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Two new Phenacogrammus are described from the Ndzaa River, a small left-bank tributary of the Mfimi-Lukenie River in the central Congo basin. They share with P. deheyni, a congener endemic to the Cuvette Centrale to the north, a prominent anterior expansion of the first pleural rib; a feature interpreted here as a synapomorphy diagnostic for this species assemblage. The two new species are readily differentiated from P. deheyni based on differences in pigmentation patterning, a lower number of scales in longitudinal series (26–28 vs. 29–33) and a longer head length (m. 24.9% SL vs. 21.7 and 23.2% SL). Phenacogrammus flexus, new species, is distinguished from all congeners in the possession of 6 (vs. 7) supraneural bones, and a characteristic zigzag pattern of black pigmentation along and below the midline extending from the posterior border of the opercle to the base of the caudal peduncle. While no unambiguous morphological autapomorphies have been located to diagnose P. concolor, new species, it is nonetheless readily distinguished from all congeners, except P. deheyni and P. flexus, in the possession of a prominent anterior expansion of the first pleural rib. It differs from both P. deheyni and P. flexus in the absence of a dominant pigmentation patterning over the flanks and caudal peduncle. Additionally, it differs from P. flexus in a shallower body depth (m. 24.9% vs. 27.0% SL) and in the possession of 7 (vs. 6) supraneurals. The three species exhibit extensive divergence in mt-COI sequence (P. flexus vs. P. concolor 10.2%–11%; P. flexus vs deheyni 12.9%–13.5%; P. concolor vs. deheyni 11.3%–12.9%). Furthermore, analysis of shape variation utilizing geometric morphometrics indicates that each species differs significantly in body shape.

The present study aimed to investigate the karyotype and molecular sex differences in Brycinus nurse. Analysis of 430 metaphases spreads from 12 specimens revealed that the diploid chromosome number is 44 chromosomes and the proposed karyotype formula is n = 3 M + 3 SM + 16 A, FN = 56. No morphologically differentiated heteromorphic sex chromosomes were observed. On the other hand, 29 primers of three molecular markers (RAPD, SCoT and ISSR) were tested to differentiate between males and females of B. nurse. From all tested primers only two primers (OPI-18 and SCoT-18) successfully generated female specific bands in the bulked DNA samples which further confirmed using individual DNA samples. According to molecular analysis result in this study it seems that females of B. nurse are the heterogametic gender (ZW) and males of B. nurse are the homogametic gender (ZZ). In the future, SCoT marker can be used as suitable and powerful marker in genetic analysis studies in fish.

To investigate the presence of cryptic diversity in the African longfin-tetra Bryconalestes longipinnis, we employed DNA barcoding in a phylogeographic context, as well as geometric morphometrics, documenting for the first time genetic and body shape variation in the species. Analysis of cytochrome oxidase I gene (coI) sequence variation exposed extremely high levels of genetic differentiation among samples from across the geographic range of the species (up to 18%), certainly much greater than the traditionally employed c. 3% sequence divergence heuristic threshold for conspecifics. Phylogeographic analyses of coI data revealed eight clusters/clades that diverge by >4% and up to 18% (p-distance), potentially representing cryptic members of a species complex. A clear biogeographic pattern was also uncovered, in which the two main coI lineages corresponded geographically with the upper Guinea (UG) and lower Guinea (LG) ichthyofaunal provinces of continental Africa, respectively. Within each of these main lineages, however, no apparent phylogeographic structuring was found. Despite strong genetic differentiation, there is considerable overlap in body shape variation between UG and LG populations. For the most part, morphological variation does not match the strength of the molecular phylogeographic signal. Therefore, the ability to reliably utilise external body shape for regional delimitation remains elusive. Further anatomical investigation appears necessary to establish whether compelling diagnostic morphological features do exist between the divergent lineages of the B. longipinnis complex uncovered in this study.

In tropical Africa, and particularly in Benin, running waters dwell a high and valuable fish fauna that are almost unknown, but under severe degradation. The current study inventoried the fish biodiversity of the Okpara stream, the main tributary of the Oueme River (the largest in Benin), in order to fill the gap of ichthyological data and to improve habitat protection, species conservation and valorization. During 18 months, fish samplings were made monthly with various fishing gears on five (5) locations. A total of 53 fish species belonging to 30 genera, 14 families and 7 orders were recorded among a total of 9552 individual fish collected. The most representative families were Mormyridae with 9 species and Cichlidae with 8 species, then follow Mockokidae, Clariidae, Cyprinidae and Alestidae with 6, 6, 6, 4 species, respectively. Families such as Anabantidae, Bagridae, Claroteidae, Malapteruridae, Polypteridae and Schilbeidae were less represented and individually included 2 species. The Hepsetidae and Aplocheilidae were represented by one (1) species, respectively the African pike, Hepsetus odoe and Epiplatys bifasciatus. A holistic scheme of ecosystem management and species conservation requires a complete knowledge on the fish community structure, eco-toxicology and species ecological status.Read Complete Article at ijSciences: V82019042052 AND DOI: http://dx.doi.org/10.18483/ijSci.2052

Diet of 300 specimens of Bryconaethiops boulengeri from Djiri River (Congo Brazzaville) caught with cash nets was studied according to the size of fish, sampling stations and hydrological season. Sampling focused on twelve annual withdrawals made during three years. The relative importance index combining numerical and weight percentages of occurrence was calculated and also the sex ratio was evaluated. Bryconaethiops boulengeri consumes terrestrial and aquatic insects and everything that falls into the water (birds feathers, plant debris, fruits, etc.). The percentage of emptiness is 9.66% of the three sampling stations selected; no significant difference in diet was observed whatever the season.

Summary The monogenean, Afrogyrodactylus ardae sp. n., is described from the African tetra, Rhadbalestes septentrionalis (Characiformes: Alestidae), collected from the Niokolo Koba and Gambie Rivers in the Niokolo-Koba National Park, Senegal during 2008. The newly described species can be differentiated from three known species of the genus based on the dimensions of its opisthaptoral hard parts, having the smallest ones, and based on the shape of the marginal hooks sickle. The present finding represents a new host record for the genus Afrogyrodactylus.

Ichthyofaunal distribution was studied in the Musolo River system, a small affluent tributary of the Congo River flowing into Pool Malebo (Democratic Republic of the Congo). Twelve ecological stations were sampled, of which eight were located in the Musolo main-channel and four in the Fushi River, a principal tributary of the Musolo. Each station was sampled four times over a two-year period, with fishing techniques following standardized methods utilizing dip and cast nets, and nine environment variables were measured at each station. Fifty-three fish species belonging to 36 genera and 16 families were collected with the Alestidae, Distichodontidae, Cichlidae, Cyprinidae, Mormyridae, and Mochokidae being the most diversified. Redundancy Analysis with forward selection coupled with Monte Carlo permutation tests (499 permutations) identified total dissolved solid (25.8%) and altitude (24.4%) as accounting for 50.2% of total variance (p < 0.05). The contribution of the two first axes was significant (F = 3.41; p = 0.004). Species richness increases from upstream to downstream. In general, the high value of Shannon’s diversity (1.07-2.67) and Equitability (0.62-0.96) indices at all sites, indicates that the examined stretch of the Musolo River system is in good ecological health, despite its location adjacent to the megacity of Kinshasa.

