1,720,971 research outputs found
Description of five new rheophilic Orthochromis species (Teleostei: Cichlidae) from the Upper Congo drainage in Zambia and the Democratic Republic of the Congo
No full textSchedel, Frederic Dieter Benedikt, Vreven, Emmanuel J.W.M.N., Manda, Bauchet Katemo, Abwe, Emmanuel, Manda, Auguste Chocha, Schliewen, Ulrich Kurt (2018): Description of five new rheophilic Orthochromis species (Teleostei: Cichlidae) from the Upper Congo drainage in Zambia and the Democratic Republic of the Congo. Zootaxa 4461 (3): 301-349, DOI: 10.11646/zootaxa.4461.3.
Comparative population mitogenomics of fish parasites reveals contrasting geographic pattern in the pelagic zone of Lake Tanganyika
No full textAfrican Great Lakes and their fauna are among the prime model systems for evolutionary research. Lake Tanganyika is the second deepest lake in the world and its permanently stratified, relatively species-poor and well-delimited pelagic zone offers a simple model for ecosystem dynamics of open water areas worldwide. In our study, we focused on mitogenomic differentiation of directly transmitted parasites (Monogenea, Kapentagyrus) infecting two species of pelagic clupeid fishes across two subbasins of Lake Tanganyika, to unravel patterns of migration and population dynamics in the pelagic zone of large water bodies. Starting from pooled population samples, altogether containing more than 800 specimens, we provide the first population-genomic study on any parasite in the African Great Lakes. Our results indicate a lack of spatial population structuring in Kapentagyrus tanganicanus infecting its two clupeid hosts. In Kapentagyrus limnotrissae, a parasite specific to only one of the two clupeid hosts, spatial and seasonal restriction in gene flow are observed. Contrasting patterns in spatial population structuring between K. tanganicanus and K. limnotrissae reflect their differences in host range and in the life histories, migration and habitat preference of their respective hosts. This is a proof-of-concept of how parasites can be reliable tags for hardly traceable hosts, in this case indicating host and parasite connectivity throughout the hosts' spatial distribution. Comparison of population-genetic parameters based on individual specimens versus pooled samples proofs PoolSeq as a suitable method in (mito)genomics of minute taxa that are hard to access in the field
Diversity of Quadriacanthus (Monogenea: Dactylogyridae) in the Upper Congo Basin: new geographical records and description of five new species from the gills of Clarias ngamensis (Siluriformes: Clariidae)
No full textABSTRACT Monogenean parasites belonging to Quadriacanthus have never been reported from Clarias ngamensis, but are commonly found on congeners. In view of the specificity of monogeneans, the genetic proximity and the co-occurrence of C. ngamensis and C. gariepinus in Africa, it is hypothesised that a parasitological survey of C. ngamensis will yield several species of Quadriacanthus as its congeneric host C. gariepinus harbours these parasites. The present study aims to explore the monogenean parasites from the gills of C. ngamensis in the Upper Congo Basin by (i) inventorying their diversity and providing their morphological characterisation, and (ii) analysing their infection parameters. Monogeneans were isolated from the gills, and identified based on morphological analysis of genital and haptoral sclerotized parts. Seven parasite species belonging to Quadriacanthus were found. Among them, two species, Q. aegypticus and Q. allobychowskiella, are both newly reported in the Upper Congo Basin and newly recorded on C. ngamensis. Quadriacanthus amakaliae sp. nov., Q. halajiani sp. nov., Q. domatanai sp. nov., Q. lubandaensis sp. nov., and Q. curvicirrus sp. nov. are new to science and described herein. The most prevalent parasite species was Q. curvicirrus sp. nov. in the Luapula River (prevalence = 66.7%) with mean infection intensity of 6.3 ± 5.8. Quadriacanthus allobychowskiella and Q. aegypticus are known parasites from C. gariepinus and their presence on C. ngamensis is probably the result of lateral transfers. The discovery of five new species from C. ngamensis highlights the parasite diversity still to be explored in the region
New Records and Descriptions of Three New Species of Quadriacanthus (Monopisthocotyla: Dactylogyridae) from Catfishes (Teleostei: Siluriformes, Clariidae) in the Upper Congo Basin
No full textIn the Upper Congo Basin, there are few records of monopisthocotylan parasites from clariids. More surveys of clariid fishes can lead to the discovery of multiple monopisthocotylan species that are new to the region or new to science. We aimed to investigate the monopisthocotylan parasite fauna belonging to Quadriacanthus of five clariid fishes in the Upper Congo Basin by (i) inventorying the species composition and providing the description of new species when necessary, and (ii) analysing their infection parameters. Clarias ngamensis, C. stappersii, C. buthupogon, C. gariepinus and C. theodorae were purchased from fishermen in the Lufira, Lubumbashi and Kafubu rivers in the Upper Congo Basin. Monopisthocotylans were mounted on glass slides with ammonium picrate-glycerin for identification based on morphological analysis of genital and haptoral sclerotised parts. Eight species, namely Q. aegypticus, Q. allobychowskiella, Q. amakaliae, Q. domatanai, Q. halajiani, Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. are reported. The most prevalent parasite species was Q. amakaliae on C. stappersii (prevalence 60%) with a mean infection intensity of 9.8 +/- 7.7. We report C. stappersii and C. buthupogon as new hosts for species of Quadriacanthus as well as three new parasite species for science and new localities for the first five parasite species mentioned above. The new records and the description of Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. increase the knowledge of the diversity of monopisthocotylans in this region.Funding:
