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The East African Great Lakes are inhabited by impressive radiations of cichlids that display a large variation in morphology, diet, colour pattern, and behaviour and have adapted to a large array of niches. Whilst most of these cichlids are bottom dwellers, a number of species have adapted to a pelagic environment and inhabit open waters. From the Lake Edward system, one pelagic species had been previously described, the zooplanktivorous Haplochromis pappenheimi. Our sampling revealed the Lake Edward system to be inhabited by two more pelagic species that were unknown to science and are formally described here, the zooplanktivorous Haplochromis pelagicus sp. nov. and the insectivorous H. aureus sp. nov. All three species seem mostly restricted to deepwater regions where the depth exceeds six metres in Lake Edward, except for H. pelagicus sp. nov., which also occurs in shallower regions of Lakes Edward and George and of the Kazinga Channel. Sexual dimorphism, mainly in head shape, was discovered in H. pappenheimi and H. pelagicus sp. nov. These differences suggest that females of these species have larger buccal cavities than males, which is most likely linked to female mouth brooding behaviour. This research was conducted within the framework of the BELSPO (Belgian Science Policy Ofce) funded BRAIN projects HIPE (Human impacts on ecosystem health and resources of Lake Edward) and KEAFish (The biodiversity, biogeography and evolutionary history of the northern basins of the Great African Lakes: the enigmatic fsh faunas of Lakes Kivu, Edward and Albert revisited) and an FWO (Research Foundation Flanders) funded PhD fellowship to NV (11E0520N). MM beneftted from a FishBase and Fish taxonomy training (2016) through the framework agreement of the RMCA with the Directorate-General for Development Cooperation and Humanitarian Aid. The feldwork by NV, MVS, and ED was supported by the FWO and feldwork by MVS by the King Leopold III Fund for Nature Exploration and Conservation. We thank L. Wasswa (Ugandan Fisheries Department) and M. Bifamengo (NaFIRRI, Uganda) for their help in collecting specimens, and W. Okello (NaFIRRI, Uganda) for valuable logistic support. We are grateful to M. Parrent (RMCA), O. Pauwels (IRSNB), J. Maclaine (NHMUK), and E. Aßel (ZMB) for curatorial services, E. Aßel for the provided photograph and X-ray image of the lectotype of H. pappenheimi, and support from the SYNTHESYS+ Project, http://www.synthesys.info/, which is fnanced by European Community Research Infrastructure Action under the H2020 Integrating Activities Programme, Project number 823827.

Oreochromis is the most important tropical freshwater fish genus for aquaculture purposes, with various introduction and translocation events having played an integral part of its management. Some Oreochromis species such as the Nile tilapia, O. niloticus, are thought to be superior for aquacultural purposes when compared to other species. Hence, understanding the admixed nature of the species within a native system is of key importance for the development of future broodstock. Using a combination of mitochondrial (COI) and nuclear (microsatellites) DNA, we tested for the presence of O. niloticus and O. leucostictus hybrids within the Lake Edward-George system. The present study revealed that, despite their natural overlapping ranges, hybridization between O. niloticus and O. leucostictus appears to be rare within the Lake Edward-George system, suggesting that the native populations of these two species may serve as suitable broodstock to develop future aquaculture strains. Moreover, our study provides the first COI sequences for O. leucostictus from its native range and adds to the growing database of O. niloticus sequences.

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., a fleshy appendage on the chin, and one usually with a poorly developed one) and 26 environmental variables was investigated in four affluents of the Luhoho River in the Albertine Highlands of the Upper Congo basin. A combination of univariate and multivariate analyses suggested that differences exist in habitat composition at localities where different Labeobarbus species were reported, and within different mouth phenotypes. The association of L. longidorsalis with the presence of cobbles and pebbles and of L. brauni with the presence of boulders suggests that the occurrence of chiselmouths phenotype is associated with stony habitats, whereas phenotypes with a mental lobe, i.e., Labeobarbus longifilis and L. paucisquamatus, mostly occupy habitats without stones. Differences in the distribution between these two species appear to be linked to physico-chemical parameters such as electrical conductivity and water temperature rather than substrate type. The findings of this study are relevant for developing guidelines that aim effective local preservation and conservation of these Labeobarbus species.

