados pelos pequenos Characiformes, A. aff. bimaculatus e O. hepsetus; (3) peixes que utilizam rápidos que ocorrem em áreas rasas e substrato arenoso, representado por T. striatulus; e (4) peixes de corredeiras que utilizam as margens rasas com fundo lamoso, representados por H. malabaricus e P. maculatus. As espécies estudadas apresentam diferenciação na preferência por variáveis do hábitat, corroborando a hipótese investigada.

Pueblo Viejo Lagoon is an estuary with restricted communication with the sea, so the freshwater influence tends to be more important. Therefore, the study focused on testing the hypothesis that the seasonal changes in species abundance would be mainly related to the local rainfall pattern. Monthly samplings were carried out over a one-year, using a seine net. A total of 9108 individuals were caught, corresponding to 66 species of fish, most of them with marine origin. Canonical correspondence analysis revealed that the rainfall-salinity gradient was revealed to be the most important driving force in the seasonal variation of fish composition. In this way, it was observed that seasonal fluctuations in total fish number were linked to preceding fluctuations (one month) in local rainfall. Similar pattern was exhibited by the abundance of Anchoa mitchilli (the most abundant species), Oreochromis mossambicus and Ariopsis felis, and this delayed effect was significant (cross-correlation analyses). In addition, the rainfall showed a direct influence (significant positive correlations) on abundance of D. auratus and M. martinica. The association between fish number and the rainfall regime seems to be related to lagoon productivity and the trophic responses of these species. By contrast, Brevoortia gunteri and Menidia beryllina showed an inverse correlation with rainfall. Other environmental variables (also influenced by rainfall regime) showed a significant relationship with A. hepsetus (salinity), B. chrysoura (depth) and M. curema (turbidity). Thus, at least 12 species showed some relationship with local rainfall, which accounted for 81.27% of the total number of fish collected. Although it is difficult to separate the relative importance of physiological tolerances and biological functions such as trophic responses, the results suggest that rainfall is a primary factor governing seasonal variation in fish species abundance of Pueblo Viejo lagoon.

Within the genus Hepsetus, a new species from the eastern part of West Africa is described. Hepsetus akawo sp. nov. is mainly distinguished from Hepsetus odoe by a smaller number of lateral line scales [43–51 vs 50–60 (exceptionally 49)] and a shallower head depth [38.0–45.6 (mean 42.0) % head length vs 41.4–49.0 (44.6) % head length] (positively allometric). Hepsetus akawo sp. nov. differs mainly from the recently rehabilitated Hepsetus cuvieri by: a higher number of gill rakers (17–23 vs 8–13); and a lower number of scales between the dorsal fin and the lateral line (7½–9½ vs 10½–11½). Within West Africa, the distribution area of the new species is restricted to the Sassandra River (Ivory Coast) in the west up to the Cross River (Cameroon) in the east. The species is entirely allopatric with H. odoe, which has a far more restricted distribution than previously thought and occurs from the Senegal River (Senegal) in the west to the Cavally River (Ivory Coast) in the east.

A dramatic decline has been recorded in Croatian shellfish production in recent years. Among the many factors that may have contributed to the decline of mussel production, i.e. EU import barriers and consequently small domestic market, great variability in larval dispersion and settlement, it is suspected that fish predation plays an important role in shellfish sustainability. Following this hypothesis, the abundance and diversity of fish assemblages around the Marina mussel farm, situated along the eastern coast of the Adriatic Sea, was monitored for a two-year period, and the mussel recruitment losses, potentially driven from fish predation, after the ‘early thinning-out’ process was quantitatively evaluated by measuring the percentage of consumed or destroyed ropes of longlines. Overall, a total of sixteen fish taxa were recorded at the mussel farm, as opposed to fifteen taxa registered at all control locations. The asymmetrical design of the multivariate analyses revealed a statistically significant impact of the farm on fish assemblages, with expressed seasonal species variation. At mussel farm, the most abundant species observed were gilthead seabream Sparus aurata, sand smelt Atherina hepsetus and mullet Mugilidae species in summer and autumn; sand smelt A. hepsetus and bogue Boops boops in winter; and the sand smelt A. hepsetus, mullet Mugilidae species and seddled bream Oblada melanura in spring. At control locations, characterised with significantly lower fish assemblage abundances, the most abundant species were sand smelt A. hepsetus and mullet Mugilidae species in summer, sand smelt A. hepsetus and seddled bream O. melanura in autumn, sand smelt A. hepsetus and picarel Spicara flexuosa in winter, sand smelt A. hepsetus and bogue B. boops in spring. Gilthead sea bream was extremely abundant at mussel farm, with 5936 individuals censused in 155 of 192 fish counts (80%), and a maximum abundance of 285 individuals per 5000 m3. Stomach content analysis confirmed the presence of mussel Mytilus galloprovincialis as the dominant prey. During August (2009), monitoring of 423 ropes revealed that 276 m of mussel ropes or approximately 828 kg of mussels with an average shell length of 34.3 ± 2.54 mm were destroyed within the first week of mussel deposition into the sea. The recorded recruitment losses of 54% in only one month of monitoring indicate a strong negative impact on farm management stability.

