Marked differentiation in a new species of dwarf stonebasher, Pollimyrus cuandoensis sp. nov. (Mormyridae: Teleostei), from a contact zone with two sibling species of the Okavango and Zambezi rivers

Abstract

We studied the systematic status of a form of Pollimyrus of the lower Kwando River that is flanked by the Okavango River, inhabited by Pollimyrus castelnaui (Boulenger, 1911), and the Zambezi River, inhabited by Pollimyrus marianne Kramer et al., 2003. In morphology and electric organ discharges (EODs), the Kwando phenotype proved well differentiated from both P. castelnaui and P. marianne. Sequence analysis of the cyt b gene confirmed that the three forms or species form a monophyletic clade, with P. castelnaui sister to the other two species. Genomic fingerprinting with ISSR-PCR confirmed differentiation of the Kwando form, that we recognize as a different species, P. cuandoensis sp. nov., from its sister species, P. marianne. A considerable amount of EOD and morphological variation was revealed among samples of P. cuandoensis sp. nov. from four different locations on the lower Kwando River, possibly due to hybrid introgression. This seems an ideal system for testing theories of parapatric speciation. http://www.zoobank.org/urn:lsid:zoobank.org:pub:FB644B21-04F6-44F8-AEB6-8DC09268C17C

Keywords:

• speciation
• parapatric
• cline
• hybridization
• electric organ discharge
• DNA sequence analysis
• genomic fingerprinting

Acknowledgements

For assistance in the field, we thank Bianca Hitha (RAU) and the late Johan Engelbrecht (Mpumalanga Parks Board). For morphological data acquisition we thank: Kathrin Kahler, Thomas Gierl, Birgit Blaul, Sabine Hartl, Lena Dietz, Martina Lange, Ellen Fröhlich, and Silvia Förster and for DNA sequencing Hedi Sauer-Gürth (IPMB). We thank Ernst Ardelean, Klaus Heine and Ellen Fröhlich for various stages of Figure 1, Ellen Fröhlich for Figure 2. Supported by DFG grant no. KR 446/12-2 and previous grants.