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. Here, we study the genetic consequences of these introductions by genotyping 213 Nile tilapia from native and introduced regions, focusing on the Congo Basin. Additionally, 48 specimens from 16 other tilapia species were included to test for hybridization. Using RAD sequencing (27,611 single nucleotide polymorphisms), we discovered genetic admixture with other tilapia species in several morphologically identified Nile tilapia from the Congo Basin, reflecting their ability to interbreed and the potential threat they pose to the genetic integrity of native tilapias. Nile tilapia populations from the Upper Congo and those from the Middle-Lower Congo are strongly differentiated. The former show genetic similarity to Nile tilapia from the White Nile, while specimens from the Benue Basin and Lake Kariba are similar to Nile tilapia from the Middle-Lower Congo, suggesting independent introductions using different sources. We conclude that the presence of Nile tilapia in the Congo Basin results from independent introductions, reflecting the dynamic aquaculture history, and that their introduction probably leads to genetic interactions with native tilapias, which could lower their fitness. We therefore urge avoiding further introductions of Nile tilapia in non-native regions and to use native tilapias in future aquaculture efforts.

Thickened lips have evolved several times within the cichlid flocks of the East African Great Lakes. This distinct and easily recognisable phenotype is a model trait to study convergent evolution. Lake Edward (Eastern Africa) contains a unique cichlid assemblage, which has remained largely understudied. Hitherto, only one cichlid species with lobed lips, Haplochromis labiatus, was known from this lake. This species has a blunt snout and rounded and mostly retrognathous jaws. However, we found specimens with lobed lips, but with acute snouts and slender and mostly prognathous jaws. These belong to a species, hitherto unknown to science: H. lobatus sp. nov. Both species occur sympatrically. We evaluated the morphological diversity within these species by investigating a total of 112 specimens using traditional and geometric morphometric approaches. Both species are formally (re)described and show a relatively large variation in their trophic morphologies, which complicates identification. Both have a small gape, stout outer teeth that strongly decrease in size laterad, and a lower jaw set anteriorly with procumbently-implanted outer teeth. Haplochromis labiatus differs from H. lobatus sp. nov. by a straight to convex vs. straight to concave head, a slightly shorter and broader lower jaw (27.7–34.3 vs. 31.2–40.7% HL; 71.4–92.4 vs. 48.5–70.5% LJL), and lobed lips that are thickened uniformly over their whole lengths vs. medially enlarged. Gut content observations revealed that both species have an insectivorous diet. While both exploit similar food sources, their morphological differences presumably prevent them from entering into direct ecological competition. ispartof: Journal Of Great Lakes Research vol:46 issue:5 pages:1079-1089 status: published

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. Phylogenetic analyses including 28 complete mitogenomes from representatives of the subfamily Smiliogastrinae (Cyprinidae), showed that Caecobarbus was nested within a clade including representatives of the genus Enteromius. The data presented in this study provide information on the molecular identification and classification of this threatened species. The results further suggest the need for a taxonomic revision of the genus Enteromius.