The Kahuzi-Biega National Park (KBNP), situated mainly in the Eastern Highlands Ecoregion of the Upper Congo basin, is drained by the Lowa and Ulindi rivers, and some western affluents of Lake Kivu. In this study, the first list of the fish diversity of these systems is provided based on museum collections and complemented, for the Lowa River system and the western Lake Kivu affluents, with recently collected specimens (2013-2017). A total of 118 species are reported from the Lowa basin, 22 from the Ulindi basin and seven from these Lake Kivu affluents. Within the Lowa and Ulindi, respectively, five and one species, all cichlids, have been introduced. Currently, 51 species are reported from within the park, only two of which have been reported from the highlands, i.e., Amphilius kivuensis from the Luha, the source of the Luka River, and Clarias liocephalus from the headwaters of the Lake Kivu' affluents. With a total of 30 species, Cyprinidae is by far the largest family, representing 25% of the total species diversity of the Lowa basin. It is followed by Mormyridae with 13 species (11%), Alestidae and Mochokidae with 10 species each (8%), Clariidae and Amphiliidae with eight species (7%), and Distichodontidae with six species (5%). Seven new species for science were discovered and 11 species were found to be endemic to the Lowa system. Although further exploration is needed, this underscores the importance of the KBNP in protecting the fish fauna of the Lowa basin but also highlights the park's limited coverage of the fish fauna of the Lowa basin.

Lake Kariba is a tropical lake with slight variations in seasonal temperature. Temperature is an important physical variable in the biology of both fish and their parasites. Currently, there is no information on the seasonal occurrence of fish parasites in Lake Kariba. The objective of this study was to investigate the seasonal occurrence of metazoan parasites in Hydrocynus vittatus in Lake Kariba, Zimbabwe. Twenty fish specimens were collected by seine netting per season between October 2014 and July 2015 in the Sanyati Basin, Lake Kariba, and examined for metazoan parasites. Mean water temperatures ranged from 24.1 °C to 31.2 °C with slight variations between the seasons. Metazoan parasites consisting of Monogenea ( Annulotrema pikei, Annulotrema pseudonili, Annulotrema bracteatum ), Nematoda ( Contracaecum larvae), Copepoda ( Lamproglena hemprichii ), Cestoda (larval cestodes, Ichthybothrium sp.) and Pentastomida (pentastomid larvae) were recorded. Larval cestodes were recorded in autumn and spring, while pentastome larvae were recorded in summer and spring. The Ichthybothrium sp. was recorded once in winter. Annulotrema pikei and A. pseudonili were observed on the gills and A. bracteatum on both the gills and the skin. Contracaecum larvae, L. hemprichii and A. bracteatum (from the skin) were recorded in all the seasons, with slight variations in prevalence, mean abundance and mean intensity. However, these variations were not statistically significant (analysis of variance or ANOVA, p > 0.05). The slight variations in occurrence of the parasites were probably because of the thermal stability of the lake where variation in temperature was small between seasons. Both A. bracteatum and Contracaecum larvae were aggregated on the fish host, whereas L. hemprichii exhibited a random distribution. Parasite diversity was at its highest during winter.

Background African tetras (Alestidae) belonging to Brycinus Valenciennes are known to be parasitized with monogeneans attributed to two genera, Annulotrema Paperna & Thurston, 1969 and Characidotrema Paperna & Thurston, 1968 (Dactylogyridae). During a survey of monogeneans parasitizing alestids, species of Characidotrema were collected in Cameroon, D. R. Congo, Senegal, South Africa, Sudan and Zimbabwe. This paper provides new morphological data and the first molecular analysis broadening our knowledge on the diversity of these parasites. Results Seven species (four known and three new) of Characidotrema are reported from two species of Brycinus: C. auritum n. sp. and C. vespertilio n. sp. from B. imberi (Peters); and C. brevipenis Paperna, 1969, C. nursei Ergens, 1973, C. pollex n. sp., C. spinivaginus (Paperna, 1973) and C. zelotes Kritsky, Kulo & Boeger, 1987 from B. nurse (Rüppell). Species identification was based on morphological analysis of the sclerotized structures supported by nuclear ribosomal DNA (partial 18S rDNA, ITS1, and 28S rDNA) sequence data. Morphological analysis confirmed that the most apparent character distinguishing species in the genus is the morphology of the male copulatory organ and vagina. Observations on the haptoral sclerotized elements of these parasites by means of phase contrast microscopy revealed the presence of a sheath-like structure relating to the ventral anchor, a feature that supplements the generic diagnosis of Characidotrema. Maximum Likelihood and Bayesian analyses of the large subunit (28S) rDNA sequences recovered Characidotrema species isolated from the two Brycinus hosts as monophyletic, and indicated a closer relationship of this group to monogeneans parasitizing African cyprinids (Dactylogyrus spp.) and cichlids (species of Cichlidogyrus Paperna, 1960, Scutogyrus Pariselle & Euzet, 1995, and Onchobdella Paperna, 1968) than to those from catfishes (species of Quadriacanthus Paperna, 1961, Schilbetrema Paperna & Thurston, 1968 and Synodontella Dossou & Euzet, 1993). The overall agreement between the morphological diversification of the MCOs and the molecular tree observed in this study indicates that significant phylogenetic signals for clarifying relationships among species of Characidotrema are present in the characteristics of the MCO. Conclusions It seems that intra-host speciation is an important force shaping the present distribution and diversity of Characidotrema but further studies are necessary to confirm this hypothesis and assess questions related to the phylogeny of these parasites. To identify potential co-speciation events, co-phylogenetic analyses of these monogeneans and their alestid hosts are required.

We here report the oldest remains (teeth) of the African tigerfish (Hydrocynus) from the Oued Méridja and Garet Dermchane sections, Hamada of Méridja deposits, in southwestern Algeria. The tigerfish, a large carnivorous fish today represented by several species in the freshwaters of Africa, was previously found in upper middle to upper Eocene deposits in Egypt and Libya. The remains described here are several million years older, being early to middle Eocene in age, and are associated with other fish elements including lungfish, polypterid, amiiform, possible cichlid, and Alestes and Brycinus material, along with several fish elements that cannot be associated with a specific taxon and some fragmentary amphibian bones. This represents the first detailed description of a freshwater fish assemblage from the Eocene of Algeria, although a short list of fish taxa from Eocene Algerian deposits was previously reported. Furthermore, these new Algerian fossils allow us to assess the hypothesized existence of an east–west or west–east hydrological connection between eastern and western parts of northern Africa. We suggest that the shared presence of tigerfish in the Eocene deposits of Algeria, Libya, and Egypt does not necessarily indicate a permanent (i.e., nonseasonal) connection east–west or west–east among these areas. Rather, the observed faunal similarities could have been the result of seasonal flooding that caused the dispersal of Hydrocynus and associated taxa across coastal flood plains.