The order Characiformes (Teleostei: Otophysi) is one of the most diverse freshwater fish groups. It contains around 1400 living species in South and Central America and Africa. Their fossil record starts in the Cretaceous on both continents and also in Europe. Here, we describe and discuss the occurrences of new characiform fish teeth from Provence (Maastrichtian, S. France). Five morphological types are recognized. They belong to possibly three different taxa, and they are regarded as Characiformes indet. However, two of them have resemblances to alestin fishes and could be related to the African family Alestidae. The characiform fishes from Provence are among the oldest known in Europe, together with a freshwater characiform fish occurring in Romania, and the recently described marine fish Sorbinicharax from Italy. The biogeographical history of characiform fishes has been intensively discussed during the last three decades. The group is generally accepted to be Gondwanan and its diversification linked with the break-up of this continent, with two main scenarios depending on whether the group is archaeoor telolimnic. Some authors also propose a Pangaean origin. The recent discoveries of Sorbinicharax and of the fossils from Provence change our view on the Cretaceous characiform diversity and their early ecology, and they also enable us to re-evaluate the proposed biogeographical scenarios, reinforcing the hypothesis of the telolimny of the group. The order Characiformes (Teleostei: Otophysi) includes the well-known tetras and piranhas. It contains around 1400 living species. About 1200 are South and Central American, the rest are African. Research over the last decade has hardly improved our knowledge of their intrarelationships; but many nodes of their phylogenetic tree are still debated and the monophyly of the order Characiformes itself is contested by some authors. For example, Peng et al. (2006) suggest that the order Gymnotiformes nests within the order Characiformes on the basis of molecular data. However, most specialists now agree about the monophyly of several taxa within the order, notably the four African families, i.e. Distichodontidae and Citharinidae which are also considered to be sister-groups (Vari 1979; Fink & Fink 1981; Orti & Meyer 1997), Hepsetidae (monogeneric with Hepsetus), and Alestidae (Paugy 1986, 1990; Murray & Stewart 2002; Zanata & Vari 2005). The family Alestidae corresponds to the African members of the nonmonophyletic Characidae sensu Greenwood et al. (1966), the polyphyly of which is now widely accepted (e.g. Buckup 1998; Lucena & Menezes 1998; Toledo-Piza 2000; Zanata & Vari 2005). The family Characidae as currently defined includes only American fishes. Whether they are based on morphological (Vari 1979, 1995; Buckup 1998) or DNA studies (Orti & Meyer 1997; Calcagnotto et al. 2005), the various phylogenetic analyses agree about the sister relationship of African and South American taxa in three cases and also about the fact that, of the transatlantic groups they form, one sits at the stem of the tree of the order and the two others at its crown. (1) Distichodontidae þ Citharinidae (African) is the sister group of all the other characiform fishes (with basal South American members), except for Uj (1990) who proposed a sister relation with the family Alestidae, thus forming with Erythrinidae, Hepsetidae and Ctenoluciidae the sister group of all the other characiform fishes. (2) The families Hepsetidae (African) and Erythrinidae (South American) form a monophyletic group either alone (Uj 1990; Orti & Meyer 1997), or including other families, i.e. Ctenoluciidae (Vari 1979; Buckup 1998), Ctenoluciidae and Lebiasinidae (Calcagnotto et al. 2005). Roberts (1972) remarks that among characiforms, only hepsetids and erythrinids From: CAVIN, L., LONGBOTTOM, A. & RICHTER, M. (eds) Fishes and the Break-up of Pangaea. Geological Society, London, Special Publications, 295, 155–164. DOI: 10.1144/SP295.10 0305-8719/08/$15.00 # The Geological Society of London 2008. are ambush predators with the particular behaviour of nest building and parental care. (3) The family Alestidae (African) is the sister-group of Acestrorhynchus and forms a monophyletic group with Ctenoluciidae and Brycon þ Salminus according to Orti & Meyer (1997) and to Calcagnotto et al. (2005), whereas it is the sister group of Brycon þ Chalceus according to Lucena (1993), and of Brycon and many others including Acestrorhynchus, Hepsetidae and Erythrinidae according to Buckup (1998). Uj (1990) only proposed a sister relation with the African monophyletic group Distichodontidae þ Citharinidae. Because of the Afro-South American distribution of living characiform fishes and the age of the fossils, a Gondwanan origin of the order is usually accepted (see also discussion). Depending on the ability of early members to stand salty waters, two different palaeobiogeographical scenarios have been proposed. That living characiform fishes are strictly freshwater fishes can be interpreted as reflecting the archaeolimny of the group (the archaeoand telolimny were defined by Patterson in 1975, according to primarily or secondarily fresh water habitat). This implies a vicariant scenario for the characiform fish historical biogeography. This hypothesis was first proposed by Lundberg (1993), who stressed two main points: (1) the diversification of the main taxa in the order Characiformes might have taken place on Gondwana before its break-up; and (2) early African characiform fishes would have to have suffered great extinctions in order to explain the lack of the many sister-groups of the South American families on this continent. A vicariant interpretation could also involve a primary break-up of Gondwana with possible temporary secondary connections between the lands formed, rather than just a unique break-up event. This would allow a better explanation of the differences between the American and African diversity and also the existence of three trans-Atlantic groups, due to three vicariant events (Patterson 1984; Fink et al. 1984; Maisey 1993, 2000; Lundberg et al. 1998). However, a second interpretative scenario takes shape if the order is telolimnic. The hypothesis of the telolimny of the group is supported by the brackish or marine habitat of several basal otophysan fishes and a few extinct characiform fishes: Lusitanichthys and Salminops (Cenomanian, Portugal), which are considered to be basal characiform fishes (Gayet 1981, 1985) or basal ostariophysan fishes possibly at the stem of the Otophysi (e.g. Fink & Fink 1981; Fink et al. 1984; Patterson 1993); Chanoides (Campano-Maastrichtian and Eocene, Italy), which is a primitive otophysan fish (Patterson 1984; Taverne 2005); Santanichthys (Aptian, Brazil), which is the earliest otophysan fish known yet, and should possibly be placed at the stem of the order Characiformes (Filleul & Maisey 2004); Sorbinicharax (CampanoMaastrichtian, Italy), which is a characiform fish recently described from marine Tethyan waters (Taverne 2003); and some Eocene and Oligocene characiform fossils from France that are described from brackish environments (Cappetta et al. 1972; Gaudant 1980). Moreover, many gonorynchiform fishes and the representatives of two siluriform families inhabit coastal marine waters or brackish waters: the Plotosidae and the Ariidae to which are related some of the oldest catfish fossils. In the opinion of some authors (e.g. Chardon 1967; Gayet 1982, 1986), this reflects the telolimny of the order Characiformes (among others), and supports the hypothesis of marine dispersal between the newly separated continents of the fragmented Gondwana. Based on the same evidence, Calcagnotto et al. (2005) also call on a probable early ability of characiform fishes to withstand salty waters, to build an alternate palaeobiogeographical scenario to the vicariance with possible migration from one plate to another. They note that this scenario could appear to be relatively more parsimonious, contra Patterson (1984), Fink et al. (1984), and Filleul & Maisey (2004), among others. Here, we describe and discuss the attribution of new characiform fishes from Provence (Maastrichtian, Southern France). They are among the oldest known, notably in Europe, together with the Campano-Maastrichtian marine fish Sorbinicharax from Italy (Taverne 2003), and a freshwater Maastrichtian characiform fish reported from Romania (Grigorescu et al. 1985). For a long time, the Romanian occurrence was the only one known north of the Tethys Sea for the Cretaceous, and it was logically interpreted as resulting from the trans-Tethyan dispersal(s) that affected vertebrate continental faunas during the Late Cretaceous (e.g. Gheerbrant & Rage 2006). Geological context and age The characiform teeth were collected by one of us (X.V.) from two new localities of the Provence Basin: Verane and Les Pennes-Mirabeau (Fig. 1). The fossiliferous deposits are composed of marly horizons with carbonate rich palaeosols (nodules and root traces). They are located just above the Rognac Limestone (dated as Maastrichtian by Garcia & Vianey-Liaud 2001). The material has been obtained by screen-washing the deposits. O. OTERO ET AL. 156