This study highlights the value of museum collections in invasion biology. It focuses on introduced tilapias, Oreochromis niloticus and Coptodon rendalli in the Congo Basin and their monogenean (Platyhelminthes) gill parasite fauna. O. niloticus was introduced throughout the Congo Basin while C. rendalli was introduced into the Lower Congo, but is native to the Middle and Upper Congo. In order to study the impact of these stocking events on the native parasite community we investigate the co-introduction and host switching of their parasites. Post-introduction material is compared with pre-introduction samples from museum collections of 5 native tilapias in the Congo Basin. Nine of the known parasites of O. niloticus were co-introduced, while one, Cichlidogyrus rognoni, is missing and possibly not established. In contrast, no parasite species were found co-introduced with C. rendalli into the Lower Congo. The parasite fauna of Tilapia sparrmanii shared no species with O. niloticus. Oreochromis mweruensis shared five species with O. niloticus, but these were also found on the pre-introduction samples, and are considered native to both hosts. We report three putative host switches: Cichlidogyrus sclerosus and Cichlidogyrus tilapiae to Coptodon tholloni in the Lower Congo Basin and Gyrodactylus nyanzae to C. rendalli in the Upper Congo. ispartof: Biological Invasions vol:22 issue:9 pages:2825-2844 status: published

The present study reports on length‐weight relationships (LWRs) for 37 of the most abundant fish species in the Lefini River basin, one of the largest right bank tributaries of the Congo River in the Republic of the Congo. The study area comprised 12 stations along 103 km of the river. Each station was sampled during March 2007 to August 2008 following standardized methods utilizing five monofilament gill nets of 10, 12, 15, 20 and 30 mm mesh size. Sample size, lengths, weights, LWRs, 95% confidence intervals of a and b, coefficient of correlation r² and growth type are provided for each species. Values of allometric coefficient b of the LWRs (W = aSLᵇ) ranged from 2.556 for Synodontis nigriventris to 3.363 for Brycinus poptae. These results represent the first study of length‐weight relationships for fish species in a large affluent of the Congo basin as a whole.

ispartof: HYDROBIOLOGIA vol:849 issue:8 pages:1743-1762 status: published

Cichlid radiations often harbour closely related species with overlapping niches and distribution ranges. Such species sometimes hybridise in nature, which raises the question how they can coexist. This also holds for the Tanganyika mouthbrooders Ophthalmotilapia ventralis and O. nasuta. Earlier studies found indications of asymmetrical hybridisation with females of O. ventralis accepting males of O. nasuta, but not the other way around. We hypothesised that this was due to differences in the capacity for species recognition. Given the higher propensity of O. ventralis females towards hybridisation, we expect a reduced ability for species recognition in O. ventralis females, compared to O. nasuta females. We staged two experiments, one focusing on 22 female O. nasuta and one on 21 female O. ventralis. These fish were placed in one half of a tank and briefly exposed to a conspecific or a heterospecific male, a conspecific female, or nothing (control). Female response was evaluated by scoring six tracking parameters and by noting the occurrence of ten discrete behaviours before and during the encounter. Females always responded to the presence of another fish by approaching it. Remarkably, for both O. nasuta and O. ventralis, we did not find a different response between encounters with conspecific males and females. However, in agreement with our hypothesis, females of O. nasuta behaved differently towards conspecific or heterospecific males, whereas females of O. ventralis did not. When presented with a heterospecific male, females of O. nasuta performed a lower number of ‘ram’ behaviours. Additionally, they never displayed the ‘flee’ behaviour, a component of the species’ mating repertoire that was seen in all but one of the presentations with a conspecific male. Our findings show that differences in species recognition at first encounter predict to a large degree the outcome of the mating process, even in the absence of mating behaviour.

BackgroundMonogenean 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).MethodsOreochromis 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.ResultsA 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).ConclusionsThis 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.

International audience; The group of large five-spotted Hemichromis species from West Africa and Lower Guinea was revised using an integrative approach combining morphometry (measurements, meristics and colour patterns) and genetics (cytochrome b gene). Specimens from 100 populations were sorted into three main groups on the basis of morphological criteria. Samples from Lake Bosumtwi clustered together with others from West Africa in a large well-supported clade (bootstrap values and posterior probabilities: 98/96/100), both in morphometric and genetic analyses, raising again the hypothesis of synonymy of H. frempongi with H. fasciatus. Samples from southern Lower Guinea, including the type locality (Gabon) of H. elongatus, constituted a second weakly resolved cluster (64/38/51), resulting from a potential admixture of populations of diverse origins which share common morphological traits. Populations from northern Lower Guinea (Atlantic coastal basins) and the upper Chad basin in Cameroon formed a third strongly supported clade (99/100/100), which corresponds to a new species, Hemichromis camerounensis sp. nov., herein described.