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.

This study aimed to determine the growth patterns, mortality, and exploitation status of two species of Alestidae in the New Calabar River, Nigeria. For this purpose, fish samples were collected monthly from three landing sites from the local fishermen using gill nets (mesh sizes: 15-25mm), beach seine (mesh sizes: 2.3-10mm), and cast nets (mesh sizes: 15 -25mm). The length-weight relationship revealed exponent “b” value for Brycinus nurse was 3.54 and 3.21 for Brycinus macrolepidotus while the condition factors were 1.08 and 1.02 for Brycinus nurse and Brycinus macrolepidotus respectively. The growth parameters of Brycinus nurse asymptotic length (L) and growth coefficient (K) were 24.46 cm and 0.52 yr-1, respectively, while those for Brycinus macrolepidotus L was 28.88 cm and K was 0.22 yr-1. The reproductive load (L50/L) ratio was found to be 0.59 and 0.61 for B. nurse and B. macrolepidotus, respectively. Exploitation rate (E) for B. nurse was 0.26 and 0.11 for B. macrolepidotus while length-at-first capture (Lc) was 14.49 cm for B. nurse and 17.64 cm for B. macrolepidotus. The natural mortality was greater than the fishing mortality for both species and Logistic regression of the probability of capture routine values recorded for B. nurse were higher than that of B. macrolepidotus. Maximum exploitation rate (Emax) was less than 0.5 for both B. nurse (0.41) and B. macrolepidotus (0.42). These values were close to the maximum allowable limit; therefore, the species may be unsustainable when fishery intensifies in the future. To ensure sustainable exploitation of the two Alestid species in the area, fishing effort should be regulated.

The aim of this study was to analyze fish species caught by gill nets and fish diversity of the New Calabar River. Three sampling stations were set based on the coverage situation of the river and ichthyofauna associated with gill nets were sampled twice monthly from February to July 2018. A total of 3,251 fish specimens, representing 11 orders, 15 families, and 28 species, were captured. The order Perciformes was identified as the most abundant representing five families while the remaining had one family each. The fish family Cichlidae was the most represented with seven species, and other notable families were Alestidae, Clupeidae, and Mugilidae, representing three species each. Prominent among the fish caught monthly included Liza falcipinnis, Mugil cephalus, Sarotherodon melanotheron, Sarotherodon galilaeus, Coptodon guineensis, and Sardinella maderensis. The mean catch per unit effort (CpUE) ranged from 3.15±0.2 to 4.85±0.2 kg unit-1 day11. Results of diversity indices revealed that Shannon-Wiener index values varied between 2.64 and 2.82, Simpson diversity ranged from 0.07 to 0.10, and Pielou’s evenness index values ranged from 0.85 to 0.95. The values obtained in this study showed that the status of fish diversity in New Calabar River was stable.

Chalceus guaporensis is an endemic fish to the upper Madeira River whereas C. epakros is widespread in many rivers of the central and lower portions of the Amazon Basin, middle and upper Orinoco River Basin, the Essequibo River in Guyana and in the Nanay River in northern Peru. According to literature, both species do not occur in syntopy. We carried out ichthyological surveys along the Madeira River Basin and its rapids, and data on abundance, diet and habitat use were obtained for both species. Chalceus guaporensis and C. epakros are morphologically similar, occupying floodplain habitats and exploiting similar food resources. The former predominated upstream from the Jirau Fall, whereas the latter had most of its abundance bellow the last fall of the Madeira River; both species co-occurred along part of the rapids stretch and in the Machado River, but with strongly uneven abundances. This pattern may have developed in the past by speciation regarding the presence of the falls, while co-occurrence of the two species seems to be regulated by competitive interactions or maintained by slight differences in environmental requirements nowadays. The recent disruption of the Madeira River by two run-of-river dams built in cascade submerged a large portion of the rapids stretch and substituted it by semi-lenthic habitats created by the dam reservoirs, together with the construction of a fish passage. These environmental changes may allow the invasion of the upper reaches of the Madeira River by C. epakros, and disturb the population of endemic C. guaporensis. RESUMO Chalceus guaporensis é descrita como uma espécie endêmica do alto rio Madeira, enquanto C. epakros está amplamente distribuída em rios das porções central e inferior da bacia Amazônica, no médio e alto rio Orinoco, e nos rios Essequibo, na Guiana, e Nanay, no norte do Peru. A literatura não registra essas espécies como sintópicas. Expedições ictiológicas realizadas ao longo do rio Madeira e suas corredeiras nos deram a oportunidade de registrar a presença, abundância, habitat e dieta utilizadas por essas espécies. Chalceus guaporensis e C. epakros são muito similares morfologicamente, ocupam habitats inundáveis e apresentam espectro alimentar semelhante. A primeira espécie predominou a montante da cachoeira Jirau, enquanto que a segunda teve a maior parte de sua abundância registrada à jusante das cachoeiras do rio Madeira. Ambas espécies coocorreram ao longo de parte do trecho de corredeiras e no rio Machado, mas com abundâncias muito desiguais. Esse padrão pode ter se desenvolvido no passado, por especiação, em função da presença das corredeiras, enquanto a coocorrência das duas espécies parece ser regulada por interações competitivas ou mantida por diferenças sutis em requisitos ecológicos no tempo atual. O recente barramento do rio Madeira por duas hidrelétricas construídas em cascata submergiu uma grande porção do trecho de corredeiras e o substituiu por habitats semilênticos, criados pelos reservatórios das hidrelétricas a fio d’água, juntamente com a construção de uma passagem para peixes. Essas alterações ambientais podem permitir que C. epakros invada o trecho superior da bacia do rio Madeira, com possíveis impactos negativos sobre a população da espécie endêmica C. guaporensis.

Four new and four previously described species of Annulotrema were collected from the gills of four species (three genera, i.e. Alestes, Hydrocynus and Brycinus) of African tetras from Lake Turkana, Kenya: Annulotrema alestesnursi Paperna, 1973 from Brycinus nurse; Annulotrema ansatum n. sp., Annulotrema besalis Řehulková, Musilová and Gelnar, 2014, Annulotrema bipatens n. sp., Annulotrema cucullatum n. sp., Annulotrema nili Paperna, 1973, and Annulotrema pontile n. sp. from Hydrocynus forskahlii; and Annulotrema elongata Paperna and Thurston, 1969 from Alestes baremoze and Alestes dentex. A. elongata is re-described on the basis of new material from A. baremoze. The sclerotized structures of the haptor and male copulatory organ of A. alestesnursi and A. elongata are illustrated from their type material. H. forskahlii is a new host record for A. besalis. The findings of A. besalis and A. elongata in Kenya represent a new locality records for these helminths. Three Annulotrema spp., namely A. besalis, A. elongata and A. pontile n. sp., share the same type of male copulatory organ, which may indicate a close relationship among these species.

