Ichthyofauna of the Itimbiri, Aruwimi, and Lindi/Tshopo rivers (Congo basin): Diversity and distribution patterns

Abstract

Background. Although the Congo basin is the second largest river basin in the world and it has been considered a biodiversity hotspot for fish, still many parts of this basin remain poorly studied. In this study, we examined the poorly known ichthyofauna of three major north-eastern tributaries of the Congo basin (Itimbiri, Aruwimi and Lindi/Tshopo). A checklist of the ichthyofauna is provided and two synonymies are presented. As such, it contributes to unraveling the poorly known fish diversity in the whole Congo basin. An improved knowledge of the ichthyofauna is a sound baseline for further studies and conservation Material and methods. Fish specimens from five recent expeditions have been identified, and the older collection material from the study area, housed at the Royal Museum for Central Africa and other institutions has been checked and re-identified when necessary. Results. In total, 320 species were recorded, 232 of which from the Itimbiri, 246 from the Aruwimi, and 187 from the Lindi/Tshopo, with the Mormyridae being the most dominant family in all three basins. Micralestes sardina Poll, 1938 is relegated to synonymy with Micralestes humilis Boulenger, 1899, and Enteromius trinotatus (Fowler, 1936) is designated as a replacement name for Enteromius tetraspilus (Pfeffer, 1896). Within the Aruwimi, a clear difference in species richness and composition is apparent between the headwaters (Ituri/Epulu) and the lower reaches near the Congo main stream. The headwaters are characterised by low species richness, with the Cyprinidae being the most dominant family, while the lower reaches are more species rich, with mormyrid species being the most dominant. The presence of two waterfalls on the Ituri/Epulu has a noticeable impact on the fish distribution. Finally, the hypothesis that an ancient connection between the north-eastern part of the Congo basin and the region of the Albertine Rift is still reflected in their present ichthyofauna is not confirmed. Conclusions. This study provides a first checklist of the ichthyofauna in the north-eastern tributaries of the Congo basin, and illustrates the influence of physical barriers on fish diversity and distribution.

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

“…The population from the Congo Basin, however, might constitute a different species. In a comparison of the ichthyofauna of the north‐eastern tributaries of the Congo Basin and the Lake Edward system, no evidence was found of recent exchange of other fish taxa (Decru et al ., ). Most species of the Edward system that also occur in the River Nile are large species such as B. docmak , O. niloticus , C. gariepinus and M. kannume .…”

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

“…The Congo Basin is the second largest catchment area in the world after the Amazon Basin and is characterized as a hotspot of fish diversity (Snoeks, Harrison, & Stiassny, ), with about 1,000 described species from the region excluding lakes Kivu and Tanganyika and the Malagarazi system (Froese & Pauly, ). Despite more than a century of taxonomic efforts with numerous field expeditions, local inventories and new species descriptions (e.g., Boulenger, ; Decru et al, ; Roberts & Stewart, ; Shumway et al, ; Stiassny & Mamonekene, ; Van Steenberge, Vreven, & Snoeks, ; Wamuini, Vreven, Vandewalle, Mutambue, & Snoeks, ), its fauna remains poorly documented and large areas of the Congo Basin remain underexplored (Thieme et al, ). The Lower Guinean province has been more intensively studied in the last decades (e.g., Stiassny, Teugels, & Hopkins, ; Walsh & Mamonekene, ).…”

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

“…Finally, these specimens also differ from L. macroceps (Fowler, ), an endemic species of the Epulu River, a right bank affluent of the Ituri/Aruwimi (Middle Congo basin), in the number of lateral line scales (35–36 vs . 32–33) (Decru, ; Fowler, ) and based on the mtDNA COI and Cytb results (Kisekelwa, ). Thus, the Lowa specimens probably belong to a new species for science, hereafter named Labeobarbus sp.…”

“…Based on our newly obtained results, the reported distribution of Distichodus langi and Brycinus comptus is expanded. Indeed, D. langi was described from the Uele River, a left bank affluent of the Ubangi (Middle Congo) (Nichols & Griscom, ), and was later also reported from the Aruwimi system (Decru et al ., ; Moelants et al ., ). A specimen recently collected in the mainstream of the Lower Lowa was assigned to that species (Abwe et al ., ).…”

“…'lowa'. Probably the species is widespread in the Congo basin as samples from the Ituri basin (Middle Congo basin), previously identified as B. kingsleyae Günther, 1896 (seeDecru et al, 2017), fell in the clade of the Lowa basin (Upper…”