Multiple independent colonizations into the Congo Basin during the continental radiation of African Mastacembelus spiny eels

AIM: There has been recent interest in the origin and assembly of continental biotas based on densely sampled species-level clades, however, studies from African freshwaters are few so that the commonality of macroevolutionary patterns and processes among continental clades remain to be tested. Within the Afrotropics, the Congo Basin contains the highest diversity of riverine fishes, yet it is unclear how this fauna was assembled. To address this, and the diversification dynamics of a continental radiation, we focus on African Mastacembelus spiny eels. LOCATION: Afrotropical freshwaters. METHODS: The most complete molecular phylogeny to date was reconstructed for African spiny eels. Divergence times were estimated applying a Bayesian relaxed clock comparing fossil and geological calibrations across nuclear and mitochondrial trees. Biogeographic reconstructions, applying a dispersal–extinction–cladogenesis model and lineage diversification dynamics were examined. RESULTS: Spiny eels originated in Asia and colonized Africa c. 15.4 Ma (95% HPD: 23.9–8.8 Ma) from which their subsequent radiation across the Afrotropics was best fitted by a constant rate model. Ancestral state estimation identified multiple colonization events into the Congo Basin, whereas all other regions were likely to have been colonized once indicating considerable geographic constraints. Application of the fossil calibration gave similar age estimates across datasets, whereas a geological calibration estimated considerably older nuclear divergences. MAIN CONCLUSIONS: Despite profound environmental events during the evolutionary history of the group, there is no evidence for rapid lineage diversification. This finding supports several recent studies on tropical continental radiations that contrast to the common pattern of density-dependent diversification. We further show that dispersal has occurred into, as well as out of the Congo Basin, indicating the importance of this region in the generation of biodiversity

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. 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 Onchob-della 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.Peer reviewe

The identity of Barbus capensis Smith, 1841 and the generic status of southern African tetraploid cyprinids (Teleostei, Cyprinidae)

The identity of Barbus capensis, as described by Andrew Smith (1841), is reviewed following a careful examination of the lectotype in the Natural History Museum, London. Evidence shows clearly that it represents a specimen of the Berg-Breede River whitefish or ‘witvis’ and not the species known as the Clanwilliam yellowfish, to which it was attributed until recently. The original illustration of the species is shown to be a composite of these two different species. A replacement name for the Clanwilliam yellowfish is drawn from the earliest described synonym, Labeobarbus seeberi (Gilchrist & Thompson, 1913). Following widespread recognition that the genus Barbus Daudin, 1805 does not occur in sub-Saharan Africa, the generic status of the Berg-Breede River whitefish (witvis) and other tetraploid cyprinines of southern Africa is reviewed, taking genetic and morphological characters into account. Five distinct lineages, each representing a genus, are recognized, including the genera Pseudobarbus Smith, 1841 and Cheilobarbus Smith, 1841, and three new genera described herein: Amatolacypris gen. nov., Sedercypris gen. nov. and Namaquacypris gen. nov

The identity of Barbus capensis Smith, 1841 and the generic status of southern African tretraploid cyprinids (Teleostei, Cyprinidae)

The identity of Barbus capensis, as described by Andrew Smith (1841), is reviewed following a careful examination of the lectotype in the Natural History Museum, London. Evidence shows clearly that it represents a specimen of the Berg-Breede River whitefish or ‘witvis’ and not the species known as the Clanwilliam yellowfish, to which it was attributed until recently. The original illustration of the species is shown to be a composite of these two different species. A replacement name for the Clanwilliam yellowfish is drawn from the earliest described synonym, Labeobarbus seeberi (Gilchrist & Thompson, 1913). Following widespread recognition that the genus Barbus Daudin, 1805 does not occur in sub-Saharan Africa, the generic status of the Berg-Breede River whitefish (witvis) and other tetraploid cyprinines of southern Africa is reviewed, taking genetic and morphological characters into account. Five distinct lineages, each representing a genus, are recognized, including the genera Pseudobarbus Smith, 1841 and Cheilobarbus Smith, 1841, and three new genera described herein: Amatolacypris gen. nov., Sedercypris gen. nov. and Namaquacypris gen. nov

