A mismatch between morphological and molecular data in lineages of Enteromius (Cypriniformes: Cyprinidae) from the Lowa basin (East Democratic Republic of the Congo: DRC) with the description of a new species

Abstract

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.

http://zoobank.org/urn:lsid:zoobank.org:pub:D2263E5B-D403-404C-B66C-852215ED100C

Key words:

• Congo basin
• discordance
• Enteromius
• introgression
• lineage-based species
• morphospecies

Acknowledgements

This study was undertaken within the ‘Mbisa Congo I’ project, a framework agreement project of the RMCA (2013-2018) and finalized during the ‘Mbisa Congo II’ project (2019–2023), both financed by the Belgian Development Cooperation. TK benefitted from research grant (IFS no. A5787-1 2015-2017) of the International Foundation for Science. Boniface Kaningini Mwenyimali (ISP of Bukavu), Amundala Shekani and Masilya Mulungula Pascal (both CRH-Uvira) are acknowledged for their administrative assistance. We are grateful to Nathalie Smitz (RMCA) and Maarten Van Steenberge (RBINS) for assistance in the molecular lab, Alain Reygel (RMCA) for the drawings, Miguel Parrent and Baudouin Willy (both RMCA) for their collection management assistance; and Thibault Nève (RMCA), assistant in Mbisa Congo II for X-rays, pictures of pharyngeal jaws provided. Finally, we like to acknowledge Melanie Stiassny and Barbara Brown (both AMNH), Tom Geerinckx, Olivier Pauwels and Sebastien Bruaux (all at Institut Royal des Sciences Naturelles de Belgique, Bruxelles: IRSNB) for the loan of Enteromius specimens from the Kasai drainage under their care.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental Material

Supplementary material for this article can be accessed here: https://doi.org/10.1080/14772000.2022.2135630.

Associate Editor: Dr Kevin Conway