The network underlying this study arose thanks to funding from VLIR-UOS, namely the Short Training Initiative “Building an African network for sustainable management of aquatic biological resources supported by genetics and parasitology” (NKOI2016PR008) and the South Initiative “Renforcement des capacités locales pour une meilleure évaluation biologique des impacts miniers au Katanga (RD Congo) sur les poissons et leurs milieux aquatiques” (ZRDC2014MP084), and from the framework agreements of the Belgian Development Cooperation with the Royal Museum for Central Africa (Mbisa Congo project 2013–2018) and the Royal Belgian Institute of Natural Sciences (Capacities for Biodiversity and Sustainable Development program). This research was also supported by VLIR-UOS (IUC-UNILU, CD2021IUC04A104 and Global Minds). Maarten P.M. Vanhove was financed by the Special Research Fund of Hasselt University (BOF20TT06). Wilmien J. Luus-Powell and Willem J. Smit were supported by the South African Research Chairs Initiative of the Department of Science and Innovation and National Research Foundation of South Africa (Grant No. 101054). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments:
The Université de Lubumbashi is thanked through the Faculty of Agronomic Sciences (for facilitating and authorising sampling) and the local team of the Laboratory BEZHU (Unité de Recherche en Biodiversité et Exploitation durable des Zones Humides), Anicet Doma Tana, Clément Kalombo Kabalika for their help in fish sampling. The University of Yaoundé 1 (Cameroon) is also thanked through the Faculty of Sciences, Laboratory of Parasitology and Ecology (Etienne Bassock and Jonathan Mbondo) for hosting and helping Gyrhaiss K. Kasembele in the lab for parasite identification and drawing during his research visit. The authors gratefully acknowledge Antoine
Pariselle, Filip A.M. Volckaert, Ouafae Berrada-Rkhami, Abdelaziz Benhoussa, Tine Huyse, Isaure de Buron-Connors, Valentin N’Douba, Arnold R. Bitja Nyom, Jos Snoeks, Emmanuel J. Vreven, Virginie Bito, and Luc Janssens de Bisthoven, senior scientists in the aforementioned projects
Molecular footprint of parasite co-introduction with Nile tilapia in the Congo Basin
No full textAbstract Nile tilapia, one of the most popular aquaculture species worldwide, has been introduced into the Congo Basin several times. In previous morphological studies, we showed that some of the monogenean gill parasites were co-introduced with Nile tilapia and some spilled over to native Congolese cichlids. In this study, we investigated the co-introduced monogeneans of Nile tilapia genetically from three major parts of the Congo Basin; Upper, Middle and Lower Congo. We generated sequences of Congolese native and introduced monogeneans from native and introduced tilapias and evaluate their position in a phylogeny. Additionally, we generated sequences of the same species of monogeneans co-introduced with Nile tilapia in Madagascar and of a native population of Nile tilapia from Burundi. Our results confirm the co-introductions in the Congo. We found that co-introduced parasites are less genetically diverse than native ones, and that there was no geographical pattern between introduced populations. Furthermore, our COI haplotype networks suggest multiple introduction events of Nile tilapia into the Congo Basin. Additionally, we tested the barcoding gap and the performance of mitochondrial COI and nuclear ribosomal ITS-1, 28S and 18S markers. We found a significant intra/interspecific barcoding gap of 15% for COI, but none for the other markers. Our molecular results reveal that Cichlidogyrus halli, C. papernastrema, C. tiberianus, C. cirratus and C. zambezensis are in need of taxonomic revision.</p
Lifestyle and not density of fish hosts determines parasite distribution over time and space
No full textFirst record of monogenean fish parasites in the Upper Lufira basin (Democratic Republic of Congo): dactylogyrids and gyrodactylids infecting Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus (Teleostei: Cichlidae)
No full textBackground Monogenean parasites have never been formally reported on fish from the Lufira basin. Then it is hypothesised that multiple monogenean species are to be recorded that are new to the region. This study aimed to record the gill monogenean parasite fauna of three cichlid fish species in the Upper Lufira basin by inventorying their diversity (species composition) and analysing their infection parameters (prevalence, mean intensity and abundance). Methods Oreochromis mweruensis, Coptodon rendalli , and Serranochromis macrocephalus were selected for the study, given their economic value and their abundance in the Upper Lufira basin. Monogeneans were isolated from the gills and stomach, mounted on glass slides with either Hoyer’s medium or ammonium picrate-glycerin for further identification under a stereomicroscope, based on morphological analysis of genital and haptoral hard parts. Indices of diversity and infections parameters were calculated. Results A total of thirteen gill monogenean parasite species ( Cichlidogyrus dossoui, C. halli, C. karibae, C. mbirizei, C. papernastrema, C. quaestio, C. sclerosus, C. tiberianus, C. tilapiae, C. zambezensis, Scutogyrus gravivaginus, S . cf. bailloni and Gyrodactylus nyanzae ) and one stomach monogenean ( Enterogyrus malmbergi ) were reported. A species richness of S= 10 for O. mweruensis , S= 6 for C. rendalli and S= 2 for S. macrocephalus were recorded. Five parasite species were reported to be common amongst O. mweruensis and C. rendalli . The most prevalent parasite species were C. halli (P= 80.9%) on O. mweruensis, C. dossoui (P= 92.9%) on C. rendalli and C. karibae and C. zambezensis (both of which P = 9.1%) on S. macrocephalus with a respective mean infection intensity of 7.9 on O. mweruensis , 9.8 on C. rendalli and 5 and 15, respectively, on S. macrocephalus . Results of this study reported new host ranges for five parasites species ( C. quaestio, S . cf. bailloni, E. malmbergi on O. mweruensis, C. halli on C. rendalli and C. karibae on S. macrocephalus ) as well as new geographical records for three of them ( S . cf. bailloni, E. malmbergi, C. karibae ). Conclusions This study highlights the richness of monogenean communities in the Upper Lufira basin and is a starting point for future helminthological studies, e.g. on the use of fish parasites as indicators of anthropogenic impacts
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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