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

Two new and one known species of Annulotrema Paperna & Thurston, 1969 are reported from the gills of the tigerfish Hydrocynus vittatus Castelnau, 1861, collected in Lake Kariba, Zimbabwe. The new species, Annulotrema pseudonili n. sp. and A. bracteatum n. sp., are described and distinguished mainly on the basis of features of the male copulatory organ (MCO). Annulotrema pseudonili n. sp. most closely resembles A. nili Paperna, 1973, but differs from it by possessing a more delicate MCO with a thin-walled base without a fibrous distal part. Annulotrema bracteatum n. sp. is most similar to Annulotrema ruahae Paperna, 1973, from which it differs by having an MCO composed of a longer copulatory tube and a leaf-shaped accessory piece enveloping the distal part of the tube. The presence of Annulotrema pikoides Guégan, Lambert & Birgi, 1988 on H. vittatus in Zimbabwe represents a new locality record for this parasite.

Objectifs: Ce travail vise a faire le premier inventaire qualitatif et quantitatif du peuplement ichtyologique du lac de barrage d’Ayame 2. Methodologie et resultats: L’ichtyofaune a ete echantillonnee mensuellement entre Juin 2015 et Mai 2016 au moyen des filets maillants. Les donnees des peches experimentales ont ete completees par celles des peches commerciales. Au total, 40 especes de poissons incluant un Tilapia hybride ( T. zillii x T. guineensis ) et deux especes introduites ( Oreochromis niloticus et Heterotis niloticus ) ont ete recoltees. Ces especes sont reparties en 26 genres et 15 familles. Le peuplement ichtyologique est domine par les Cichlidae (35,04%), Claroteidae (28,89%) et Alestidae (24,91%). Les especes majoritaires sont Oreochromis niloticus (30,99%), Chrysichthys nigrodigitatus (17,9%) et Brycinus nurse (11,74%). Les valeurs des indices de diversite traduisent que le peuplement du milieu est diversifie. Conclusion et application des resultats: Cette etude a permis de faire le premier inventaire qualitatif et quantitatif de l’ichtyofaune du lac de barrage d’Ayame 2. Ces resultats serviront de references pour les investigations ulterieures de suivi de la faune ichtyologique et a l’elaboration de mesures adequates pour assurer une meilleure protection et une exploitation durable des ressources aquatiques de ce lac. Mots cles: Poisson, inventaire, diversite, lac de barrage d’Ayame 2, Cote d’Ivoire English Title: Preliminary data on the ichtyofauna of a west African Lake situated between two hydroelectric dams: man-made Lake Ayame 2 (Cote d’Ivoire) English Abstract Objectives: The objective of this work is to study for the first time the composition of fishes in the man-made Lake Ayame 2 situated between two hydroelectric dams. Methodology and Results: The ichthyofauna of man-made Lake Ayame 2 (South eastern of Cote d’Ivoire) was collected between June 2015 and May 2016. Fish samples were collected using gill-nets and commercial fish landings and held workshop with the local fishermen. Forty (40) species were identified in this study. The family of Cichlidae (35.04%), Claroteidae (28.89%) and Alestidae (24.91%) were dominated the fish community of man-made Lake Ayame 2. The most abundant species were Oreochromis niloticus (30.99%), Chrysichthys nigrodigitatus (17.9%) and Brycinus nurse (11.74%). The values of diversity index show that the population of environment is diversified. Conclusion and application of findings: This study allowed to make an inventory of the ichthyofauna of manmade Lake Ayame 2 for the first time and to characterize the population. These results will be references to follow through ichthyofauna and to take appropriate steps to avoid losses in aquatic biodiversity. Keywords: Fish, inventory, diversity, man-made Lake Ayame 2, Cote d’Ivoire

This study revises the originally monotypic genus Afrogyrodactylus Paperna, 1968 (Monogenea), the species of which infect alestid fish (Characiformes) in Africa, and includes new records of these parasites from three geographically distant countries, Senegal, Sudan and South Africa. Morphology of opisthaptoral hooks and bars and nuclear ribosomal DNA data revealed three Afrogyrodactylus species. Afrogyrodactylus girgifae sp. n. is described from the fins of the Sudanese nurse tetra, Brycinus nurse (Ruppell), and A. kingi sp. n. presents from the gill arches of the South African sharptooth tetra, Micralestes acutidens (Peters), whereas a previously undescribed Afrogyrodactylus sp. occurred on the fins of B. nurse from Senegal. All three species differ conspicuously from the only one known species of this genus, A. characinis Paperna, 1968, by the dimensions of their haptoral hard parts. Detailed morphological and molecular descriptions and comparisons are presented.

Human pressures and loss of natural fish habitats led to a decline in fish populations in terms of abundances, biodiversity, and average size in sub-Sahelian Burkina Faso. Little knowledge exists about fish assemblages regarding their composition, their habitat preferences, or their sensitivity to or tolerance of human pressures. This research provides the first data-driven basis for sustainably managing fish and associated aquatic and terrestrial habitats. Surveys in four different regions sampled 18,000 specimens from 69 species during the dry season. Fish communities, available abiotic habitat conditions, habitat use, and human pressures were assessed and analyzed. Fish communities cluster into four distinct types, each dominated by either Cichlidae, Clariidae, Cyprinidae, or Alestidae and accompanied by specific other families and genera of fish. Habitat preferences of four key species (Labeo coubie, Bagrus bajad, Chelaethiops bibie, and Lates niloticus) were linked to ecological habitat conditions. Results show that physical parameters influence fish community composition and abundances and, when indexed according to pressure type, are linked to responses in fish metrics. Relative abundance either dropped (Mormyridae) or increased (Cichlidae, Cyprinidae) with rising pressure intensity, and some sentinel taxa (Auchenoglanis, Hydrocynus) were only found in low-pressure sites. The outcomes of this study provide basic knowledge of habitat availability, habitat use by fish, species associations, and human pressures and therefore provide the basis for effective conservation and management of fish populations.

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

Human induced habitat destruction and modifications cause losses of aquatic and terrestrial biodiversity. The Congo and its islands constitute special ecosystems and have been used by humans for many purposes over centuries. However, little is known about the effects of these human activities on the fish species richness and distribution. This study is a preliminary assessment of island habitat types, fish species richness and effects of human activities on fish distribution. Islands were randomly selected to describe island habitats, to collect fish specimens using nets and to record human activities, including agriculture. Terra firma island habitats were mostly mixed mature forest with clay and muddy substrates. We captured 29 fish morphotypes (13 families). Clariidae and Cyprinidae were widely distributed whereas Alestidae, Chanidae, Malapteridae and Polypteridae were restricted in their distribution. Humans permanently settled 76 % of the islands and 70 % were cultivated. Permanent human settlements and agriculture were related to erosion on ~50 % of islands. For reasons that are difficult to explain at this stage, fish morphotype richness decreased with increasing field sizes, warranting further investigations.

