@article {215, title = {Intraspecific variability of the pulse-type discharges of the African electric fishes, Pollimyrus isidori and Petrocephalus bovei (Mormyridea, Teleostei), and their dependence on water conductivity.}, journal = {Experimental Biology}, volume = {47}, year = {1988}, pages = {227-238}, author = {Bratton, B.O. and Bernd Kramer} } @article {879, title = {Evidence for parapatric speciation in the mormyrid fish, Pollimyrus castelnaui (Boulenger, 1911) from the Okavango-Upper Zambezi River systems: P. marianne sp. nov., defined by electric organ discharges, morphology and genetics}, journal = {Environmental Biology of Fishes}, volume = {67}, year = {2003}, pages = {47 - 70}, abstract = {

We report on parapatric speciation in the mormyrid fish,Pollimyrus castelnaui (Boulenger, 1911), from the Okavango and the Upper Zambezi River systems. We recognise samples from the Zambezi River as a distinct species, P. marianne, displaying an eastern phenotype of electric organ discharge (EOD) waveform (Type 3) that is distinct from the western EOD phenotype (Type 1) observed in P. castelnaui samples from the neighbouring Okavango. Samples from the geographically intermediate Kwando/Linyanti River (a tributary of the Zambezi that is also intermittently connected to the Okavango) presented a more variable third EOD phenotype (Type 2). In 13 out of 14 morphological characters studied, the Zambezi River samples differed significantly from P. castelnaui. Morphologically and in EOD characters, the Kwando/Linyanti fish are distinct from both P. castelnaui and P. marianne. Sequence analysis of the mitochondrial cytochrome b gene unambiguously reveals that specimens from the Zambezi River System form a well supported taxon which clearly differs from P. castelnaui from the Okavango (1.5\–2.5\% sequence divergence).Within specimens from theKwando\–Zambezi System some geographic differentiation can be detected (nucleotide substitutions up to 0.6\%); but groups cannot be resolved with certainty. Significant allozyme differences were found between the Okavango and all other EOD types from the Upper Zambezi System, and, within the Zambezi System, between the Kwando (Type 2) and Zambezi (Type 3) individuals. The low Wright\’s fixation index values, the lack of fixed allele differences, and small genetic distances provide little evidence for speciation between groups within the Zambezi System, but moderate to great fixation index values and significant allele frequency differences were observed between the Okavango and the other fishes. It is concluded that within the Zambezi System, differentiation between Kwando/Linyanti and Zambezi populations (as revealed by morphology and EOD waveform comparisons) is so recent that substantial genetic (allozyme and mitochondrial sequence) differences could not have evolved, or were not detected.

}, issn = {03781909}, doi = {10.1023/A:1024448918070}, author = {Bernd Kramer and F. Herman van der Bank and Flint, Nicolette and Sauer-G{\"u}rth, Hedi and Michael Wink} } @article {425, title = {The southern churchill, Petrocephalus wesselsi, a new species of mormyrid from South Africa defined by electric organ discharges, genetics, and morphology}, journal = {Environmental Biology of Fishes}, volume = {59}, year = {2000}, pages = {393-413}, author = {Bernd Kramer and F. Herman van der Bank} } @article {352, title = {Electric signalling and reproductive behaviour in a mormyrid fish, the bulldog Marcusenius macrolepidotus (South African form)}, journal = {Journal of Ethology}, volume = {23}, year = {2005}, month = {7/2005}, pages = {113 - 125}, issn = {1439-5444}, doi = {10.1007/s10164-004-0136-0}, author = {Werneyer, Martin and Bernd Kramer} } @article {351, title = {Electrosensory basis for individual recognition in a weakly electric, mormyrid fish, Pollimyrus adspersus (G{\"u}nther, 1866)}, journal = {Behavioral Ecology and Sociobiology}, volume = {55}, year = {2003}, month = {12/2003}, pages = {197 - 208}, issn = {1432-0762}, doi = {10.1007/s00265-003-0690-4}, author = {Paintner, Stephan and Bernd Kramer} } @article {350, title = {Allopatric differentiation in the acoustic communication of a weakly electric fish from southern Africa, Marcusenius macrolepidotus (Mormyridae, Teleostei)}, journal = {Behavioral Ecology and Sociobiology}, volume = {61}, year = {2006}, month = {12/2006}, pages = {385 - 399}, abstract = {