The genetic divergence and the phylogenetic relationships of six Atherina boyeri (freshwater and marine origin) and five Atherina hepsetus populations from Greece were investigated using partial sequence analysis of 12s rRNA, 16s rRNA and control region mtDNA segments. Three different well divergent groups were revealed; the first one includes A. boyeri populations living in the sea, the second includes A. boyeri populations living in the lakes and lagoons whereas the third one includes all A. hepsetus populations. Fifty-seven different haplotypes were detected among the populations studied. In all three mtDNA segments examined, sequence analysis revealed the existence of fixed haplotypic differences discriminating A. boyeri populations inhabiting the lagoon and the lakes from both the coastal A. boyeri and the A. hepsetus populations. The genetic divergence values estimated between coastal (marine) A. boyeri populations and those living in the lagoon and the lakes are of the same order of magnitude as those observed among coastal A. boyeri and A. hepsetus populations. The results obtained by different phylogenetic methods were identical. The deep sequence divergence with the fixed different haplotypes observed suggests the occurrence of a cryptic or sibling species within A. boyeri complex. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 151–161.

Data on the length-weight relationship, age, growth, sex ratio and mortality were analysed for the Mediterranean sand smelt, Atherina (Atherina) hepsetus L. (total = 2805 ; males = 1258 ; females = 1547) collected in the eastern middle Adriatic island area during the reproductive period (February to April) in 2002. The total length of sampled specimens ranged from 3.8 to 14.5 cm and the weight from 0.28 to 22.39 g. The overall sex ratio was 1.23 : 1 in favour of females, significantly different from the expected 1 : 1 ratio (χ 2 = 29.76 ; P < 0.05). All individuals >13.4 cm were females. The oldest collected male and female specimens were 5 years old. The von Bertalanffy growth formula was estimated for females (L = 15.79 (1-e0.43(t+0.049)) and males (L = 15.25 (1-e0.43(t+0.018)). The power values (b) of the length-weight relationship were very similar for both sexes (b = 3.14) and indicated a slightly allometric growth. The instantaneous rates of mortality for all collected fish were Z = 1.44 year1 ; M = 0.94 year1 and F = 0.50 year1. The exploitation ratio was E = F/Z = 0.35. The value for M is highly uncertain, however, as well as those values for F and E.

The pelagic (i.e. fishes that spend most of their time swimming and feeding in the water column) fish assemblage was examined within a temperate estuary to determine the seasonal patterns of abundance, biomass, richness, and species composition. These measures were related to abiotic measures including temperature, salinity, water transparency, and depth. Pelagic fish (n 000) were sampled weekly from August 1995 through December 1996 in Great Bay in New Jersey, USA, with a pop net (5 m diameter, 5 m length, 3 mm cod end). The most frequently occurring and abundant species included Clupea harengus (frequency of occurrence, 27.4%; abundance, 80.5% of total catch), Menidia menidia (frequency of occurrence, 83.5%; abundance, 10.6% of total catch), Anchoa mitchilli (frequency of occurrence, 66.5%; abundance, 6.0% of total catch), and Anchoa hepsetus (frequency of occurrence, 23.1%; abundance, 1.9% of total catch). There were strong seasonal trends in species richness, total abundance, and total biomass with peaks in spring, summer, and autumn, and very low values for these parameters in winter. In addition, there were five seasonal groupings within this pelagic fish assemblage that were primarily, but not exclusively, represented by young-of-the-year (age 0+). Winter (December–March) was represented by adult Gasterosteus aculeatus and age 1+ by M. menidia . Spring (April–early June) was overwhelmingly dominated by age 0+ C. harengus . Early summer (late June–early July) was relatively species rich and characterized by age 0+ of Brevoortia tyrannus , Pomatomus saltatrix , Alosa pseudoharengus , and age 1+ of A. mitchilli . Late summer (late July–August) remained relatively species rich and included mostly age 0+ of A. mitchilli , A. hepsetus , and M. menidia . Autumn (September–November) continued to have high catches of age 0+ of M. menidia and A. mitchilli . As expected for temperate estuaries, the best of the measured abiotic predictors of these groupings included temperature, salinity, and degree of change in temperature. However, timing of life history characteristics, such as location, and timing of reproduction and migration also influenced the seasonal occurrence of these pelagic species. The large abundance and biomass of a relatively few species, as observed in this study, are typical of estuaries, although this is one of the few studies that have focused solely on the pelagic component of estuarine fish assemblages.

In Florida, issues related to alterations of estuarine salinity caused by freshwater withdrawal have recently gained increasing attention. We examined nekton community structure in the Suwannee River estuary (1997–2000) and investigated the relationship between environmental factors and the abundance of fisheries resources. We compared nekton community structure and environmental factors seasonally and annually using multidimensional scaling (MDS) ordination and cluster analysis and observed a strong seasonal pattern. This pattern was consistent among years and closely paralleled those for temperature and river discharge. Representative species for cold seasons includedLeiostomus xanthurus andLagodon rhomboides, and those for warm seasons includedMembras martinica andAnchoa hepsetus. Species that contributed most to the dissimilarity in community structures between wet and dry seasons were abundant and generally preferred lower salinity (e.g.,L. xanthurus, Eucinostomus spp., andMenidia spp.). A period of low freshwater inflow during the latter portion of our study coincided with both decreases and increases in the abundances of some dominant and some economically important species. We have established a baseline which will assist in measuring the effects of long-term changes in freshwater input on the nekton communities of the Suwannee River estuary, but our ability to predict these effects is still limited.

The ichthyofaunas of Thaytiniti and Taqah (Lower Oligocene, Sultanate of Oman) and As-Sarrar (Burdigalian, Saudi Arabia) are studied with particular emphasis on palaeoenvironmental and palaeobiogeographic approaches. The fossil fish reported from these sites include freshwater and marine taxa: Osteoglossiformes Osteoglossidae ( Heterotis sp.); Cypriniformes Cyprinidae (? Barbus sp. ); Characiformes Hepsetidae ( Hepsetus sp.); Characidae Alestinae (two types); Siluriformes Bagridae ( Bagrus sp.), Clariidae [Clariidae indet., Clarias ( Clarias )], Mochokidae ( Synodontis sp.); Perciformes Latidae [ Lates ( Lates ) sp. cf. Miloticus , L. niloticus ]; Sparidae (four morphotypes); Tetraodontiformes Tetraodontidae (Tetraodontidae indet.) and Diodontidae (Diodontidae indet.). Study of the habitat of the Recent taxa and fossil relatives, nature of preservation, biotic associations and sedimentological features are integrated to ascertain palaeoenvironmental scenarios. An analysis of the ecology of the ichthyofauna and its evolution since the Oligocene is studied in relation with the African ichthyofaunas. The palaeobiogeographical study focuses on the exchanges and direction of migrations of freshwater fish between Asia and Africa at the time of the Early Miocene terrestrial connection between the two continents.