Renewed research at the early Miocene fossil site of Bukwa in northeastern Uganda has resulted in new fossil finds, including fish, with representatives of two families, Cichlidae and Alestidae. Although the two families were previously briefly reported from Bukwa, we here give a more detailed account of the fishes based on newly collected material. The cichlid material, mainly composed of vertebrae, can be tentatively assigned to one or more species of Pseudocrenilabrinae. The alestid material, comprising a diversity of teeth, likely represents several different species of Alestes, Brycinus, and/or Bryconaethiops. Although the ichthyofaunal diversity of Bukwa is low, the fishes are important for indicating the paleoenvironment and hydrographic connections of Bukwa. The early Miocene was a critical time for African faunas, because it was during this time that the Afro-Arabian and Eurasian plates came into contact with one another, ending the long isolation of Africa, which, along with rifting in E...

A new species of Bathyaethiops is described from the Lekoumou River in the Kouilou–Nairi basin of the Republic of Congo. Bathyaethiops atercrinis, new species, is distinguished from its three central African congeners in the possession of 21–24 scales in longitudinal series vs. 28–42 scales, and from Brachypetersius altus by the possession of a short, abridged lateral line consisting of only six or seven pored scales vs. a complete lateral line of 20–28 pored scales. The species is unique among congeners and related taxa in displaying marked sexual dichromatism and dimorphism of the supporting skeleton of the anal fin. The presence of B. atercrinis in the Lekoumou represents the first record of the genus in the Lower Guinean ichthyofaunal province and the first occurrence outside of the Congo basin.

Micralestes eburneensis Daget 1965, an endemic characin fish of Ivory Coast / Liberia is assessed as Near Threatened due to its restricted range. In addition, there is strong fishing pressure, habitat loss and aquatic pollution from clandestine gold mining in the Cavally River bed.Moreover, given the development and intensification of mining activities in the study area, it is to be expected that the population of the endemic species will continue to decline. The strong anthropogenic pressure in this region on the Cavally hydrosystem and its environment must be taken into account for a future update of M. eburneensis conservation status.There is an immediate need for developing protection and management actions for this fish species.

A collection of fossil fish teeth and other elements from Eocene deposits on the northshore of Birket Qarun, Fayum Depression, Egypt, is reported. This collection adds significantly to our knowledge, as it consists of material that was screened from the sediments, allowing collection of small teeth that represent taxa not previously reported from the Fayum. Previous collections from these sediments have concentrated on larger remains that generally represent elasmobranchs, which are marine species from deposits lower in the section. Most of this material, collected by screening at the Birket Qarun 2 (BQ-2) locality, represents fully freshwater fishes. It includes the first record of the mormyrid Gymnarchus in the Fayum Depression, which represents the oldest record for this group, known previously only from the late Miocene or younger deposits. Similarly, Mochokidae (Siluriformes) and Hydrocynus (Alestidae) remains from the site are the oldest record of these taxa. Other taxa recovered are the os...

To ensure the utilisation of optimal tigerfish gene pools for artificial propagation, the hypothesis that tigerfish from the Okavango system should have greater heterozygosity than those from smaller river systems was tested. This electrophoretic analysis provides the first report of the quantity and pattern of genetic variation for tigerfish of the Okavango Delta to be considered for artificial propagation and as candidates for an evolutionary significant unit. Mean heterozygosity was 1% in the Okavango, as compared to 1.9% in the Upper Zambezi and 5.6% in the Olifants River systems. Possible reasons for this anomaly, in terms of the Hardy-Weinberg principle, include the founder effect caused when the Okavango and Zambezi rivers became separated, and/or that the Okavango is a more stable system and therefore that a large variation might not be required in its individuals for survival. Significant differences of genotypes were found among all populations previously studied. The selection of potential cand...

The following four species (only females available) of the Philometridae (Nematoda: Dracunculoidea) were recorded from freshwater fishes of Lake Turkana, northwestern Kenya in 2007-2008: Philometra bagri (Khalil, 1965) from the subcutaneous tissue around the mouth, on gill covers and the fin base of the bayad Bagrus bajad (Forsskål) (Bagridae: Siluriformes), Philometra lati sp. n. from the abdominal cavity of the Nile perch Lates niloticus (Linnaeus) (Latidae: Perciformes), Philometra spiriformis sp. n. from capsules on the inner surface of gill covers of L. niloticus and Afrophilometra hydrocyoni (Fahmy, Mandour et El-Nafar, 1976) comb. n. from the fins of Hydrocynus forskahlii (Cuvier) (Alestidae: Characiformes). The new species P. lati is characterized mainly by the presence of distinct oesophageal teeth, absence of large cephalic lobes and caudal projections, and by a combination of other features. Philometra spiriformis differs from all congeners principally in the spirally coiled body and from individual species by a combination of other morphological features. The already known species P. bagri and A. hydrocyoni are redescribed based on light and scanning electron microscopy; findings of both these species in Kenya represent new geographical records.

A new species of Alestes from the Mpozo River in the Bas Congo Province of the Democratic Republic of Congo is described and diagnostic characters for the genus are presented. Alestes inferus, new species, is differentiated from all other members of the genus by its lower and non-overlapping lateral-line scale count (31–33 versus 36–51) and its reduced and non-overlapping vertebral count (39–40 versus 41–49). Within Alestes, the new species appears to be most closely related to A. macrophthalmus and A. liebrechtsii, based on the shared possession by these three species of a tubular, bony extension enclosing the olfactory nerve on the lateral ethmoid, and bifurcated lateral-line canals terminating in two pores. Alestes liebrechtsii and A. inferus are the only species of the genus known from the lower Congo River.

Ultrastructural studies of spermiogenesis in Phenacogrammus interruptus using transmission electron microscopy revealed that the process is characterized by flagellum development, formation of a cytoplasmic canal, nuclear rotation, and nuclear fossa formation. Chromatin compaction proceeds during spermatid transformation within the spermatocysts as well as after spermiation within the lumen of the efferent ducts. The spermatozoon is of primitive type and exhibits characters typical for Type I aquasperm. The head consists of a spherical nucleus with highly condensed chromatin and a centrally located electron lucent area connected to a moderate-sized nuclear fossa. The nuclear fossa contain centrioles in perpendicular arrangement, surrounded by osmiophilic fibrous material. In the short midpiece, several mitochondria and vesicles are unevenly distributed in the cytoplasm forming the cytoplasmic collar at the base of the nucleus. The cytoplasmic collar surrounds the initial part of the flagellum, running in the cytoplasmic canal. The flagellar axoneme has a typical pattern (9 x 2 + 2) and the flagellum contains membranous compartments in the portion immediately posterior to the termination of the cytoplasmic canal.