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. A morphometric study on 47 specimens from Lake Edward revealed the presence of three new species with an oral-shelling morphology: Haplochromis concilians sp. nov., H. erutus sp. nov. and H. planus sp. nov. All three species are formally described. Stomach-content observations confirmed an opportunistic oral-shelling ecology for H. concilians sp. nov. and H. erutus sp. nov. Within H. planus sp. nov., only large specimens displayed a specialised oral-shelling morphology, but their stomachs were nearly empty, while small specimens consumed mainly Ostracoda and Hydrachnidia. Remarkably, the three species differed considerably in morphology from each other, but they each resembled oral-sheller species from Lake Victoria.

The unknown status of inland fish stocks hinders their sustainable management. Therefore, increasing stock status information is important for sustainable inland fisheries. Fisheries reference points were estimated for five exploited fish species (11 stocks) in the Lake Edward system, East Africa, which is one of the most productive inland water systems. The aim was to ascertain the status of the fisheries and establish reference points for effective management. The reference points were based on four linked stock assessment approaches for data‐limited fisheries. Estimates showed poor stock status with the stocks defined as either collapsed, recruitment impaired or overfished. However, higher catches could be obtained under sustainable management. Estimates of maximum sustainable yield (MSY) and supporting biomass (Bmsy) are provided for 10 of the stocks as targets for rebuilding plans. The immediate target of management should be rebuilding biomass to Bmsy. Applicable measures include shifting length at first capture to the length that maximizes catch without endangering size structure and biomass, and livelihood diversification out of fisheries.

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.

A revision was done on the species of Enteromius Cope, 1867 (Cypriniformes: Cyprinidae) from the Lake Edward system with a smooth, flexible third unbranched dorsal fin ray without serrations. Specimens with these characteristics had previously been attributed to E. perince and E. stigmatopygus . A combination of a genetic (COI, mtDNA) and a morphometric approach was used. Based on the COI gene, we found two groups with a distance of 8.5%, though neither of the two corresponded to E. perince or E. stigmatopygus . One group revealed to be conspecific with E. alberti , previously a synonym of E. stigmatopygus , described from the Rutshuru River, May-Ya-Moto (DRC, Lake Edward system), and revalidated here. In addition, E. cercops , described from the Nzoia River (Kenya, Lake Victoria basin), is put in synonymy with E. alberti . The second group was most similar to E. mimus , but differed morphologically somewhat from the types of E. mimus . Therefore, specimens of this group were identified as E. cf. mimus . Morphologically, E. alberti can be separated from E. cf. mimus based on a higher number of lateral line scales and smaller values for interorbital width, pre-pelvic distance, body depth, maximum and minimum caudal peduncle depth, head width and head depth.

The Lake Edward system in Eastern Central Africa, including Lakes Edward and George and their associated rivers, is home to a species assemblage of endemic haplochromine cichlids. Currently, 36 of these species have been formally described, while it is estimated that the system may harbour a total of 60 species. Species flocks of haplochromine cichlids are morphologically and ecologically very diverse and have radiated into many specialised trophic niches. Paedophagy is the feeding on eggs and larvae. In Haplochromis, most paedophages steal fry and eggs from the buccal cavities of mouthbrooding female cichlids. Hitherto, one formally described species with this diet is known from the Lake Edward system: Haplochromis taurinus. We performed a morphometrical revision of all species of Haplochromis from this system with a morphology that suggests a paedophagous diet: long oral jaws set with small teeth. Sixty-eight specimens were studied by taking 28 measurements and 20 counts and by performing stomach content observations. We discovered that H. paradoxus also had a paedophagous diet. Our analyses further revealed the presence of three new species: H. gracilifur sp. nov., H. molossus sp. nov., and H. relictidens sp. nov. All five of these species were described or redescribed.