The aim of this study was to assess the ecomorphological patterns and diet of four Characiformes fish species in a poorly physically structured tropical reservoir. We tested the hypothesis that body shape and diet are associated, because environmental pressure acts on the phenotype, selecting traits according to the available resources. Ten ecomorphological attributes of 45 individuals of each species - Astyanax cf. bimaculatus (Linnaeus, 1758), Astyanax parahybae Eigenmann, 1908, Oligosarcus hepsetus (Cuvier, 1829), and Metynnis maculatus (Kner, 1858) - , collected between February and November 2003, were analyzed, and the patterns were assessed using Principal Components Analysis (PCA). Diet similarity among fish species was assessed using cluster analysis on feeding index. The first two axes from PCA explained 61.73% of the total variance, with the first axis being positively correlated with the compression index and relative height, whereas the second axis was positively correlated with the pectoral fin aspect. Two well-defined trophic groups, one herbivorous/specialist (M. maculatus) and the other formed by two omnivorous/generalist (A. cf. bimaculatus, A. parahybae) and one insectivorous-piscivorous (O. hepsetus) were revealed by the cluster analysis. Astyanax. cf. bimaculatus and A. parahybae differed. The first has comparatively greater relative height, relative length of the caudal peduncle and lower caudal peduncle compression index. However, we did not detect a close correspondence between diet and body shape in the reservoir, and inferred that the ecomorphological hypothesis of a close relationship between body shape and diet in altered systems could be not effective.

To describe the histology of the digestive tract and to investigate the occurrence of endocrine cells in Oligosarcus hepsetus (O. hepsetus).The digestive tract (DT) of O. hepsetus was divided into esophagus, two stomach regions (glandular and non-glandular) and two intestinal regions (anterior and posterior). These specimens were processed by routine histological techniques and stained with hematoxylin-eosin, Gomori's trichrome, periodic acid Schiff (PAS) and Alcian blue (AB). An immunohistochemical method using avidin-biotin-peroxidase was employed.The esophagus is lined with a non-keratinized stratified squamous epithelium that is reactive to PAS and AB. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells that are reactive only to PAS. The intestine has a simple columnar epithelium with a brush border and goblet cells that are reactive to PAS and AB. Somatostatin, serotonin and cholecystokinin immunoreactive cells were identified throughout the DT.This study revealed adaptations for the species' diet and showed that the distribution and relative frequency of immunoreactive cells are similar to those of other fish.

The ecology of sympatric African pike, Hepsetus odoe (Hepsetidae), and tiger fish, Hydrocynus forskahlii (Characidae), were compared during high (May-August) and falling water (September-December) conditions in the Upper Zambezi R. drainage of Zambia. Both species were common in the central and southern regions of the river and associated floodplain, and Hydrocynus was common in the northern region in swift flowing tributaries where Hepsetus was rare. Hepsetus inhabited vegetated environments of river backwaters, lagoons, and sluggish tributaries, whereas Hydrocynus occupied the open water of the main river channel almost exclusively. During the period of annual flooding, juveniles of both species coexist in flooded savanna regions. Size distributions of adult Hydrocynus and Hepsetus changed relatively little between high and low water conditions. Stomach contents analysis indicated that adult size classes of both species are almost entirely piscivorous, and both show diet shifts with changes in size. Only very small seasonal diet shifts were noted. Approximately 50% of the diet of Hepsetus consisted of haplochromine cichlid fishes, but also included large numbers of tilapine cichlids and mormyrids, Hydrocynus consumed primarily cichlid fishes, but also consumed large percentages of Hepsetus and small characid fishes. Small size classes of Hepsetus fed heavily on small machokid catfishes (Synadontis spp.) and later shifted to a diet of cichlids and mormyrids, and small Hydrocynus preyed heavily on Barbus spp. (Cyprinidae), small characids, and mormyrids. Ratios of prey length-predator length averaged approximately 0·26 for Hydrocynus and nearly 0·40 for Hepsetus. The large potential for food resource competition appears not to be realized due to a very high degree of habitat partitioning between larger size classes of the two species. At the interface between river backwaters and channel habitats, Hydrocynus is a significant predator of Hepsetus, a factor that should further restrict the occurrence of the latter in open areas of the main channel.

Summary Gill anomalies in three common fish species of different taxonomic order, habitat dwelling and feeding habits (one Characiformes, Oligosarcus hepsetus; one Siluriformes, Hypostomus auroguttatus; and one Perciformes, Geophagus brasiliensis) from a eutrophized tropical river in south-eastern in Brazil were compared. The aim of this study was to search for sentinel species that could be used as potential biomarkers of environmental quality. Most fish had gills with histological changes, namely epithelial lifting, interstitial oedema, leucocyte infiltration, hyperplasia of the epithelial cells, lamellar fusion, vasodilatation and necrosis. On the other hand, lamellar blood congestion and lamellar aneurysm, which are more serious and often irreversible changes, were recorded for the water column carnivorous O. hepsetus and, to a lesser extent, for the bottom-dwelling detritivorous H. auroguttatus. A histopathological alteration index (HAI) based on the occurrence and severity of gills anomalies indicated that O. hepsetus (mean score = 11.4) had significantly higher values (Kruskall– Wallis H2,41 = 15.95, P = 0.0003) compared with G. brasiliensis (mean score = 7.0). Overall, the omnivorous G. brasiliensis had comparatively lesser occurrence of most gill anomalies compared with other two species, being less suitable as biomarker of environmental quality. In contrast, the water column– dweller O. hepsetus (water column) and the bottom-dweller H. auroguttatus had gills most susceptible to changes, making them more suitable for using as histological biomarkers of the environmental quality in entrophized tropical rivers.