Snorkelling surveys using a point abundance method revealed high levels of microhabitat differentiation among 14 fish species from a high-visibility site in the middle reaches of the Gambia River. Habitat segregation was most strongly related to the position in the water column, flow velocity, substratum composition and presence of submerged wood.

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

A new dwarf alestid from the vicinity of Inga on the lower Congo River, Bas Congo Province, Democratic Republic of Congo is described. Assignment of the new taxon to the poorly defined genus, Micralestes, is discussed and justified on the basis of available morphological character data. With the recognition of Micralestes schelly sp. nov., a total of six Micralestes are now known to inhabit the 350 km stretch of the Congo River from Pool Malebo to Boma near the river’s estuary. These are Micralestes acutidens (Peters, 1852), Micralestes humilis Boulenger, 1899, Micralestes lualabae Poll, 1967, Micralestes holargyreus (Günther, 1873), Micralestes stormsi Boulenger, 1902, and the new species Micralestes schelly. Of these Micralestes schelly and Micralestes holargyreus are considered herein as restricted-range endemics of the lower Congo River. An illustrated key to Micralestes of the lower Congo River is provided.

The current study explores information on fish diversity and fishing gears used in Tomas Dam Danbatta, Kano State and Daberam Dam Daura, Katsina State. From the results 5 different species belonging to 3 families were found in Tomas dam, and these are; Tilapia zilli, Oreochromis niloticus and Sarotherodon galilaeus belonging to the Family Cichlidae, Clarias gariepinus from the Family Claridae and Lates niloticus from the Family Centropomidae. Whereas in Daberam Dam, 6 species belonging to 5 families were observed and these are: Oreochromis niloticus, Hemichromis bimaculatus (Family Cichlidae), Clarias gariepinus (Family Claridae) and Eutropius niloticus, Hyperopiss bebe and Alestes beramoze from the Family Shilbeidae, Mormyridae and Alestidae respectively. The research also revealed that, Cichlidae were the most dominant fish type in these two Dams with Oreochromis niloticus leading specie in Tomas dam, with 61% percentage abundance, while Hemichromis bimaculatus is the most abundant species in Daberam Dam having 85% percentage abundance. The types of fishing gears used in both Tomas and Daberam Dam are similar with triggered trap dominating the fishing site in each dam. Keywords: Cast net, Daberam Dam, Hooks, Line net, Tomas Dam, Triggered trap.

The overall most parsimonious hypothesis of relationships based on 200 characters indicates that the Alestidae is the closest relative of Chalceus, a genus previously assigned to the Neotropical Characidae. Chalceus is shifted into the Alestidae, which becomes the only trans-Atlantic family level group within the Characiformes. Various previously proposed suprageneric assemblages within the Alestidae (e.g. Petersiini) failed to delimit monophyletic groups under the intrafamilial phylogenetic analysis. The evaluation of fossil alestids within the context of the phylogeny indicates that the ancestors of Alestes, Arnoldichthys, Brycinus, Bryconaethiops and Hydrocynus evolved prior to the early Eocene (Cuisian of Upper Ypresian), 49–54.8 million years ago, with the fossil Alestoides most closely related to Alestes. The phylogenetic information further indicates a minimum age of 90–112 million years for the Alestidae. Contrary to previous hypotheses, the fossil African Sindacharax was found to be most similar to the clade including the alestid genus Bryconaethiops rather than most closely related to the South American subfamily Serrasalminae. Evaluation of the fossil Mahengecharax carrolli fails to support its hypothesized placement as the sister group to all Recent members of the Alestidae. Two separate episodes of miniaturization and one episode of gigantism occurred within the evolution of the Alestidae. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 1−144. No claim to original US government works.

The African family Alestidae (Ostariophysii: Characiformes) includes today 13 genera, among which seven are monospecific. The size range observed in the family greatly varies with species ranging from 21 mm up to 130 cm for more than 50 kg. Among the Alestidae, three tribes were previously identified: the Alestini, the Hydrocinini and the Petersiini, that include all the miniaturised species. Previous phylogenetic studies mainly focussed on the relationships between the genera Alestes, Brycinus, Bryconaethiops and Hydrocynus and left the phylogenetic affinities of the genera from the tribe Petersiini unexplored. We assessed the molecular phylogenetic relationships within the family using partial mitochondrial ribosomal DNA sequences of the 12S and 16S genes and evaluated the congruence with available morphological characters by separate and combined analyses. We especially focussed on the phylogenetic status of the tribe Petersiini and further investigated the early divergence among the family. Our results lead to the identification of two major lineages and to the description of three new clades. The relationships inferred allowed us to reject monophyly of the genera Brycinus, Micralestes and Rhabdalestes and to suggest that the genus Bryconaethiops should be removed from the tribe Alestini. We also have shown that miniaturization occurred more than once, contrary to the predictions of the present classification.

The osteology of a population of the characiform fish Alestes stuhlmannii, from the Rufiji River basin of Tanzania, is described, and meristic and morphometric data from over 100 specimens, ranging from 15.5 to 218 mm standard length are given. Two allometric changes occur during growth of this fish: both the number of gill rakers and the interorbital width relative to the head length increase with size. There are also changes in tooth form associated with growth in A. stuhlmannii, with the unicuspid teeth of juveniles becoming almost molariform in adults. This change in dentition with age, and therefore size, may have implications for recognizing taxa, some of which (the fossil genera Sindacharax and Bunocharax, and the living dwarf petersiines) have been distinguished by jaw or dental characters.

A single specimen of the anterior portion of a small fish was collected from the Eocene Mahenge site of Tanzania in 1996. The specimen, preserved as part and counterpart natural mold, is identified as belonging to a characiform fish, although the presence of a Weberian apparatus has not been confirmed beyond doubt. Features of the bones, such as the prominent lateral ridge on the anterodorsal corner of the opercle, the fused postcleithra 2+3, and the lack of a dentary symphyseal hinge, indicate that the fish is related to the Citharinidae and Distichodontidae. The fossil cannot be included in any known genus, and is described here as a new genus and species, Eocitharinus macrognathus. The fossil record of characiforms includes few articulated skeletons, of which only one had been reported previously from Africa, described in the family Characidae (=Alestidae).

Four specimens of a small fossil fish were collected from the Eocene Mahenge site of Tanzania. The specimens, preserved as part and counterpart natural moulds, are identified, predominantly based on the structure of the caudal skeleton, as members of the Characiformes, probably the sister group to the living African Alestidae. The area just behind the skull, in the two specimens that include this area, is distorted, and therefore it is difficult to identify the bones of the Weberian apparatus, although that structure does appear to be present. The fossil record of characiforms includes few articulated skeletons, with only one other African species previously reported from much younger deposits. The new specimens from Mahenge are described here as a new genus and species, Mahengecharax carrolli.