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. Our aim is to test the hypothesis that reproductive behaviour acts as a prezygotic barrier that prevents frequent hybridisation in sympatric Ophthalmotilapia species. We performed a quantitative analysis of twelve reproductions (four for O. ventralis, six for O. nasuta, one for O. boops, and one between a female O. ventralis and a male O. nasuta). Although similar ethograms were obtained for these reproductions, the O. ventralis and O. boops males displayed a behaviour that was never performed by O. nasuta males. This behaviour was displayed during courtship and we called it ‘invite’. In O. ventralis, we could show that it was associated with the emission of a single pulse sound. The comparison of O. nasuta and O. ventralis reproductive behaviours also revealed some quantitative differences: O. ventralis males showed the location of the bower more often to the female, whereas O. ventralis females followed the male more often. The similarity between the reproductive behaviours in O. ventralis and O. nasuta could explain the occurrence of the heterospecific spawning event recorded between an O. nasuta male and an O. ventralis female. Importantly, few eggs were laid and the maternal mouthbrooding that resulted from this heterospecific reproduction only lasted for two days, which suggested the abortion of egg development. Hence, in the absence of conspecifics, courtship and mating behaviours alone do not constitute perfect prezygotic barriers between these two species.

This study represents the first exploration of the parasite fauna of cichlid fishes in the Mweru-Luapula subregion (Central Africa). Twelve species of cichlids and 14 species of Monogenea from three genera (Cichlidogyrus, Gyrodactylus and Scutogyrus) were collected. We present a first record of the gill parasite fauna of eight host species, Oreochromis mweruensis, Orthochromis sp. ‘Mambilima’, Sargochromis mellandi, Serranochromis angusticeps, S. stappersii, S. thumbergi and Tylochromis mylodon. The host range of 10 parasite species was expanded. The study further includes the description of Cichlidogyrus consobrini sp.n. from S. mellandi and Orthochromis sp. ‘Mambilima’. A new morphotype of C. halli is characterized and three species, C. papernastrema, C. quaestio and C. zambezensis are redescribed. Furthermore, the biodiversity and host-specificity of these parasites are compared with cichlid parasites from Lake Kariba and Cameroon. Two species, including C. consobrini sp.n. and a new morphotype of C. halli, are putative endemics. Additionally, the parasite fauna is highly similar in species composition to Lake Kariba, but in Bangweulu-Mweru the same parasite species are more host-specific, probably because of hydrogeographical differences between the two regions. This research was supported by the Belgian Federal Science Policy Office (BRAIN-be Pioneer Project BR/132/PI/TILAPIA), the University Development Cooperation of the Flemish Interuniversity Council (VLIR-UOS, South Initiative Renforcement des capacites locales pour une meilleure evaluation biologique des impacts miniers au Katanga (RDC) sur les poissons et leurs milieux aquatiques, ZRDC2014MP084) and the Mbisa Congo project, a framework agreement project of the RMCA with the Belgian Development Cooperation. M.P.M.V. was supported by a travel grant from the Research Foundation - Flanders (FWO-Vlaanderen) and Czech Science Foundation project no. P505/12/G112 (ECIP). Moise Katumbi Chapwe is cordially thanked for his kind hospitality and support. Also E. Abwe, B. Katemo Manda and C. Mukwene Mulele are cordially thanked for their help with the fish sampling, and W. Fannes, M. Kasongo Ilunga Kayaba and C. Kalombo Kabalika for their effort in parasite preparation. M. Barson, T. Dube and the technical team at the University of Zimbabwe Lake Kariba Research Station are thanked for delivering fresh gills of S. macrocephalus from Lake Kariba, Zimbabwe; J.-L. Justine (MNHN) and A.J. Phillips (Smithsonian) for the loan of type material; I. Přikrylová for sharing her expertise on Gyrodactylus; M. Van Steenberge for his valuable input regarding this ecoregion and its ichthyofauna; A. Henrard for his help with stacking images; G. Cael for his help with constructing fig. 1; and two anonymous referees for their valuable comments.