The new species herein described, collected in the Jacui and Uruguay River basins, Rio Grande do Sul, Brazil, can be distinguished from the already known species of the genus, but Oligosarcus jenynsii, O. perdido, O. acutirostris, O. solitarius and O. hepsetus, by the number of perforated lateral line scales. It shares with the first two species the absence of a premaxillary foramen, present in the last three species and differs from O. jenynsii by having a smaller orbital diameter and the tip of the pectoral fin failing to reach the pelvic-fin origin, and from O. perdido by the presence of more horizontal scale rows around the caudal peduncle. A especie nova descrita aqui, coletada nas bacias dos rios Jacui e Uruguai, Rio Grande do Sul, Brasil, pode ser diferenciada das especies ja conhecidas do genero, com excecao de Oligosarcus jenynsii, O. perdido, O. acutirostris, O. solitarius e O. hepsetus, pelo numero de escamas perfuradas ao longo da linha lateral. Compartilha com as duas primeiras especies a ausencia de um forame no premaxilar, presente nas tres ultimas especies e difere de O. jenynsii por possuir o diâmetro orbital menor e a extremidade da nadadeira peitoral nao alcancando a origem da nadadeira pelvica e de O. perdido pela presenca de mais series horizontais de escamas ao redor do pedunculo caudal.

Concentrations of organic (OrgHg) and inorganic mercury (InorgHg) were assessed in different fish tissues (liver, muscle, kidney, gut and gonads) and trophic levels collected in an impacted tropical reservoir in southeastern Brazil. Organic mercury concentrations in muscle were remarkably higher in the carnivorous species Hoplias malabaricus and Oligosarcus hepsetus. The ratios of OrgHg in relation to total mercury (%OrgHg) in muscle also varied according to the species trophic level: 93% for carnivores, 84% for omnivores, 73% for algivores/planktivores and 58% for detritivores. The %OrgHg in the gut tissue of carnivores (78%) was much higher than that found in omnivores (30%), possibly reflecting a process of trophic biomagnification in the reservoir. On the other hand, the InorgHg concentrations in muscle decreased with the trophic level increase, suggesting that this form of mercury did not biomagnify through the food web. Gonads contained the least total mercury, and approximately all of this mercury was represented by the organic form (83 to 98%). The kidney and the liver of all fish species contained less than 50% OrgHg. We suggest that the low %OrgHg in the liver is related to different capacities or strategies of OrgHg detoxification by the fish. Concentrações de mercúrio orgânico (OrgHg) e inorgânico (InorgHg) foram avaliadas em diferentes tecidos e níveis tróficos de peixes (fígado, músculo, rim, trato digestivo e gônadas) coletados em um reservatório tropical impactado, no sudeste do Brasil. Concentrações de OrgHg no músculo foram notavelmente maiores em carnívoros (Hoplias malabaricus e Oligosarcus hepsetus). As porcentagens de OrgHg em relação ao mercúrio total (%OrgHg) no músculo também variaram de acordo com o nível trófico das espécies: 93% para os carnívoros, 84% para os onívoros, 73% para os algívoros/planctívoros e 58% para os peixes detritívoros. Além disso, a %OrgHg encontrada no trato digestivo dos peixes carnívoros (78%) foi substancialmente superior a encontrada nos onívoros (30%), possivelmente refletindo um processo de biomagnificação trófica no reservatório. Por outro lado, as concentrações de InorgHg no músculo diminuíram com o aumento do nível trófico, sugerindo que esta forma do mercúrio não biomagnificou ao longo da cadeia alimentar. As gônadas apresentaram as menores concentrações de mercúrio total e grande parte deste estava na forma orgânica (83 a 98%). Por outro lado, rins e fígado de todas as espécies de peixes apresentaram menos que 50% de OrgHg. Sugere-se que a baixa %OrgHg no fígado possa estar relacionada às diferentes capacidades ou estratégias de destoxificação do OrgHg nesses peixes

A four months research survey of arthropod pests infesting dried fish sold in a tropical urban community market (Ogige), Nsukka, Ngeria showed that 10 genera o dried freshwater fish (Synodontis, Hemisynodontis, Oreochromis, Hepsetus, Gymnarchus, Labeo, Protopterus, Heterobranchus, Alestes, Heterotis) and two species of cod fishes sold in the market were arthropod infested. The pests were extracted by iumination and cracking methods and identifed using relevant taxonomic keys. Voucher specimens were kept n the Museum of Natural History, Department of Zoology University of Nigeria. Each of the fish genera harboured at least one of the following arthropods: Dermestes maculatus, Necrobia rufipes, Lardoglyphus konoi, Theridion saxatile and Tribolium castaneum. T. castaneum was found only in fish bones in the stall. Besides the resident pests, Peripaneta americana, Lucilia spp, Calliphora spp and Musca domestica were visiting pests of the dried fish sampled. D. maculatus was the dominant resdent pest accounting or 57.07 % of the colected arthropods whle Necrobia rufipe was next in importance, accounting for 21.54 %The pests were identified using keys and voucher methods.Keywords: Arthropod pests, Visiting pest, Resident pest, Dried fish, Cod, Fish bone, Urban market

Coastal lagoons are important systems for freshwater, estuarine and marine organisms; they are considered important zones of reproduction, nursery and feeding for many fish species. The present study investigates the fish assemblages of the natural reserve of Dzilam and their relationship with the hydrologic variables. A total of 6 474 individuals (81 species) were collected, contributing with more than 50% considering the Importance Value Index (IVI), Sphoeroides testudineus, Fundulus persimilis, Anchoa mitchilli, Eucinostomus gula, Eucinostomus argenteus and Mugil trichodon. Differences in species composition were found between seasons the highest during the cold fronts. Spatially, differences were related with the presence of freshwater seeps, the highest in the ecological characterized eastern part and the lowest with higher difference in specific composition located in the western part of the internal zone, due to a higher abundance and dominance of L. rhomboides. Salinity and temperature were the variables that presented a higher influence in the distribution of some pelagic species such as A. mitchilli and A. hepsetus. Because of the abundant freshwater seeps characteristic of the coastal lagoons of Yucatan Peninsula their community structure and fish assemblage display spatial and temporal differences in specific composition. Rev. Biol. Trop. 57 (1-2): 89-103. Epub 2009 June 30.Las lagunas costeras son sistemas importantes para muchas especies de organismos dulceacuícolas, estuarinos y marinos, ya que son consideradas zonas de reproducción, refugio y alimentación de muchas especies de peces. El presente estudio analizó los ensamblajes de la comunidad íctica de la reserva de Dzilam y su relación con las variables hidrológicas. Se capturaron un total de 6 474 individuos (81 especies), en donde Sphoeroides testudineus, Fundulus persimilis, Anchoa mitchilli, Eucinostomus gula, Eucinostomus argenteus and Mugil trichodon contribuyeron con más del 50% del Indice de Valor de Importancia (IVI). Las diferencias en composición de especies se encontraron entre temporadas, la mayor durante los nortes. Espacialmente, las diferencias fueron relacionadas con la presencia de afloramientos de agua dulce, la mayor en la zona Este de la laguna y la menor con mayor diferencia en composición específica se localizó en la parte Oeste de la zona interna, esto debido a la gran abundancia y dominancia de una sola especie (L. rhomboides). La salinidad y la temperatura fueron las variables que presentaron la mayor influencia en la distribución de algunas especies pelágicas como son A. mitchilli y A. hepsetus. Debido a la abundancia de afloramientos de agua dulce, característicos de las lagunas costeras de la Península de Yucatán, los ensamblajes de peces muestran diferencias espaciales y temporales en la composición específica.