The family Alestidae (also referred to as the African Characidae) comprises the African dwarf forms ("Petersiini") and the genera Alestes, Brycinus, Bryconaethiops, and Hydrocynus. Although several authors have presented characters to support the monophyly of the family, a cladistic analysis of the group has not been published. Furthermore, the interrelationships of the constituent groups are the subject of some controversy. A cladistic analysis of the Alestidae is presented, including characters to support the monophyly of the family. The results of this study indicate that several species should be removed from the genus Brycinus, that Hydrocynus is the sister group of Alestes s.str. (containing only five species), and that the dwarf alestids ("Petersiini") do not form a monophyletic group.

Made available in DSpace on 2015-02-02T12:39:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-04-01Bitstream added on 2015-02-02T13:08:27Z : No. of bitstreams: 1 S1679-62252014000200419.pdf: 6936041 bytes, checksum: ff695abb2ca2a3eba28c5f0d9df7fe7b (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A espermiogênese e os espermatozoides de seis gêneros que compõem a família Alestidae mais o gênero Chalceus são descritos. A espermiogênese é muito similar em todas as espécies de Alestidae analisadas e pode ser considerada como sendo o Tipo I e suas variações. Neste tipo de espermiogênese, o flagelo das espermátides iniciais dispõe-se lateral ao núcleo. A rotação do núcleo em direção ao complexo centriolar está presente. A rotação nuclear é completa, atingindo 90 graus, em Bryconalestes longipinnis, Brachypetersius altus, Brycinus imberi, B. lateralis e Alestopetersius compressus; incompleta, atingindo 20 graus, em Micralestes acutidens e Rhabdalestes rhodesiensis. A morfologia dos espermatozoides de Alestidae varia desde o núcleo medial com cromatina fibrilar no gênero Brycinus, considerado mais basal, até o núcleo muito excêntrico com cromatina altamente compactada, nos gêneros Rhabdalestes e Micralestes, considerados mais derivados dentro de Alestidae. Chalceus possui um espermatozoide muito similar a Brycinus, compartilhando entre eles o aspecto fibrilar da cromatina no núcleo. Esta característica até o momento só foi observada nestes dois gêneros dentre os Characiformes Africanos e Neotropicais. Spermiogenesis and spermatozoa in six genera of the African family Alestidae plus the Neotropical genus Chalceus are described. Spermiogenesis is quite similar in all Alestidae and is identified as Type I and its variants. In Type I spermiogenesis, the flagellum of earliest spermatids lies lateral to the nucleus, and rotation of the nucleus towards the centriolar complex is observed. Nuclear rotation is complete reaching 90 degrees in Bryconalestes longipinnis, Brachypetersius altus, Brycinus imberi, B. lateralis, and Alestopetersius compressus; and is incomplete reaching 20 degrees in Micralestes acutidens and Rhabdalestes rhodesiensis. Spermatozoa morphology varies from a medial nucleus with fibrillar chromatin in the most basal genus Brycinus to a strongly eccentric nucleus with highly condensed chromatin in the more derived Rhabdalestes and Micralestes. Chalceus has a very similar spermatozoon to that found in Brycinus sharing the fibrillar aspect of the chromatin in the nucleus. This feature is so far only observed in these two genera among African and Neotropical characiform fishes. Universidade Estadual de Campinas Programa de Pós-Graduação em Biologia Celular e Estrutural Universidade de São Paulo Instituto de Biociências Departamento de Genética e Biologia Evolutiva Universidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências Departamento de Morfologia Universidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências Departamento de Morfologia

Two new species of Annulotrema Paperna & Thurston, 1969 were collected from the gills of the African tiger fish, Hydrocynus brevis, from the Gambia River basin in the Niokolo-Koba National Park, Senegal. Annulotrema besalis n. sp. is characterized by having a male copulatory organ (MCO) composed of an arcuate copulatory tube articulated to an eight-shaped accessory piece with terminal claw. The new species resembles Annulotrema pikei (Price, Peebles & Bamford, 1969) in having morphologically similar types of haptoral sclerites and MCO. As a result of the differential diagnosis made for A. besalis n. sp., new information on taxonomically important features of A. pikei is provided based on illustrations of the sclerotized parts of the holotype from Hydrocynus vittatus. The report of A. pikei on the gills of Hydrocynus forskahlii by Paperna in 1979 is shown to be erroneous. Annulotrema uncata n. sp. is similar to Annulotrema alestesimberi Paperna, 1973 in its possession of a coiled copulatory tube with about two and a half rings. Features distinguishing the new species include the sharply curved shaft of the ventral anchor, the base of the copulatory tube extending to a sock-like structure and a leech-shaped vagina. The necessity of emending the generic diagnosis of Annulotrema is briefly discussed.

Fishes of the order Characiformes are a diverse and economically important teleost clade whose extant members are found exclusively in African and Neotropical freshwaters. Although their transatlantic distribution has been primarily attributed to the Early Cretaceous fragmentation of western Gondwana, vicariance has not been tested with temporal information beyond that contained in their fragmentary fossil record and a recent time-scaled phylogeny focused on the African family Alestidae. Because members of the suborder Citharinoidei constitute the sister lineage to the entire remaining Afro-Neotropical characiform radiation, we inferred a time-calibrated molecular phylogeny of citharinoids using a popular Bayesian approach to molecular dating in order to assess the adequacy of current vicariance hypotheses and shed light on the early biogeographic history of characiform fishes. Given that the only comprehensive phylogenetic treatment of the Citharinoidei has been a morphology-based analysis published over three decades ago, the present study also provided an opportunity to further investigate citharinoid relationships and update the evolutionary framework that has laid the foundations for the current classification of the group. The inferred chronogram is robust to changes in calibration priors and suggests that the origins of citharinoids date back to the Turonian (ca 90 Ma) of the Late Cretaceous. Most modern citharinoid genera, however, appear to have originated and diversified much more recently, mainly during the Miocene. By reconciling molecular-clock- with fossil-based estimates for the origins of the Characiformes, our results provide further support for the hypothesis that attributes the disjunct distribution of the order to the opening of the South Atlantic Ocean. The striking overlap in tempo of diversification and biogeographic patterns between citharinoids and the African-endemic family Alestidae suggests that their evolutionary histories could have been strongly and similarly influenced by Miocene geotectonic events that modified the landscape and produced the drainage pattern of Central Africa seen today.