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.

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. We conclude that all specimens belong to one valid species, H. pharyngalis, and consider H. petronius to be a synonym.

Conspicuous characters are often useful in species identification. Yet, identification and delineation are two different processes, and such characters do not necessarily provide the best basis on which species can be delineated. This is illustrated by the case of the Labeo with papillary lips from the Congo basin. Traditionally, species delineation in this group was based on a conspicuous trait: the shape of the dorsal fin, which shows a profound degree of differentiation. Morphometric analyses were performed on 185 specimens both with and without measurements taken on this fin. The groups obtained using these two approaches were compared with those obtained through DNA barcoding. For this, 24 sequences of the standard barcoding COI gene were obtained. Species delineations based on morphological and molecular results were in agreement when the shape of the dorsal fin was ignored. This suggested that of the five nominal species known from the Congo basin, L. altivelis, L. rosae, L. lineatus, L. weeksii and L. maleboensis, only the former three remain valid. Consequently, L. weeksii was synonymised with L. altivelis and L. maleboensis with L. lineatus. The sole Congo basin endemic is L. lineatus as L. altivelis and L. rosae also occur in more southern basins. The use of the shape of the dorsal fin in morphological studies has previously led to overestimates of species diversity in this group. This is due to the fact that L. altivelis shows a remarkable amount of geographical variation for this trait. The large amount of intra- and interspecific variation in this character was caused by differential allometric growth in different parts of the dorsal fin.

Recently, specimens belonging to the genus ‘Haplochromis’ have been found in the Ituri River (Congo basin). They clearly do not belong to any of the species known from the Congo basin, but strongly resemble ‘H’. aeneocolor from the Lake Edward/George system. We examined whether this population represents a new species or is conspecific with ‘H’. aeneocolor. A morphological comparative study was executed based on 11 counts and 23 measurements on 64 specimens. The results revealed the Ituri specimens to differ from the types of ‘H’. aeneocolor in snout length, premaxillary pedicel length and eye diameter. Since these few differences are correlated, and head morphology is known to be subject to adaptive responses in haplochromine cichlids, they were considered the result of morphological adaptation to a riverine habitat rather than an indication of heterospecificity. Probably, ‘H’. aeneocolor has accidentally been introduced into the Ituri region together with tilapias used in aquaculture, and has subsequently established a stable population in a riverine environment. As fish introductions can have a severe impact on aquatic ecosystems, improving our knowledge as well as a good management of aquacultural activities is essential.

A new minnow species, Enteromius thespesios, is described from the south-eastern part of the upper Congo River; that is, the Kalule Nord, the Luvilombo and the Chambeshi Rivers. Enteromius thespesios belongs to the group of the soft-rayed species of Enteromius from the Congo Basin; that is, those with a weakly ossified, flexible last unbranched dorsal-fin ray that lacks serrations along its posterior edge. Within this group, E. thespesios is most similar to E. humeralis, from which it is distinguished by a higher number of circumpeduncular scales and shorter anterior and posterior barbels. Enteromius thespesios is a rheophilic and territorial species. It exhibits a marked sexual dimorphism, with males having: a red band towards the distal edge of dorsal, caudal and, to a lesser degree, anal fin; nuptial tubercles; a longer snout; longer pectoral fins; a shorter anal fin. This study gives extensive consideration to sexual shape differences for a species of Enteromius and also briefly reviews the current knowledge of sexual dimorphism in the species of Enteromius from the Congo Basin. Some conservation issues related to the new species are also highlighted. ispartof: JOURNAL OF FISH BIOLOGY vol:96 issue:5 pages:1160-1175 ispartof: location:England status: published