In Laguna Joyuda, Puerto Rico, 24-h trawl surveys were conducted to test the hypothesis that there is no diel variation in the catch rate of fishes and penaeid shrimps in a turbid, microtidal estuary relatively free of visual predation. The null hypothesis was not rejected for the two most abundant fishes in the lagoon, Eucinostomus gula (Gerreidae) and Achirus lineatus (Bothidae). Conversely, the total number of fishes, Diapterus rhombeus (Gerreidae), and the engraulids Anchoa cubana and A. hepsetus were collected in significantly higher numbers during hours of darkness. Total penaeid catch was significantly higher in night than in day collections. The most abundant species were Penaeus notialis and P. subtilis, both of which appeared to be strong daytime burrowers. Small penaeids demonstrated greater diel variation in trawl capture rate than larger (subadult) shrimps. Diel variation in capture rate was related to habitat associations of individual species. Fauna resident in the very turbid lagoon demonstrated no diel variation in activity patterns and trawl susceptibility. Those species which spend only the early part of their lives in the lagoon, or live in both turbid and clear water, had significant diel variation in activity and trawl catchability.

The characid genus Oligosarcus consists of 20 described species distributed throughout most of South American river basins below 14o south latitude. This study focus on the phylogenetic relationships of the species of Oligosarcus based on the analysis of osteological characters to provide data to discuss the biogeographic history of the genus. The analysis resulted in a single most parsimonious tree with 152 steps (CI= 0.355 and RI= 0.600). The 18 included Oligosarcus species were hierarchically organized into 17 clades. A minimal age of 15 Ma for the genus is suggested based on the putatively cladogenetic event represented by the continued shortening of the Eastern Cordillera that established the eastern boundary of the modern central Andean plateau and was responsible for cladogenesis between the common ancestor of O. schindleri + O. bolivianus versus the remaining congeners. There is a pronounced disjunction in the upland species distribution by the lowland areas of the Chaco-Pantanal basin. This indicates that upland habitats (headwater streams) are preferential habitats for a set of species including O. argenteus, O. bolivianus, O. brevioris, O. paranensis, O. perdido, O. pintoi, O. planaltinae, O. brevioris, and O. schindleri. Fragmentation of populations of O. pintoi and O. perdido are at least 2.5 Ma old, since the origin of the upper Paraguay depression clearly promoted the present-day observed disjunction in the distribution of these species. The lowland Oligosarcus species are all included in a single clade but the obtained results suggest that fragmentation of upland versus lowland components of the genus was not causally related to a single vicariant event. The available fossil record of Oligosarcus indicates that the genus already occurred in the coastal plain at about 2.3 to 1.25 Ma. The sister-group relationship between O. hepsetus and O. longirostris provided additional evidences of the so-called historical affinities between the SE Brazilian coastal plain and the Rio Iguacu drainage basin.

Six reproductive classes of male Oligosarcus hepsetus (Cuvier, 1829), a medium-sized carnivorous Characiform species, are described based on macroscopic and histological techniques. A total of 175 individuals were caught monthly between April 2001 and June 2002 in the Lajes Reservoir, Brazil, one of the largest impoundment areas in the state of Rio de Janeiro. The reproductive classes were based upon changes in the testicular morphology and stages of germinative cells, i.e., resting, early maturing, late maturing, mature, partially spent and totally spent. Fish in the resting class showed testes with spermatogonia and spermatocytes along the wall of seminal lobules, while spermatids were present in the lumina of the lobules. During early maturing, active spermatogenesis occurs throughout the testis; in the late maturing and mature classes, the lobules are swollen with sperm that are typical of fish in breeding condition. Spent testes presented seminal lobules with residual spermatozoa, coinciding with decreasing GSI and greatly reduced sperm production. Overall, the testicular morphology and class of maturity development of O. hepsetus in the Lajes reservoir did not differ significantly from those of closely related species in other lentic environments. Lower GSI values in the oligotrophic Lajes reservoir than in other eutrophic natural lakes suggest that this species may be modifying this aspect of its reproductive strategy in response to the artificial environment. Seis classes de maturação dos testículos de Oligosarcus hepsetus (Cuvier, 1829), um Characiforme carnívoro de médio porte, foram descritas com base em técnicas macro e microscópicas. Um total de 175 indivíduos foi capturado mensalmente entre abril/2001 e junho/2002 no Reservatório de Lajes, Brasil, uma das maiores áreas represadas do Estado do Rio de Janeiro. As classes reprodutivas foram estabelecidas de acordo com mudanças na morfologia dos testículos e nos estádios das células germinativas: repouso, maturação inicial, maturação final, maduro, parcialmente esvaziado e totalmente esvaziado. Os testículos da classe em repouso apresentaram espermatogônias e espermatócitos ao longo da parede dos túbulos seminíferos, enquanto as espermátides foram encontradas no lúmen dos túbulos. Nos testículos em maturação inicial, a espermatogênese é intensa; em maturação avançada e maduros, os túbulos estão repletos de sêmen, que são característicos de peixes aptos a reprodução. Testículos esvaziados apresentaram sêmen residual nos túbulos seminíferos, coincidindo com a diminuição do IGS e com uma grande redução na espermatogênese. Em geral, a morfologia dos testículos e o desenvolvimento das classes de maturação de O. hepsetus no Reservatório de Lajes não diferiram de espécies similares em outros ambientes lênticos. Os menores valores do IGS para o reservatório oligotrófico de Lajes, quando comparados com lagos naturais eutróficos, sugerem que O. hepsetus pode estar alterando este aspecto de sua estratégia reprodutiva no ambiente artificial.