Alestidae is a clade of African characiform fishes including 19 extant genera and approximately 105 species that are known from Afro-Arabia, with records reported from the Eocene-Oligocene Jebel Qatrani Formation of Egypt, the Eocene Mahenge crater lake of Tanzania, and early Oligocene to Miocene sites on the Arabian Plate. Here we report the first record of alestid fishes from the late Oligocene Nsungwe Formation in the Rukwa Rift Basin of southwestern Tanzania. The Nsungwe alestid sample is composed of 92 teeth spanning a range of sizes and morphologies. Teeth are examined with regard to cusp number and organization, tooth position and replacement, and in the context of alestid jaw organization using modern, comparative representatives. Results suggest that at least two alestid taxa are represented in Nsungwe Formation localities. Hydrocynus teeth exhibit a single, conical cusp. Several of these specimens preserve a mesiodistally expanded crown and concave surface on the lingual aspect of the t...

Two new species of Bathyaethiops (Teleostei: Characiformes: Alestidae) are described. Bathyaethiops baka n. sp. is a dwarf species with the largest known specimen being only 24.4 mm SL. The species is characterized by an incomplete squamation and a large humeral spot. Bathyaethiops baka n. sp. is known so far only from the Ngoko River of Southeastern Cameroon, a tributary of the Sangha River in the northern Congo basin. The second species, Bathyaethiops flammeus n. sp., shows a diagnostic spot in front of the dorsal-fin base, which is devoid of melanophores and bright red in life. The species is described from the Bakere River at Yambula-Bakere, a locality north-west of Kisangani in the Central Congo basin. Other records of Bathyaethiops flammeus n. sp. from the Tshuapa respectively Ruki River at Boende and Eala, Central Congo basin, suggests a wider geographic distribution. A key to all species of Bathyaethiops is provided.

A new Alestopetersius is described from the Kwilu River in the Kasai basin of the Democratic Republic of Congo. Alesto- petersius conspectus, new species, is readily distinguished from all congeners based on attributes of squamation and col-oration. It is distinguished from “Duboisialestes” tumbensis by tooth morphology and in the possession of a distinctivecaudal-fin pigmentation patterning consisting of a median black band extending to the caudal-fin margin and flanked bydense black bands in both upper and lower fin lobes. “Duboisialestes” bifasciatus, which shares similar caudal-fin pig-mentation patterning, is distinguished from A. conspectus by the absence of a broad mid-lateral band on the body, and bytooth morphology. Results from an analysis of the relationships and generic composition of the Alestidae provide supportfor the monophyly for Alestopetersius inclusive of the members of the genus Duboisialestes, which are placed into syn-onomy with the former.Une nouvelle espece de Alestopetersius est decrite de la riviere Kwilu dans le bassin du Kasai de la RepubliqueDemocratique du Congo. Alestopetersius conspectus, nouvelle espece, se distingue tres facilement de tout ses congeneressur les attributs de la squamation et coloration. Cette espece est distinguee de “Duboisialestes” tumbensis par la morphol-ogie des dents et par la possession d'un type de pigmentation de la nageoire caudale composee d’une bande noire medianes'etendant de la marge de la caudale et flanquee de denses bandes noires dans les deux lobes superieur et inferieur de lanageoire. “Duboisialestes” bifasciatus qui partage le meme type de pigmentation de la nageoire caudale, se distingue de A. conspectus par l'absence d'une large bande mi-laterale sur le corps, et par la morphologie des dents. Les resultats d'uneanalyse des relations et de la composition generique du Alestidae fournissent un soutien pour la monophylie des Alestopetersius incluant les membres du genre Duboisialestes, qui sont places en synonymie avec le genre precedent.

The Characiformes are distributed throughout large portions of the freshwaters of Africa and America. About 90% of the almost 2000 characiform species inhabit the American rivers, with their greatest diversity occurring in the Neotropical region. As in most other groups of fishes, the current knowledge about characiform myology is extremely poor. This study presents the results of a survey of the mandibular, hyopalatine, and opercular musculature of 65 species representing all the 18 traditionally recognized characiform families, including the 14 subfamilies and several genera incertae sedis of the Characidae, the most speciose family of the order. The morphological variation of these muscles across the order is documented in detail and the homologies of the characiform adductor mandibulae divisions are clarified. Accordingly, the mistaken nomenclature previously applied to these divisions in some characiform taxa is herein corrected. Contradicting some previous studies, we found that none of the examined characiforms lacks an A3 section of the adductor mandibulae, but instead some taxa have an A3 continuous with A2. Derived myological features are identified as new putative synapomorphies for: the Characoidei; the clade composed of the Alestidae, Characidae, Gasteropelecidae, Cynodontoidea, and Erythrinoidea; the clade Cynodontoidea plus Erythrinoidea; the clade formed by Ctenoluciidae and Erythrinidae; the Serrasalminae; and the Triportheinae. Additionally, new myological data seems to indicate that the Agoniatinae might be more closely related to cynodontoids and erythrinoids than to other characids.

Background. Despite the importance of Lake Tanganyika's biodiversity for science and the livelihoods of the riparian people, high-resolution surveys of the fish biodiversity are sparse and fragmentary, especially along the western (Congolese) shoreline. The coast suffers locally from intensive human activities and lacks adequate protective measures or nature reserves. However, in view of the intra-lacustrine endemism of this fish fauna, conservation needs to be managed lake-wide at a fine scale, necessitating detailed inventories on fish species distribution. The study aims at updating knowledge on fish diversity and distribution along the north-western and central western shores of Lake Tanganyika. Materials and methods. Fish specimens were collected using gill-and seine nets, by snorkelling and SCUBA diving, and through purchases on the local markets. Results. Over 28 locations were sampled, and 84 cichlid- and 30 non-cichlid fish species (belonging to Protopteridae, Clupeidae, Cyprinidae, Alestidae, Claroteidae, Clariidae, Malapteruridae, Mochokidae, Poeciliidae, Latidae, and Mastacembelidae) collected. Conclusion. Our records substantially expand the known range of fish species in a range of habitats. As numerous specimens are hard to assign to nominal species, a taxonomic revision of a number of genera is underway. It should take into account intraspecific geographic variation.

Phylogenetic relationships within the family Alestidae were investigated using parsimony, maximum likelihood, and Bayesian approaches based on a molecular dataset that included both nuclear and mitochondrial markers. Multiple representatives of all but two of the recognized alestid genera were included, which allowed for testing previous hypotheses of intergeneric relationships and the monophyly of several genera. The phylogenetic position of the Neotropical genus Chalceus with respect to the family Alestidae was also examined. In order to understand the temporal context of alestid diversification, Bayesian methods of divergence time estimation using fossil data in the form of calibration priors were used to date the nodes of the phylogenetic tree. Our results rejected the monophyly of the family as currently recognized (Alestidae sensu lato) and revealed several instances of poly- and paraphyly among genera. The genus Chalceus was recovered well nested within Neotropical characiforms, thus rejecting the hypothesis that this taxon is the most basal alestid. The estimated mean divergence time for the alestid clade (Alestidae sensu stricto) was 54 Mya with a 95% credibility interval of 63-49 Mya. These results are incongruent with the hypothesis that the origin of the family Alestidae predates the African-South American Drift-Vicariance event.