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The fish biodiversity in the Congo River and its tributaries is extremely rich but the information on fish communities in the headwaters in terms of catch and biomass estimates is rare. Fishes in the running and stagnant waters in this region are of vital importance as a food resource for local residents. This study aimed to describe the fish community, catch, and biomass in the three headwater streams Bambou, Lebomo, and Bongo in the Lake Tumba Landscape (LTL) of the Democratic Republic of the Congo. Such information is of vital importance as a benchmark to understand the sustainability of the fish population for future generations of residents of the LTL. The field data were collected from 2007 through 2011, including dry and wet seasons. Here we present the results of this systematic, multi-annual study which was the first for fishes in streams of this region. In total, 50 species of 15 families were found in the nutrient-poor brown waters of these streams where high concentrations of humic acids cause a low pH. Among abundant species occurring in all three streams were the cyprinid Enteromius holotaenia (Boulenger, 1904), the mormyrid Marcusenius moorii (Günther, 1867), the alestids Clupeocharax schoutedeni Pellegrin, 1926 and Bryconaethiops boulengeri Pellegrin, 1900, and the clariid Clarias angolensis Steindachner, 1866. Bongo Stream was distinguished from the others by a rich abundance of Alestopetersius compressus (Poll et Gosse, 1963). The presence of several species at low pH (between 5.0 and 5.5) is new information that lowers the bottom of the pH interval for these species compared to earlier reports. The maximum total length (TL) of some other species was by 5-20 percentage points higher than those reported earlier. The median weight per unit effort (WPUE) in the streams varied between 30 and 115 g per hour during the dry seasons and between 18 and 86 g per hour during the wet seasons. The fish biomass in the streams varied between 0.05 and 0.7 g ⋅m-2 with a median 0.14 g ⋅ m-2. This relatively low value compared to other tropical headwaters may be a result of the low pH and dark color of these headwaters. The results of the study serve as a reference point to which future monitoring of fish fauna can be compared for sustainable management of the LTL. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Six populations of morphologically similar Enteromius specimens with a weakly thickened and serrated dorsal spine from the Lowa basin were investigated using an integrative approach including qualitative characters, multivariate morphometrics, and DNA analyses (mtCOI and ncMyh6). These populations are nested within the COI lineage of the E. miolepis species-complex, but differ from all known Enteromius species from the Congo basin, by their dorsal spine morphology, colour pattern, and scale pattern at the dorsal-fin base. In addition, they represent two distinct COI lineages (genetic distance: 5.6–6.1%), with four populations forming a single well-supported lineage described as a new species, Enteromius radari sp. nov. The two remaining populations are sister to the E. miolepis lineage from the Itimbiri. The incongruent position of these two populations in the COI tree may point to past introgressive hybridization events, incomplete lineage sorting, or recent speciation. Analysis of a ncDNA marker (Myh6) did not provide more information due to its slow mutation rate. These results are indicative for introgression or mtDNA capture and provide the first report for such an evolutionary event in Enteromius from the Congo basin. [ABSTRACT FROM AUTHOR]

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