One-quarter of freshwater fauna threatened with extinction.

Freshwater ecosystems are highly biodiverse and important for livelihoods and economic development, but are under substantial stress. To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters. Consequently, data from predominantly terrestrial tetrapods are used to guide environmental policy and conservation prioritization, whereas recent proposals for target setting in freshwaters use abiotic factors.

Revision of Nannocharax luapulae Boulenger, 1915 (Characiformes: Distichodontidae) from the Upper Congo basin: Evidence for a species pair.

For many decades, Nannocharax luapulae has been considered to be widespread in the southern part of the Upper Congo basin. However, meristic, morphometric and cytochrome c oxidase subunit I (COI) barcoding evidence revealed that its geographical distribution is restricted to the Luapula-Moero basin. The populations of the Upper Lualaba are assigned to a new species, N.

First record of monogenean fish parasites in the Upper Lufira River Basin (Democratic Republic of Congo): dactylogyrids and gyrodactylids infesting Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus (Teleostei: Cichlidae).

Background: Monogenean parasites have never been formally reported on fishes from the Lufira River Basin. In this context, we decided to record the monogenean parasite fauna of three cichlid species found in the Upper Lufira River Basin for the first time by inventorizing their diversity (species composition) and analysing their infection parameters (prevalence, mean intensity and abundance).

Methods: The African cichlid fishes Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus were selected for the study, given their economic value and their abundance in the Upper Lufira River Basin.

Population genomics of introduced Nile tilapia Oreochromis niloticus (Linnaeus, 1758) in the Democratic Republic of the Congo: Repeated introductions since colonial times with multiple sources.

During colonial times, Nile tilapia Oreochromis niloticus (Linnaeus, 1758) was introduced into non-native parts of the Congo Basin (Democratic Republic of the Congo, DRC) for the first time. Currently, it is the most farmed cichlid in the DRC, and is present throughout the Congo Basin. Although Nile tilapia has been reported as an invasive species, documentation of historical introductions into this basin and its consequences are scant.

Association between Labeobarbus spp. (Teleostei: Cyprinidae) and environmental variables in the Luhoho basin (Eastern Congo River basin; DRC).

The African cyprinid genus Labeobarbus is characterized by a high polymorphism in mouth morphology. The association between four species of this genus (two chiselmouths, one rubberlip with a well-developed fleshy mental lobe on the lower jaw, i.e.

The synonymy of Haplochromis pharyngalis and Haplochromis petronius (Cichlidae).

Haplochromis pharyngalis and Haplochromis petronius, two endemic cichlids from the Lake Edward system (Uganda, Democratic Republic of the Congo), are very similar in general morphology but have been reported to differ in pharyngeal jaw morphology and distribution. This study analysed 51 morphometrics and various qualitative characteristics of 48 specimens from different localities. The morphological traits of both species strongly overlap, and differences in the pharyngeal jaw morphology correspond to a geographic morphocline.

Mitogenomic characterization and systematic placement of the Congo blind barb Caecobarbus geertsii (Cypriniformes: Cyprinidae).

This study presents the first complete mitochondrial genome (mitogenome) of Caecobarbus geertsii, the Congo blind barb, a cave-dwelling, CITES-protected, cyprinid fish endemic to the Lower Congo basin (DRC). The length of the circular mitogenome is 16,565 base pairs. The 13 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes are similar in position and direction to those of other members of the family Cyprinidae.

An annotated checklist of the fish fauna of the river systems draining the Kahuzi-Biega National Park (Upper Congo: Eastern DR Congo).

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.

Terrestrial contributions to Afrotropical aquatic food webs: The Congo River case.

Understanding the degree to which aquatic and terrestrial primary production fuel tropical aquatic food webs remains poorly understood, and quantifying the relative contributions of autochthonous and allochthonous inputs is methodologically challenging. Carbon and nitrogen stable isotope ratios ( C, N) can provide valuable insights about contributions of terrestrial resources and trophic position, respectively, but this approach has caveats when applied in typical complex natural food webs.Here, we used a combination of C, N, and H ( H) stable isotope measurements and Bayesian mixing models to estimate the contribution of terrestrial (allochthonous) and aquatic (autochthonous) inputs to fish and invertebrate communities in the Congo River (and some tributaries).

Similar ecology, different morphology: Three new species of oral-mollusc shellers from Lake Edward.