Disentangling the Diversity of the <i>Labeobarbus</i> Taxa (Cypriniformes: Cyprinidae) from the Epulu Basin (DR Congo, Africa)

In an attempt to disentangle the complex taxonomy of the Labeobarbus species of the Epulu River, a right bank headwater affluent of the Aruwimi, Central Congo basin, a morphological study was undertaken on 221 specimens from the Epulu and 32 type specimens. As a result, five different species have been distinguished, including four so-called rubberlips, L. caudovittatus, L. macroceps, L. mawambiensis, and L. sp. ‘thick lip’, and one chiselmouth, L. longidorsalis. While rubberlips have a curved mouth with well-developed lips and often a mental lobe, chiselmouths have a straight mouth with a keratinised cutting edge on the lower jaw. Among the specimens examined, several presented an intermediate mouth morphology between L. mawambiensis and L. longidorsalis, either with one or two pairs of barbels. One specimen exhibited an intermediate morphology between L. mawambiensis and L. macroceps. This morphological study, complemented with a molecular study of the mitochondrial gene cytochrome b (cyt b), suggests that these intermediates are probably hybrid specimens. The Epulu case is reminiscent to a case of possible hybridisation recently discovered in the Inkisi River (Lower Congo basin), but differs in having a lower relative abundance of hybrid specimens in the population, and in phylogenetic patterns

Disentangling the Diversity of the Labeobarbus Taxa (Cypriniformes: Cyprinidae) from the Epulu Basin (DR Congo, Africa)

In an attempt to disentangle the complex taxonomy of the Labeobarbus species of the Epulu River, a right bank headwater affluent of the Aruwimi, Central Congo basin, a morphological study was undertaken on 221 specimens from the Epulu and 32 type specimens. As a result, five different species have been distinguished, including four so-called rubberlips, L. caudovittatus, L. macroceps, L. mawambiensis, and L. sp. &lsquo;thick lip&rsquo;, and one chiselmouth, L. longidorsalis. While rubberlips have a curved mouth with well-developed lips and often a mental lobe, chiselmouths have a straight mouth with a keratinised cutting edge on the lower jaw. Among the specimens examined, several presented an intermediate mouth morphology between L. mawambiensis and L. longidorsalis, either with one or two pairs of barbels. One specimen exhibited an intermediate morphology between L. mawambiensis and L. macroceps. This morphological study, complemented with a molecular study of the mitochondrial gene cytochrome b (cyt b), suggests that these intermediates are probably hybrid specimens. The Epulu case is reminiscent to a case of possible hybridisation recently discovered in the Inkisi River (Lower Congo basin), but differs in having a lower relative abundance of hybrid specimens in the population, and in phylogenetic patterns

Figure 7 in The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history

Figure 7. Diagram illustrating chronological changes in species numbers for Labeobarbus, sensu Tsigenopoulos et al. (2010) and Berrebi et al. (2014), in Africa. All numbers are provided per decade. For this diagram, all species have been attributed to Labeobarbus although many of them have originally been described in other genera in use at the time of their original description. The two species of the monospecific genera Acapoeta and Sanagia have been included in these counts. Nomina nuda are not included in the counts, as they are unavailable for nomenclatural purposes. A preoccupied name is counted as +1 by its original description and replaced (−1) by its replacement name (+1) at the date of replacement. No distinction has been made between species or subspecies descriptions, and as such both have been counted as +1 at the time of their original description. Giving both equal weighting gives a better overview of overall taxonomic activity in the genus as currently recognized. As nowadays none of the valid species, except for the West African and Nilotic Labeobarbus bynni and the East African Labeobarbus intermedius (see annotated checklist 2), is considered to contain subspecies, all previously described subspecies have been considered as formally synonymized, which translates into −1 for each, at the date of the first publication formally rejecting or instead clearly neglecting them. As such, of course, a change from subspecies to species level is not visible, and neither is the reverse; however, what has been made visible is the synonymization of subspecies with other subspecies or with the valid species.Published as part of &lt;i&gt;Vreven, Emmanuel J. W. M. N., Musschoot, Tobias, Snoeks, Jos &amp; Schliewen, Ulrich K., 2016, The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history, pp. 231-305 in Zoological Journal of the Linnean Society 177 (2)&lt;/i&gt; on page 268, DOI: 10.1111/zoj.12366, &lt;a href="http://zenodo.org/record/10109527"&gt;http://zenodo.org/record/10109527&lt;/a&gt