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 (δ 13C, δ 15N) 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 (δ 2H) 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).Overall, our results show that we gained power to distinguish sources by using a multiple tracer approach and we were able to discriminate aquatic versus terrestrial sources (esp. including hydrogen isotopes). Fish δ 2H values were clearly correlated with their food preferences and revealed a high level of variation in the degree of allochthony in these tropical aquatic communities.At the community level, it is clear that terrestrial C3 plants are an important source fueling the Congo River food web. However, in order to better constrain source contribution in these complex environments will require more robust constraints on stable isotope values of algal and methane‐derived C sources., Our study points toward a general significance of terrestrial C3 plants (allochthonous sources) for the fish and invertebrate communities in Afrotropical systems such as the Congo River basin. However, results showed a high variability of allochthony within communities of this large tropical aquatic system.

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. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non-Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east-coast ichthyofaunal province.

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. Most morphospecies (92.8%) corresponded to distinct clusters of DNA barcodes. Of the four morphospecies present in both neighbouring ichthyological provinces, only one showed DNA barcode divergence

A review of the tumultuous history of the alpha- and genus-level taxonomy of the hexaploid African Torini, i.e. Labeobarbus s.l. (synonym: Varicorhinus), as well as of the closely related monospecific genera Acapoeta and Sanagia, is provided. The main purpose of the present paper is to provide a continental framework for multidisciplinary research on this megadiverse vertebrate group. Based on the inspection of almost all relevant type specimens, a complete and fully annotated checklist of all valid species and junior synonyms is provided for each of the four nominal genera. It comprises ∼275 nominal taxa, 125 of which are valid African Labeobarbus spp. and three of which are formally named hybrid phenotypes. Particular attention is drawn to the diversity and taxon-specific distribution of mouth phenotypes, which previously served as generic identification characters, i.e. ‘rubberlips’ with strongly developed, sometimes hypertrophied lips and a mental lobe, and ‘chiselmouths’ (former Varicorhinus spp.) with a cornified sharp cutting edge on their lower jaw. Interestingly, many species are polymorphic and include a large array of intermediate mouth phenotypes. The recurrent occurrence of similar mouth phenotype diversity within, but also far beyond, the borders of Labeobarbus s.l. is highlighted, raising numerous evolutionary questions. © 2016 The Linnean Society of London

Pellegrin rejected the validity of Monostichodus elongatus, described by Vaillant and type species of the genus Monostichodus, based on the lack of a proper species description, and redescribed Vaillant's specimens as Hemistichodus vaillanti. After review of the relevant articles in the International Code of Zoological Nomenclature, however, no arguments were found to consider M. elongatus as a nomen nudum. This implies that Hemistichodus should be considered as a junior synonym of the genus Monostichodus, which includes three valid species: M. elongatus (with Hemistichodus vaillanti as a junior synonym), M. mesmaekersi and M. lootensi.