We assessed spatial and seasonal changes in the diet of Oligosarcus hepsetus in order to describe the strategy developed by this species that allows their very high abundance in Lajes reservoir, Rio de Janeiro, Brazil. Fish samplings were carried out using gill nets, deployed during ca. 12 and 24 hours, between April 2001 and May 2002. A total of 289 individuals were examined, of which 97 showed gut contents. We used the index of relative importance (IRI) to compare probable dietary shifts, and the frequency of occurrence (% OC) to analyze possible ontogenetic influences on feeding. O. hepsetus showed carnivorous habits, feeding preferably on fish and insects, the latter of which occurred in 71.0% of the guts presenting contents. O. hepsetus consumed different items along the three reservoir zones: insects (61.0% IRI) and Cichla monoculus (38.9% IRI) in the lower zone; Lepidoptera (57.0% IRI) in the middle zone; and C. monoculus (77.0% IRI) in the upper zone. Food items changed seasonally with C. monoculus predominating in autumn 2001, and Hymenoptera and Lepidoptera in the winter. In spring almost all food was Lepidoptera (99.8% IRI), while in the summer Hemiptera dominated in the diet. In autumn 2002 Hemiptera (97.0% IRI) was dominant, in significant contrast with the previous autumn. Individuals smaller than 190 mm SL fed heavily on insects, while fishes predominated in the diet of individuals larger than 190 mm SL. Shifts in prey-capture ability among length classes suggest decreasing intraspecific competition. A higher food plasticity seems to be the strategy employed by this opportunist species, which used food resources available in the reservoir. Foram analisadas variações na dieta de O. hepsetus conforme comparações espaciais e sazonais, com o objetivo de descrever a estratégia desenvolvida por essa espécie que permite sua elevada abundância no reservatório de Lajes, Rio de Janeiro, Brasil. As amostras foram coletadas utilizando redes de espera com permanência aproximadamente de 12 e 24 horas, no período entre abril de 2001 e maio de 2002. Dos 289 exemplares capturados, 97 peixes continham alimento no estômago. A análise foi baseada no índice de importância relativa (IIR), enquanto eventuais influências ontogenéticas foram determinadas pela freqüência de ocorrência (% FO). O. hepsetus apresentou hábito alimentar carnívoro, alimentando-se preferencialmente de peixes e insetos. O item Insetos apresentou relevante participação na dieta, ocorrendo em 71% dos estômagos que continham alimento. O. hepsetus consumiu diferentes itens entre as três zonas do reservatório: insetos (61% IIR) e Cichla monoculus (38,9% IIR) na zona baixa; Lepidoptera (57% IIR) na zona intermediária; e C. monoculus (77% IIR) na zona alta. No geral, ocorreram diferenciações durante todo o ciclo sazonal, em que C. monoculus predominou no outono de 2001 e Hymenoptera e Lepidoptera, no inverno. Na primavera, a alimentação foi basicamente constituída por Lepidoptera (99,8% IIR), enquanto no verão, Hemiptera predominou na dieta. No outono de 2002 foi registrado 97% IIR para Hemiptera, diferindo do outono anterior. Indivíduos menores que 190 mm de comprimento-padrão (CP) consumiram preferencialmente insetos, enquanto os espécimes de maior tamanho (> 190 mm CP) alimentaram-se principalmente de peixes. Mudanças na captura de presas entre classes de tamanho sugerem diminuição da competição intra-específica. A alta plasticidade na alimentação parece ser uma estratégia usada por essa espécie oportunista, consumindo os recursos alimentares disponíveis no reservatório.

Hepsetus odoe (Bloch, 1794) Salmo odoe Bloch, 1794: 122, pl. 386. LOCALITÉ TYPE. — Côte de Guinée (c’est-à-dire Afrique occidentale). DESCRIPTION. — Corps allongé, de taille moyenne à grande (maximum observé 700 mm LT en Côte d’Ivoire). Dessus de la tête plat, dorsale rayonnée située très en arrière, ce qui donne à ce poisson une allure de brochet européen. Bouche grande et mâchoires garnies de dents coniques sur trois rangées. Un repli dermique triangulaire à la mâchoire inférieure et un plus petit arrondi à la mâchoire supérieure. DISTRIBUTION. — Espèce largement répandue dans toute l’Afrique occidentale et centrale jusqu’au Zambèze, aussi bien dans les cours d’eau de savanes que dans ceux de forêts. Au mont Nimba, deux exemplaires jeunes de 25 et 158 mm ont été capturés dans le Nipoué à Yéalé (400 m) et dans le Boan à Gopoupleu (400 m). Ils ont été cités par Daget (1963: 575) et Daget & Iltis (1965: 59, fig. 32)., Published as part of Résumé, Jacques Daget, 2003, Les Poissons Actinoptérygiens du mont Nimba, pp. 581-596 in Mémoires du Muséum national d'Histoire naturelle 190 on page 583, {"references":["DAGET J. 1963. - Poissons (Deuxieme note), in La Reserve naturelle integrale du mont Nimba, V. Memoires de l'Institut franCais d'Afrique noire 66: 573 - 600.","DAGET J. & ILTIS A. 1965. - Poissons de Cote d'Ivoire (eaux douces et saumatres). Memoires de l'Institut franCais d'Afrique noire 74, 385 p."]}

PubMedID: 12475070 Heavy metal (Cd, Cr, Cu, Fe, Pb, Zn) concentrations in the muscle, gill and liver of six fish species (Sparus auratus, Atherina hepsetus, Mugil cephalus, Trigla cuculus, Sardina pilchardus and Scomberesox saurus) from the northeast Mediterranean Sea were measured and the relationships between fish size (length and weight) and metal concentrations in the tissues were investigated by linear regression analysis. Metal concentrations (as µg/g d.w.) were highest in the liver, except for iron in the gill of Scomberesox saurus and lowest in the muscle of all the fish species. Highest concentrations of Cd (4.50), Cr (17.1) and Pb (41.2) were measured in liver tissues of T. cuculus, Sardina pilchardus and A. hepsetus, respectively. The liver of M. cephalus showed strikingly high Cu concentrations (202.8). The gill of Scomberesox saurus was the only tissue that showed highest (885.5) iron concentrations. Results of linear regression analysis showed that, except in a few cases, significant relationships between metal concentrations and fish size were negative. Highly significant (P

Spatial distribution of fish assemblages in Lajes Reservoir, a 30 km2 impoundment in Rio de Janeiro State (Lat. 22 degrees 42'-22 degrees 50'S; Long. 43 degrees 53'-44 degrees 05'W) was assessed to detect patterns of available habitat use by the fish. A standardized monthly sampling program was carried out from January to December 1994 at three zones of the reservoir (upper, near tributary mouths; middle; and lower, near the dam). Fishes were caught by gillnets, (50 m long, 3 m height), with mesh ranging having from 25 to 45 mm between knots, submerged during 12 hours. A total of 5,089 fishes were collected comprising 15 species, 14 genera and 9 families. Loricariichthys spixii, Astyanax bimaculatus, Parauchenipterus striatulus. Astyanax fasciatus parahybae, Oligosarchus hepsetus, Rhamdia parahybace, Hypostomus affinis. and Geophagus brasiliensis were the most abundant species, each contributing above 1% of the total number. Loricariichthys spixii was the dominant species, contributing over 80% of total number and biomass. Fish abundance, number of species, and biomass were higher in the upper zone, but differences from this overall pattern were shown by some species. Loricariichthys spixii and Rhamdia parahybae were more abundant in the upper zone, while all other species showed no differences in their abundance among the zones. Seasonal environmental variables of temperature, pH, transparency, and water level did not show a clear association with fish occurrence. Most fish used the different zones of the reservoir with no clear sign of spatial separation. High dominance of L. spixii. reduced abundance of reolific species Leporinus copelandii and Cyphocharax gilberti, and presence of introduced species such as Cichla monoculus and Tilapia rendallalli are indications of antropic effects in the fish community.