Figure 5 in The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history

Figure 5. Schematic illustration of the ventral side of the head of: A, Labeobarbus somereni; B, Labeobarbus alluaudi – tentatively identified as an intergeneric hybrid between L. somereni and Varicorhinus ruwenzorii (now Labeobarbus ruwenzorii); C, L. ruwenzorii (from Banister, 1972: figs 2, 10, 12).Published as part of &lt;i&gt;Vreven, Emmanuel J. W. M. N., Musschoot, Tobias, Snoeks, Jos &amp; Schliewen, Ulrich K., 2016, The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history, pp. 231-305 in Zoological Journal of the Linnean Society 177 (2)&lt;/i&gt; on page 248, DOI: 10.1111/zoj.12366, &lt;a href="http://zenodo.org/record/10109527"&gt;http://zenodo.org/record/10109527&lt;/a&gt

Figure 2 in The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history

Figure 2. Reproduction of the original illustration of: A, Labeobarbus nedgia (from Rüppell, 1835: plate 2, fig. 3); B, Varicorhinus beso (from Rüppell, 1835: plate 3, fig. 2) type species of Labeobarbus and Varicorhinus, respectively (both drawings flipped horizontally).Published as part of &lt;i&gt;Vreven, Emmanuel J. W. M. N., Musschoot, Tobias, Snoeks, Jos &amp; Schliewen, Ulrich K., 2016, The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history, pp. 231-305 in Zoological Journal of the Linnean Society 177 (2)&lt;/i&gt; on page 237, DOI: 10.1111/zoj.12366, &lt;a href="http://zenodo.org/record/10109527"&gt;http://zenodo.org/record/10109527&lt;/a&gt

Labeobarbus Vreven, Musschoot, Snoeks & Schliewen, 2016, S.L.

AFRICAN NOMINAL LABEOBARBUS &lt;i&gt;S.L.&lt;/i&gt; SPECIES IDENTIFIED AS HYBRID PHENOTYPES: LIST OF EXAMINED SPECIMENS &lt;p&gt; &lt;i&gt;alluaudi&lt;/i&gt;, &lt;i&gt;Barbus&lt;/i&gt; Pellegrin, 1909. Syntypes: MNHN 1909-0586 (1), 1909-0587 (1). &ndash; &lt;i&gt;microbarbis&lt;/i&gt;, &lt;i&gt;Barbus&lt;/i&gt; David &amp; Poll, 1937. Holotype: MRAC 41847. Paratypes: MRAC 41848&ndash;49 (2). &ndash; &lt;i&gt;microterolepis&lt;/i&gt;, &lt;i&gt;Barbus&lt;/i&gt; Boulenger, 1902. Holotype: BMNH 1902.12.13.220.&lt;/p&gt;Published as part of &lt;i&gt;Vreven, Emmanuel J. W. M. N., Musschoot, Tobias, Snoeks, Jos &amp; Schliewen, Ulrich K., 2016, The African hexaploid Torini (Cypriniformes: Cyprinidae): review of a tumultuous history, pp. 231-305 in Zoological Journal of the Linnean Society 177 (2)&lt;/i&gt; on page 305, DOI: 10.1111/zoj.12366, &lt;a href="http://zenodo.org/record/10109527"&gt;http://zenodo.org/record/10109527&lt;/a&gt