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. Six of these are herein described: Cichlidogyrus bixlerzavalai n. sp. and Cichlidogyrus omari n. sp. from T. praecox, Cichlidogyrus calycinus n. sp. and Cichlidogyrus polyenso n. sp. from H. elongatus, Cichlidogyrus kmentovae n. sp. from H. stellifer and Onchobdella ximenae n. sp. from both species of Hemichromis. On Cichlidogyrus reversati a ridge on the accessory piece was discovered that connects to the basal bulb of the penis. We report a putative spillback effect of the native parasites Cichlidogyrus berradae, Cichlidogyrus cubitus and Cichlidogyrus flexicolpos from C. tholloni to the introduced C. rendalli. From our results, we note that the parasite fauna of Lower Congo has a higher affinity with the fauna of West African and nearby freshwater ecoregions than it has with fauna of other regions of the Congo Basin and Central Africa. Six espèces nouvelles de Dactylogyridae (Platyhelminthes, Monogenea) parasites des branchies de cichlidés (Teleostei, Cichliformes) du bassin du Bas Congo. Le cours du Bas Congo est caractérisé par un estuaire bordé de mangroves et, plus en amont, par de nombreuses barrières hydro-géographiques formées de rapides ou de gorges étroites. Nous avons échantillonné dans cinq localités au niveau des mangroves et dans quatre autres en amont sur la rive gauche du fleuve, dans des affluents ou des étangs. Nous avons trouvé, sur les branchies de Coptodon tholloni, Coptodon rendalli, Hemichromis elongatus, Hemichromis stellifer et Tylochromis praecox, 17 espèces de parasites (Dactylogyridae et Gyrodactylidae, Monogenea), dont huit sont nouvelles pour la science. Six d’entre elles sont décrites ici : Cichlidogyrus bixlerzavalai n. sp. et Cichlidogyrus omari n. sp. sur T. praecox, Cichlidogyrus calycinus n. sp. et Cichlidogyrus polyenso n. sp. sur H. elongatus, Cichlidogyrus kmentovae n. sp. sur H. stellifer et Onchobdella ximenae n. sp. sur les deux espèces d’Hemichromis. Nous décrivons, chez Cichlidogyrus reversati, une arête sur la pièce accessoire qui la connecte avec l’ampoule basale basal du pénis. Nous notons un probable transfert latéral des espèces autochtones Cichlidogyrus berradae, Cichlidogyrus cubitus et Cichlidogyrus flexicolpos de C. tholloni vers l’espèce introduite C. rendalli. Nos résultats montrent que la faune parasitaire du Bas Congo présente plus d’affinités avec les faunes d’Afrique de l’Ouest ou des écorégions d’eau douce voisines, qu’avec celles des autres parties du bassin du Congo ou de l’Afrique Centrale.

Keywords: Ethiopia; fish biomass; Microcystis; reservoir ecology; water clarity Summary 1.In semi-arid regions, the construction of small reservoirs is important in alleviating water shortage, although many have poor water quality with high turbidity and dense blooms of algae and cyanobacteria, and there are large differences in the ecology of such reservoirs. 2.We took advantage of two exceptionally dry years in northern Ethiopia to study the effect of a dry period and the associated fish kills on reservoir ecology and water quality. We studied 13 reservoirs, seven of which dried up in 2009. Four of the latter dried up again in 2010. We monitored the ecology of these reservoirs from 2009 to 2011, hypothesising that the pattern of reservoir drying would explain ecological differences among them. 3.Reservoirs that refilled after drying had a significantly lower fish biomass, lower biomass of phytoplankton (expressed as chlorophyll-a) and cyanobacteria (Microcystis), clearer water, greater macrophyte cover and lower nutrient concentrations than reservoirs that did not dry. Although the differences in water quality were most striking in the wet season after a drying event, there were persistent effects on reservoir ecology. The three categories of reservoirs we distinguished, based on their behaviour in 2009 and 2010, also showed differences in 2004, a year during which none of the reservoirs dried out. While drying evidently results in better water quality, we could not disentangle the effects of drying per se from that of reductions in fish biomass. The total combined effect was highly significant in all 3 years, whereas the separate effects of drying and loss of fish were only significant in 2004. 4.Our results suggest that differences in water quality and ecology among reservoirs depend on their propensity to dry out. Drying might be used as a restoration measure to reduce potentially harmful cyanobacterial blooms in reservoirs.

Intra-specific morphological variation in the cichlid Tropheus duboisi from 10 localities over its entire known distribution area along the central eastern and northern shore of Lake Tanganyika was investigated. This revealed significant differences between various populations that are geographically isolated. These morphological observations only partially correspond to the results of a haplotype network, based on mtDNA. In addition, a difference in the timing of the onset of the adult colour pattern was discovered for one isolated population. The occurrence of morphological intra-specific differentiation is discussed with respect to the basal position of T. duboisi within Tropheus as well as to the presumed morphological stasis of the genus.