Lake Edward, East Africa, harbours a largely understudied assemblage of haplochromine cichlids that displays a range of adaptions to various specialised trophic niches. In this system, we discovered specimens of Haplochromis with morphologies similar to those of oral-mollusc shellers from Lake Victoria. These morphologies are characterised by short oral jaws with stout teeth that are used either to crush molluscs or to grab the soft bodies of snails and wrench them out of their shells.

Where ichthyofaunal provinces meet: the fish fauna of the Lake Edward system, East Africa.

Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non-Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region.

DNA barcoding fishes from the Congo and the Lower Guinean provinces: Assembling a reference library for poorly inventoried fauna.

The Congolese and Lower Guinean ichthyological provinces are understudied hotspots of the global fish diversity. Here, we barcoded 741 specimens from the Lower and Middle Congo River and from three major drainage basins of the Lower Guinean ichthyological province, Kouilou-Niari, Nyanga and Ogowe. We identified 194 morphospecies belonging to 82 genera and 25 families.

Six new dactylogyrid species (Platyhelminthes, Monogenea) from the gills of cichlids (Teleostei, Cichliformes) from the Lower Congo Basin.

The Lower Congo Basin is characterized by a mangrove-lined estuary at its mouth and, further upstream, by many hydrogeographical barriers such as rapids and narrow gorges. Five localities in the mangroves and four from (upstream) left bank tributaries or pools were sampled. On the gills of Coptodon tholloni, Coptodon rendalli, Hemichromis elongatus, Hemichromis stellifer and Tylochromis praecox, 17 species of parasites (Dactylogyridae & Gyrodactylidae, Monogenea) were found, eight of which are new to science.

Delineating species along shifting shorelines: (Teleostei, Cichlidae) from the southern subbasin of Lake Tanganyika.

Background: Species delineation is particularly challenging in taxa with substantial intra-specific variation. In systematic studies of fishes, meristics and linear measurements that describe shape are often used to delineate species. Yet, little is known about the taxonomic value of these two types of morphological characteristics.

, a new endemic cichlid from Lake Malawi (Teleostei, Cichlidae).

A new species of , , is described from Lake Malawi. So far, it has only been found at Jafua Bay, Mozambique. It can easily be distinguished from by its molariform pharyngeal dentition.

Limited possibilities for prezygotic barriers in the reproductive behaviour of sympatric Ophthalmotilapia species (Teleostei, Cichlidae).

Since prezygotic rather than postzygotic barriers are believed to maintain the diversity of closely related sympatric cichlids, differences in phenotypic traits and reproductive behaviours are likely involved in maintaining species boundaries. Here, we focused on the reproductive behaviour of three Ophthalmotilapia species with distributions that only overlap on a small stretch of the shore line of Lake Tanganyika. Repeated introgression of mitochondrial DNA between these species was previously reported, which suggested they can hybridise.

A new species of (Perciformes: Cichlidae) from Lake Mweru in the Upper Congo River System.

Pseudocrenilabrus pyrrhocaudalis sp. nov. is described from Lake Mweru in the upper Congo River drainage, on the border of the Democratic Republic of Congo and Zambia.

Testing the potential of DNA barcoding in vertebrate radiations: the case of the littoral cichlids (Pisces, Perciformes, Cichlidae) from Lake Tanganyika.

We obtained 398 cytochrome c oxidase subunit I barcodes of 96 morphospecies of Lake Tanganyika (LT) cichlids from the littoral zone. The potential of DNA barcoding in these fishes was tested using both species identification and species delineation methods. The best match (BM) and best close match (BCM) methods were used to evaluate the overall identification success.

Hidden biodiversity in an ancient lake: phylogenetic congruence between Lake Tanganyika tropheine cichlids and their monogenean flatworm parasites.

The stunning diversity of cichlid fishes has greatly enhanced our understanding of speciation and radiation. Little is known about the evolution of cichlid parasites. Parasites are abundant components of biodiversity, whose diversity typically exceeds that of their hosts.

Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north-eastern part of the Congo basin.

This study evaluates the utility of DNA barcoding to traditional morphology-based species identifications for the fish fauna of the north-eastern Congo basin. We compared DNA sequences (COI) of 821 samples from 206 morphologically identified species. Best match, best close match and all species barcoding analyses resulted in a rather low identification success of 87.

Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes.

The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region.

Morphology, molecules, and monogenean parasites: an example of an integrative approach to cichlid biodiversity.

The unparalleled biodiversity of Lake Tanganyika (Africa) has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations.

Contrasting parasite communities among allopatric colour morphs of the Lake Tanganyika cichlid Tropheus.

Background: Adaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations.