Taxonomic diversity, distribution, and ecology of the freshwater fishes of the Zambezian Lowveld Ecoregion in southern Africa: A systematic review.

The Zambezian Lowveld Ecoregion (ZLE) is one of the 22 freshwater ecoregions covering southern Africa. This ecoregion covers ~520,418 km2 and extends from south of the Zambezi Delta in the north to the uMngeni River basin in the south. This study aimed to compile a comprehensive synthesis of the available information on the diversity and distribution of freshwater fishes in this ecoregion based on natural history collection holdings by reviewing the published scientific literature. In total, 105 native species belonging to 39 genera and 17 families were recorded from the ZLE. An important proportion, 20 (19%), of the species are considered to be narrow-range endemics. Nevertheless, the majority of them (81%) are considered to have broad geographic ranges, with some even extending into adjacent ecoregions. However, recent and ongoing studies indicate that the current taxonomy often underestimates the species diversity and therefore overestimates the distribution ranges of the latter group of freshwater fishes concerned. The present synthesis brings to the fore existing knowledge gaps in species diversity and distribution ranges of freshwater fishes of this ecoregion and highlights the need for the use of integrative approaches to address the prevailing taxonomic conflicts.

Description of a new endemic Enteromius (Teleostei: Cyprinidae) from the upper Malagarazi in Burundi: Lessons for a protected area under implementation.

Recent collecting efforts in the upper Malagarazi basin (2013-2022) allowed for an integrative study based on qualitative (colour), quantitative (meristic and metric), and barcoding gene [mtDNA, cytochrome c oxidase (COI)] data of specimens similar to Enteromius sp. 'ascutelatus', being a previously identified, potentially, new species. Based on these data, the present study confirms its identification as a new species for science, which is here formally described as Enteromius nzigidaherai sp. nov. This new species belongs to the group of Enteromius species for which the last unbranched ray of the dorsal fin is flexible and devoid of serrations along its posterior edge. This species has a horizontal series of black spots at the midlateral level of the sides. Three congeneric species, known from the Congo basin sensu lato, with two of them also found in the upper Malagarazi basin, are most similar to it. However, E. nzigidaherai sp. nov. is distinguished from the two sympatric upper Malagarazi species, that is, E. quadrilineatus and E. lineomaculatus, at least by two meristics and two morphometrics. It is also distinguished from E. urostigma, known from the upper Congo basin, by two meristics and one, apparently related, morphometric. In addition, a barcoding (mtDNA, COI) study revealed that the specimens of E. nzigidaherai sp. nov. form a well-supported, separate lineage, with a K2P genetic distance of more than 10% with specimens identified as E. quadrilineatus and E. lineomaculatus, both originating from the upper Malagarazi basin and for which tissue samples were available. Finally, the new species was found to be endemic to the upper reaches of two left bank affluents of the upper Malagarazi basin: the Muyovozi and the Kinwa. However, both affluents are threatened by human activities, which seem to have resulted in its local disappearance as recent intensive collecting efforts in the latter affluent have remained unsuccessful. The species should thus be considered Critically Endangered (CR) according to IUCN criteria B1ab(ii,iv)c(i,iii). Therefore, it is hoped that the present description draws renewed attention to the importance of aquatic protection in the region by highlighting the need for the effective establishment of the Malagarazi Nature Reserve and concern for its optimal delimitation to efficiently protect the entire ichthyofauna of the upper Malagarazi, without excluding the fish species confined to its affluent rivers.

Hidden species diversity in the Enteromius Cope, 1867 (Teleostei: Cyprinidae) from the Aruwimi basin (Middle Congo) in the Okapi Wildlife Reserve (Democratic Republic of the Congo).

Two new African minnow species, Enteromius cerinus sp. nov. and Enteromius ruforum sp. nov., are described for science from the Angadiko River, a left-bank sub-affluent of first order of the Nepoko River, draining the north-eastern part of the Okapi Wildlife Reserve (OWR). Both new species belong to the group of Enteromius for which the last unbranched dorsal-fin ray is flexible and underrated. Within this morphological group, both are most similar to Enteromius kamolondoensis, especially in life colour pattern characteristics. However, Enteromius cerinus sp. nov. differs from E. kamolondoensis by its low number of circumpeduncular scales, 10-11 (vs. 12), low maximum body depth, 22.8%-25.7% standard length (Ls) (vs. 26.1%-30.0%), and long anterior and posterior barbel lengths, 32.6%-35.3% head length (LH) (vs. 23.6%-27.2%) and 41.6%-43.9% LH (vs. 30.3%-34.9%), respectively. Further, E. ruforum sp. nov. is also easily distinguished from E. kamolondoensis by its high maximum body depth, 30.6%-33.3% Ls (vs. 26.1%-30.0%), and small, isometric, eye diameter, 26.2%-28.0% LH (vs. 29.1%-31.9%). A barcoding study (mtDNA, cytochrome oxidase subunit I [COI]) revealed that specimens of both new species form lineages well differentiated from those of other available species. As such, (i) E. cerinus sp. nov. diverges from E. kamolondoensis by a K2P genetic distance (GD) of 10.3% and (ii) E. ruforum sp. nov. by a K2P GD of 11.2%. To the present day, the fish fauna of the left-bank sub-affluents of the Nepoko River, in general, remains poorly known or undocumented. Unfortunately, at the same time, multiple anthropogenic impacts are affecting this fauna, such as (i) the destruction of habitats along the river banks for agriculture and fishing and (ii) the use of illegal fishing practices, such as fishing with plant-based ichthyotoxins during ecopage, which is combined with dam building. As a result of the demographic growth, this ecopage results in overfishing and thus is threatening both new species in particular, but all other co-occurring fish species as well. Both new species, E. cerinus sp. nov. and E. ruforum sp. nov., should thus be considered Vulnerable (VU) according to IUCN criterion D2. It is therefore hoped that their discovery highlights the urgent need for a better protection and further in situ exploration of the reserve's freshwater (fish) biodiversity, in general, and that of those small sub-affluents, in particular.

On the occurrence and distribution of Synodontis nigrita and Synodontis violaceus (Siluriformes: Mochokidae) in the Nilo-Sudan, and Upper and Lower Guinea ichthyofaunal provinces.

Examination of the holotype of Synodontis nigrita, the type specimens of both its (potential) junior synonyms, Synodontis fascipinna and Synodontis ornatus, and an additional 306 specimens, previously identified as S. nigrita, confirmed that the interorbital width is the most important diagnostic character to distinguish S. nigrita from its Nilo-Sudanic (N-S), and Upper and Lower Guinea ichthyofaunal province congeners. Results revealed that this species has a typical N-S distribution. In addition, the occurrence of Synodontis violaceus in the Cross River is not corroborated. Therefore, it should be considered a typical West African species.

A new species of Parauchenoglanis (Auchenoglanididae: Siluriformes) from the Upper Lualaba River (Upper Congo), with further evidence of hidden species diversity within the genus.

Parauchenoglanis zebratus sp. nov. is a new species endemic to the Upper Lualaba in the Upper Congo Basin. It is distinguished from all its congeners known from the Congo Basin and adjacent basins by the presence of (1) distinctive dark-brown or black vertical bars on the lateral side of the body, at least for specimens about ≥120 mm LS , (2) a broad and triangular humeral process embedded under the skin and (3) a well-serrated pectoral-fin spine. Genetic analysis based on mtDNA COI sequences confirmed the genetic distinctiveness (2.8%-13.6% K2P genetic divergence) of P. zebratus sp. nov. from congeners within the Congo and adjacent river basins. The study also revealed additional undocumented diversity within P. ngamensis, P. pantherinus, P. punctatus and P. balayi, indicating the need for further in-depth alpha-taxonomic attention to provide more accurate species delimitations for this genus. The discovery of yet another new species endemic to the Upper Lualaba, and this well outside the currently established protected areas, highlights the critical need for further assessments to accurately document the species diversity to guide freshwater conservation prioritisation and biodiversity management in this region.

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. chochamandai. This new species, though highly similar to N. luapulae, can readily be distinguished from it by its lower number of lateral line scales, 41-46 (vs. 49-55), its pectoral fin reaching the pelvic-fin insertion (vs. not reaching the pelvic-fin insertion) and its pelvic fin reaching the base of the anal fin (vs. not reaching the base of the anal fin). Specimens of N. chochamandai display thickened pads on the first three pelvic-fin rays that exhibit intraspecific variation in development, which appears to be related to the flow-strength of the river in which these Nannocharax specimens occur. Nannocharax luapulae is redescribed and an updated identification key to the Nannocharax species of the Congo basin sensu lato is provided as well. Some fish conservation issues related to N. luapulae and N. chochamandai are also highlighted.

A new Parakneria Poll 1965 (Gonorhynchiformes: Kneriidae), 'Mikinkidi' from the Upper Lufira Basin (Upper Congo: DRC): Evidence from a morphologic and DNA barcoding integrative approach.

A new species, Parakneria alytogrammus, is described from the main stream of the Upper Lufira River. This species is easily distinguished from its congeners from the Congo Basin by its unique colouration, consisting of a low number of transversal bands on each of the caudal-fin lobes, 2 (vs. 3-5) and the presence of an uninterrupted lateral mid-longitudinal black band in fresh and preserved specimens (vs. absent). In addition, the new species differs from its Upper Lualaba congeners by the narrow width of its pectoral-fin base, 4.8-5.6% LS [vs. wider, 8.2-10.1% for P. lufirae, 8.6% LS for P. damasi (holotype), and 7.6-7.9% LS for P. thysi]. Finally, it differs from the only species currently known from the Luapula-Mweru system, P. malaissei, by having a short post-dorsal distance, 36.4-36.6% LS (vs. longer, 38.6-41.1% LS ) and a short post-pelvic distance of 40.0-40.6% LS (vs. longer, 41.4-44.1% LS ). Mitochondrial DNA-haplotypes of P. alytogrammus sp. nov. form a clade, which is sister to the P. thysi clade, and from which it diverges by a genetic (Kimura 2-parameter and uncorrected p) distance of 0.7% in the COI-barcoding locus. The Upper Lufira, one of the sub-basins of the Upper Congo Basin, remains poorly explored relative to its fish fauna. In contrast, the region is well explored with regard to its mineral wealth. Unfortunately, mining exploitation is carried out in the region without proper concern for the environment. Thus, the discovery of this new species for science calls for increased protection and aquatic biodiversity exploration in this mining region.

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. 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.

New phylogenetic insights into the African catfish families Mochokidae and Austroglanididae.

Several hundred catfish species (order: Siluriformes) belonging to 11 families inhabit Africa, of which at least six families are endemic to the continent. Although four of those families are well-known to belong to the 'Big-Africa clade', no previous study has addressed the phylogenetic placement of the endemic African catfish family Austroglanididae in a comprehensive framework with molecular data. Furthermore, interrelationships within the 'Big-Africa clade', including the most diverse family Mochokidae, remain unclear. This study was therefore designed to help reconstruct inter- and intrarelationships of all currently valid mochokid genera, to infer their position within the 'Big Africa clade' and to establish a first molecular phylogenetic hypothesis of the relationships of the enigmatic Austroglanididae within the Siluriformes. We assembled a comprehensive mitogenomic dataset comprising all protein coding genes and representing almost all recognized catfish families (N = 33 of 39) with carefully selected species (N = 239). We recovered the monophyly of the previously identified multifamily clades 'Big Asia' and 'Big Africa' and determined Austroglanididae to be closely related to Pangasiidae, Ictaluroidea and Ariidae. Mochokidae was recovered as the sister group to a clade encompassing Auchenoglanididae, Claroteidae, Malapteruridae and the African Schilbeidae, albeit with low statistical support. The two mochokid subfamilies Mochokinae and Chiloglanidinae as well as the chiloglanid tribe Atopochilini were recovered as reciprocally monophyletic. The genus Acanthocleithron forms the sister group of all remaining Mochokinae, although with low support. The genus Atopodontus is the sister group of all remaining Atopochilini. In contrast to morphological reconstructions, the monophyly of the genus Chiloglanis was strongly supported in our analysis, with Chiloglanis macropterus nested within a Chiloglanis sublineage encompassing only other taxa from the Congo drainage. This is an important result because the phylogenetic relationships of C. macropterus have been controversial in the past, and because we and other researchers assumed that this species would be resolved as sister to most or all other members of Chiloglanis. The apparent paraphyly of Synodontis with respect to Microsynodontis provided an additional surprise, with Synodontis punu turning out to be the sister group of the latter genus.

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., 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.

Description of two new miniature species of Hylopanchax Poll & Lambert, 1965 (Cyprinodontiformes: Procatopodidae), from northeastern Gabon, with an updated diagnosis of the genus based on morphology, colouration and osteology.

Two new species of the lampeye genus Hylopanchax are described from the Ivindo River basin in the Ogowe River drainage. Hylopanchax multisquamatus, new species, and Hylopanchax thysi, new species, differ from congeners by the presence of a hyaline urogenital male papilla with small black spots and a dark-brown reticulate pattern on the flanks of both males and females in preserved specimens. Hylopanchax multisquamatus is distinguished from congeners by the number of scales on the mid-longitudinal series (27-30 vs. 19-26, respectively) and by the relative anterior/posterior flank scale depth ratio (140%-150% vs. 170%-220%). Hylopanchax thysi is distinguished from all other congeners, except Hylopanchax paucisquamatus, by the presence of vertebrae (30 vs. 31-33) and is further distinguished from H. multisquamatus by the presence of a deeper caudal peduncle and much larger anterior flank scales. It is distinguished from H. paucisquamatus by the presence of a hyaline urogenital male papilla with small black spots and a dark-brown reticulate pattern on the flanks of both males and females in preserved specimens. Osteological data of Hylopanchax are presented for the first time, and an updated diagnosis based on external morphology, colouration pattern and osteology is provided. An osteological comparison with closely related species belonging to the genera Procatopus, Hypsopanchax and "Hypsopanchax" is presented. (a) A truncate and slightly downward-directed anterior process of the angulo-articular and (b) a guitar-shaped lachrymal with both its anterior and posterior margins sharply curved are here considered as diagnostic features of Hylopanchax.

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. 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.

Enteromius thespesios (Teleostei: Cyprinidae): a new minnow species with a remarkable sexual dimorphism from the south-eastern part of the Upper Congo River.

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.

Hidden species diversity in Marcusenius moorii (Teleostei: Mormyridae) from the Congo Basin.

New collections from the Yangambi Biosphere Reserve (YBR) and Okapi Wildlife Reserve (OWR) revealed the presence of two groups of specimens similar to, but different from Marcusenius moorii. To study both these groups, an integrated morphological and genetic (mtDNA, cytb) approach was used. This study revealed that one of the two groups is conspecific with Marcusenius lambouri, a junior synonym of M. moorii, which is herein revalidated, with M. moorii longulus as its junior synonym. Marcusenius lambouri differs from M. moorii by a higher number of lateral line scales (44-46 vs. 40-43), a shorter pectoral-fin length (14.6-19.9 vs. 20.3-25.2% standard length; LS ) and a more elongated body due to a usually shallower middle body depth (19.8-26.5 vs. 26.3-35.9% LS ). The other group revealed to be a new species for science, Marcusenius verheyenorum, which can be distinguished from its congeners with eight circumpeduncular scales by the following unique combination of characters: a rounded head with a terminal mouth; a short and deep caudal peduncle (middle caudal-peduncle depth, 44.9-54.6% caudal-peduncle length; LCP ), a deep body (middle body depth, 27.7-34.2% LS ), 38-43 scales on the lateral line, 40-41 vertebrae, 20-21 dorsal-fin rays and 26 anal-fin rays. Some specimens previously attributed to M. moorii were examined and reassigned to M. lambouri or M. verheyenorum. As a result, M. moorii and M. lambouri occur in sympatry in the middle Congo Basin, with the distribution area of M. moorii still further extending into the lower Congo Basin. Instead, the distribution of M. verheyenorum is limited to some right bank tributaries of the upstream part of the middle Congo Basin. Two museum records from the Lilanda River (YBR), collected in the 1950s and previously identified as M. moorii, were re-identified as belonging to the new species, M. verheyenorum. However, the species now seems locally extinct in that region, which reflects the significant anthropogenic effects even within this reserve.

Description of a new small-sized Synodontis species (Siluriformes: Mochokidae) that is important for local subsistence fisheries in the middle Lufira (upper Congo River, DR Congo).

Synodontis denticulatus sp. nov. is an endemic from the middle Lufira Basin and its associated tributaries and lakes. The species shows close morphological resemblance to Synodontis greshoffi and Synodontis unicolor, which are widespread Congo Basin and Bangweulu-Mweru endemic species, respectively. However, it differs from both S. greshoffi and S. unicolor by its non-villous skin (v. villous skin), strong and numerous serrations on the posterior margin of the dorsal spine (v. weak and fewer serrations), weak and few serrations on the posterior margin of the pectoral spine (v. strong and numerous serrations), relatively short maxillary barbels (v. long) and its small maximum standard length (89.1 mm LS v. 148.0 and 190.7 mm LS respectively). A DNA barcoding study (coI, mtDNA) revealed that S. denticulatus forms a distinct genetic clade with a genetic distance of 2.18% with S. greshoffi and 0.84% with S. unicolor. Synodontis denticulatus is caught regularly and abundantly as a by-catch in the gillnet fisheries in the middle Lufira lakes. Owing to its small overall size and large bony head, the species has usually no real commercial value but is an important food fish for the fishermen's families.

The Cyphomyrus Myers 1960 (Osteoglossiformes: Mormyridae) of the Lufira basin (Upper Lualaba: DR Congo): A generic reassignment and the description of a new species.

Within a comparative morphological framework, Hippopotamyrus aelsbroecki, only known from the holotype originating from Lubumbashi, most probably the Lubumbashi River, a left bank subaffluent of the Luapula River, is reallocated to the genus Cyphomyrus. This transfer is motivated by the fact that H. aelsbroecki possesses a rounded or vaulted predorsal profile, an insertion of the dorsal fin far anterior to the level of the insertion of the anal fin, and a compact, laterally compressed and deep body. In addition, a new species of Cyphomyrus is described from the Lufira basin, Cyphomyrus lufirae. Cyphomyrus lufirae was collected in large parts of the Middle Lufira, upstream of the Kyubo Falls and just downstream of these falls in the lower Lufira and its nearby left bank affluent, the Luvilombo River. The new species is distinguished from all its congeners, that is, firstly, from C. aelsbroecki, C. cubangoensis and C. discorhynchus, by a low number of dorsal fin rays, 27-32 (vs. higher, 36 (37), 34 (33-41) an 38 (38-40), respectively) and, secondly, from C. aelsbroecki, C. cubangoensis, and C. discorhynchus by a large prepelvic distance, 41.0-43.8% LS (vs. shorter, 39.7%, 38.9-39.1% and 37.0-41.0% LS , respectively). The description of yet another new species for the Upemba National Park and the Kundelungu National Park further highlights their importance for fish protection and conservation in the area. Hence, there is an urgent need for the full integration of fish into the management plans of these parks.

Integrative taxonomy reveals hidden diversity in the southern African darters genus Nannocharax Günther 1867 (Characiformes: Distichodontidae).

The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species. All methods delimited two species groups, and these are supported based on colouration patterning and morphology; the Nannocharax multifasciatus and the Nannocharax macropterus species groups and the delimited OTUs were assigned to each. Two putative new species were identified, Nannocharax cf. lineostriatus "Okavango" from the Okavango River in Angola and N. cf. lineostriatus "Kwanza" from the Kwanza River system in Angola. The distribution of Nannocharax dageti was confirmed for the Upper Zambezi and extended to the Okavango system, and an identification key for the southern Africa Nannocharax species is provided.

Description of Notoglanidium pembetadi new species (Siluriformes: Claroteidae) from the Kouilou-Niari River, Republic of the Congo.

A new claroteid catfish, Notoglanidium peinbetadi, is described from the Kouilou-Niari River basin (Republic of the Congo). This species can be distinguished from all other currently known Notoglanidium species as well as from the very similar Anaspidoglanis boutchangai, to which two specimens have erroneously been attributed in the past, by the following combination of characters: II, 10-13 dorsal-fin rays; long dorsal-fin base (21.1-24.4% SL); short predorsal distance (30.1-33.5% SL); and short prepelvic distance (40.1-45.4% SL).

Revision of Notoglanidium and related genera (Siluriformes: Claroteidae) based on morphology and osteology.

Apart from the well-demarcated genera Auchenoglanis and Parauchenoglanis, Auchenoglanidinae, one of the two sub-families of the African catfish family Claroteidae, suffers from poor resolution at the generic level. For the remaining genera, Notoglanidium, Liauchenoglanis, Platyglanis and Anaspidoglanis, generic discriminations are rudimentary. In addition, several included species are poorly defined and barely represented in scientific collections. Until now, no study has included morphological data for all currently known species, and for many species osteological data were non-existent. Molecular data for most species are lacking as well. Here, a comprehensive account of the morphology and osteology is given of all species included in these four genera. Using computed tomography (CT scanning) as well as clearing and staining, osteological characters were combined with biometric, meristic and other morphological data to revise the status of these genera and included species. Morphological and osteological data, submitted to a phylogenetic analysis, agree with metric and meristic data that all Liauchenoglanis, Platyglanis and Anaspidoglanis cannot be discerned from Notoglanidium; their genus and type species descriptions fail to be distinguished from Notoglanidium. Here their synonymy is proposed, resulting in a single valid genus, including nine species of which the validity is confirmed. A key to the genus and included species, as well as a diagnosis and description for each of them, are provided.

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. Monogeneans were isolated from the gills and stomach, mounted on glass slides with either Hoyer's medium or ammonium picrate-glycerin for 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 13 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 identified. A species richness (S) of 10 for O. mweruensis, S = 6 for C. rendalli and S = 2 for S. macrocephalus was recorded. Five parasite species were reported to be common amongst O. mweruensis and C. rendalli. According to cichlid species, the most prevalent parasite species was C. halli (prevalence [P] = 80.9%) on O. mweruensis, C. dossoui (P = 92.9%) on C. rendalli and C. karibae and C. zambezensis (both P = 9.1%) on S. macrocephalus. The parasite species with the highest mean intensity (MI) were G. nyanzae (MI = 8.7) on O. mweruensis, C. papernastrema (MI = 17.1) on C. rendalli and C. karibae (MI = 15) on S. macrocephalus. The findings indicate 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 all of them as they are recorded for the first time in the Lufira River Basin. CONCLUSIONS: This study highlighted the richness of monogenean communities in the Upper Lufira River Basin and is a starting point for future helminthological studies, such as on the use of fish parasites as indicators of anthropogenic impacts.