Hippopotamyrus ansorgii species complex in the Upper Zambezi River System with a description of a new species, H. szaboi (Mormyridae)

• Published in: Zoologica scripta 2004-01, Vol.33 (1), p.1-18
• Main Authors: Kramer, Bernd, Van Der Bank, Herman, Wink, Michael
• Format: Article
• Language: English
• Subjects: Freshwater; Hippopotamyrus ansorgii
• ISSN: 0300-3256; 1463-6409
• DOI: 10.1111/j.1463-6409.2004.00132.x

Kramer, B., Van der Bank, & H., Wink, M. (2004) Hippopotamyrus ansorgii species complex in the Upper Zambezi River System with a description of a new species, H. szaboi (Mormyridae). — Zoologica Scripta, 33, 1–18. Specimens referable to Hippopotamyrus ansorgii sampled from the Upper Zambezi River System within Caprivi (Namibia) represent a complex of three species, two of which coexist in the Upper Zambezi River, and a third that inhabits a nearby river, the Kwando, with which the Zambezi has been connected during periods of flooding. All three are indistinguishable in terms of their general appearance, but differ consistently in electric organ discharges (EOD), morphology, and molecular genetic characters. All phenotypes display a monopolar, head‐positive EOD pulse with specific post‐ or prepotentials. For H. ansorgii from the Zambezi River (HaZ), pulse duration is less than 0.5 ms (down to 0.205 ms; N= 34); for the syntopic H. szaboi sp. n., it is greater than 0.6 ms (up to 1.8 ms at 10% peak amplitude; N= 19). The parapatric phenotype of H. ansorgii from the Kwando River (HaK) has pulses shorter than 0.215 ms (down to 0.105 ms; N = 36). All three members of the species complex may be distinguished from each other by 7−9 anatomical characters, analysed by manova. Based on 22 enzymes and proteins studied, the moderate to high Wright's fixation index and the significant (P