A new species of philometrid nematode, Philometroides africanus sp. n., is described from female specimens found encapsulated in gill arches and inner surface of gill covers of the African pike, Hepsetus odoe (Bloch), an endemic freshwater fish in Africa, from the Okavango River and Delta in Botswana. This new nematode is characterised mainly by a markedly small and plump body of gravid females (body length 6-9 mm), a separate anterior oesophageal bulb, a conspicuously small oesophageal gland, presence of four pairs of very small submedian cephalic papillae, and absence of any caudal processes. The prevalence of P. africanus in African pike of the Okavango Delta was 29%, with the intensity 1-8 (mean 3) encapsulated nematodes per fish. The genus Margolisianum Blaylock et Overstreet, 1999 is considered a junior synonym of Philometroides Yamaguti, 1935 and, consequently, its type species is transferred to the latter as Philometroides bulbosus (Blaylock et Overstreet, 1999) comb. n.

Photoreceptors of anchoviesAnchoa mitchilliandA. hepsetusconsist of normal rods and two unusual kinds of cones. The latter lie in single vertical rows, and the rods lie between them. Both participate in photomechanical movements, and movement of the cones is closely coordinated with that of pigment cell processes. There are long cones having a cuneate outer segment and short cones having a bilobed outer segment. Long and short (bifid) cones alternate within a row and are staggered between adjacent rows. Both kinds possess calycal processes; long cones have a lateral sac or accessory outer segment. The long and short cones are associated to form a structure called a cone unit, which consists of the outer segment and ellipsoid of a long cone joined to two outer segment lobes of two adjacent short cones. The lobes of the latter are partly enclosed by the ellipsoid of the long cone. A cone row consists of a row of cone units isolated from each other by processes of the pigment epithelium containing stacks of guanine crystals which form a tapetum. Dorsal and ventral faces of inner segments have contact zones characterized by subsurface cisternae. Lamellae in the cone outer segments are arranged longitudinally with respect to the cell axis and short and long cone lamellae are perpendicular to each other; lamellae of the rods are transverse. Long cone lamellae are perpendicular to the cone row, and in the central retina are almost horizontal to the long axis of the body. Some vesicular/tubular structures also occur in the cone outer segments. Outer and inner segments of cones are joined by a broad connecting structure containing a stalk and root portion corresponding to a modified and reduced cilium shaft and centriole, respectively. The rod has a typical connecting stalk. Mitochondria of cone ellipsoids have expanded perimitochondrial spaces between outer and inner membranes. The organization of the anchovy cones is compared with that of other vertebrates. It is suggested that the cone unit may be a two channel analyser for the detection of plane polarized light and function in conjunction with the overlying reflector of regularly arranged platelets.

The development of the jugular and cerebral veins and adjacent lymphatic vessels in Hepsetus, Salmo, Amia, Acipenser, Neoceratodus, Scyllium and Squalus has been studied on a large embryological material. The reconstruction method has been applied. There has been much confusion in the literature on head veins. This is partly due to the rather schematic investigations of e.g. van Gelderen, and partly to the publications of de Beer and Holmgren, paying no regard to the lymphatic vessels. The currently new features on the v. capitis medialis are that in adult fishes a larger part of the vein remains than was earlier believed. It usually consists of three portions. No secondary vein takes part in the constitution of the jugular vein, as was supposed by de Beer, Holmgren and others. In actinopterygians the secondary vein is in reality represented by the anterior portion of the v. cardinalis anterior as well as of all the v. capitis lateralis, and in elasmobranchs it is only represented by the former portion. The elasmobranchian (except Squalus) jugular vein is instead formed from the v. capitis lateralis, and in teleostomes and Squalus it is developed from two veins, viz. the anterior portion of the v. capitis medialis and all the v. capitis lateralis. The latter vein is formed from two (teleostomes) or three (elasmobranchs) loops. The v. cardinalis anterior becomes completely atrophied in Squalus, and partly atrophied in Acipenser, Amia and Neoceratodus. The development of the three main cerebral veins is described. van Gelderen's classification of the v. cerebralis media is criticized. And so also is his hypothesis for the evolution of the head veins in fishes. It is suggested that the Hepsetus type is primitive and that the Acipenser and Amia types have evolved from it or from a similar type. Neoceratodus and Squalus have rather specialised types, which seem to have evolved separately right from the base of the system.

The ictiologic survery of the fauna of the Jacuí and Jacuizinho rivers, (RS – Brazil) lead to the identification of twenty species, Astyanax bimaculatus and Astyanax fasciatus and as well as Hemiancistrus sp being more abundant and uniformly distributed during the months of collet while Symbranchus marmoratus and Oligosarchus hepsetus were the more seldom found fishes.

MONOD, T. 1968. Le complexe urophore des poissons teleosteens. Mem. Inst. Fond. Afrique Noire, No. 81. NELSON, G. J. 1969. Gill arches and the phylogeny of fishes, with notes on the classification of vertebrates. Bull. Amer. Mus. Nat. Hist., 141:479-552. NYBELIN, 0. 1968. The dentition in the mouth cavity of Elops, p. 439-445. In: Current Problems of Lower Vertebrate Phylogeny. T. 0rvig, ed. Almqvist and Wiksell, Stockholm. REGAN, C. T. 1911. The classification of the teleostean fishes of the Order Ostariophysi. I. Cyprinoidea. Ann. Mag. Nat. Hist., (8)11: 553-577. RIDEWOOD, W. G. 1905. On the cranial osteology of the clupeoid fishes. Proc. Zool. Soc. London, 1904(2):448-493. ROBERTS, T. R. 1967. Tooth formation and replacement in characoid fishes. Stanford Ichthyol. Bull., 8:231-247. . 1969. Osteology and relationships of characoid fishes, particularly the genera Hepsetus, Salminus, Hoplias, Ctenolucius, and Acestrorhynchus. Proc. Calif. Acad. Sci., (4)36: 391-500.