A few species of the weakly electric snoutfish, the African freshwater family Mormyridae, have been reported to vocalise. However, allopatric populations of a single species were never compared. Members of three allopatric Marcusenius macrolepidotus populations, originating from the Upper Zambezi River in Namibia, the Buzi River (Mozambique), and the Incomati River system in South Africa, vocalised with pulsatile growl- and tonal hoot sounds in dyadic confrontation experiments. A high rate of growling accompanied territorial and agonistic interactions and also non-threatening interactions between males and females, which in one pair appeared to be courtship. Growl sound characteristics of M. macrolepidotus from the Incomati system differed from those of the Upper Zambezi in a significantly higher frequency of the first harmonic (mean, 355 Hz vs 266 Hz). The two vocalising males from the Buzi River generated growls about twice as long as the other fish. Furthermore, the growl pulse period was about 4 ms in M. macrolepidotus from the Upper Zambezi River and from the Incomati system, but 6 ms in M. macro- lepidotus from the Buzi River. Hoots were only observed in agonistic encounters. Hoot oscillograms showed a sinusoi- dal waveform, and the mean duration of this sound was similar in Incomati system fish (mean, 161 ms), Upper Zambezi fish (172 ms) and Buzi fish (103 and 145 ms for\ the two vocalising individuals). The mean frequency of the first hoot harmonic was higher in Incomati system fish (326 Hz) than in Upper Zambezi fish (245 Hz). Both growl and hoot occurred only in the presence of conspecifics, probably signalling the presence and condition of an opponent, territory owner or potential mate. This is the first evidence for (1) sound production and acoustical commu- nication in another species and genus, M. macrolepidotus, from southern Africa to be (2) geographically differentiated.

}, issn = {1432-0762}, doi = {10.1007/s00265-006-0267-0}, author = {Lamml, Michael and Bernd Kramer} } @article {402, title = {Hippopotamyrus ansorgii species complex in the Upper Zambezi River System with a description of a new species, H. szaboi (Mormyridae)}, journal = {Zoologica Scripta}, volume = {33}, year = {2004}, month = {01/2004}, pages = {1 - 18}, issn = {1463-6409}, doi = {10.1111/j.1463-6409.2004.00132.x}, author = {Bernd Kramer and F. Herman van der Bank and Michael Wink} } @article {202, title = {Allopatric differentiation in the Marcusenius macrolepidotus species complex in southern and eastern Africa: the resurrection of M. pongolensis and M. angolensis, and the description of two new species (Mormyridae, Teleostei)}, journal = {Journal of Natural History}, volume = {41}, number = {9-12}, year = {2007}, pages = {647-708}, doi = {10.1080/00222930701250987}, author = {Bernd Kramer and P. Skelton and F. Herman van der Bank and Michael Wink} } @inbook {355, title = {Electric Communication and Electrolocation}, booktitle = {Encyclopedia of Neuroscience}, year = {2009}, pages = {1038 - 1045}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {978-3-540-29678-2}, doi = {10.1007/978-3-540-29678-2_2913}, author = {Bernd Kramer}, editor = {Binder, Marc D. and Hirokawa, Nobutaka and Windhorst, Uwe} } @article {349, title = {A new species of Slender Stonebasher within the Hippopotamyrus ansorgii complex from the Cunene River in southern Africa (Teleostei: Mormyriformes)}, journal = {Journal of Natural History}, volume = {44}, year = {2010}, month = {9/2010}, pages = {2213 - 2242}, issn = {0022-2933}, doi = {10.1080/00222931003764089}, author = {Bernd Kramer and Ernst Swartz} } @article {642, title = {The Victoria Falls, a species boundary for the Zambezi Parrotfish, Cyphomyrus discorhynchus (Peters, 1852), and the resurrection of Cyphomyrus cubangoensis (Pellegrin, 1936) (Mormyridae: Teleostei)}, journal = {Journal of Natural History}, volume = {45}, number = {43-44}, year = {2011}, abstract = {

Cyphomyrus discorhynchus occurs in the Zambezi River and in the linked systems of the Kwando and the Okavango. We collected specimens from both above and below the Victoria Falls and recorded Electric Organ Discharges. We found a marked degree of anatomical differentiation among the specimens from the Zambezi delta to the Victoria Falls that represents a subspecific, geographical cline, reflecting the great length (1400 km) and high ecological diversity of that river section (Lower and Middle Zambezi). We confirm that the populations above the Falls (i.e. Upper Zambezi, Kwando and Okavango) are differentiated from those below, possessing fewer dorsal fin rays (a median of 30-31 rather than 33-34). The waveforms of the electric organ discharge pulses have four phases and show geographic variation but were briefer for specimens from below the Falls. We resurrect Cyphomyrus cubangoensis (Pellegrin, 1936) for the Upper Zambezi/Kwando/Okavango system

}, author = {Bernd Kramer and F. Herman van der Bank} } @article {1822, title = {A critical revision of the churchill snoutfish, genus Petrocephalus Marcusen, 1854 (Actinopterygii: Teleostei: Mormyridae), from southern and eastern Africa, with the recognition of Petrocephalus tanensis, and the description of five new species}, journal = {Journal of Natural History}, volume = {46}, year = {2012}, month = {09/2012}, pages = {2179{\textendash}2258}, abstract = {

We morphologically and genetically studied the southern African electric fish Petrocephalus catostoma, or churchill, and its six nominal species, five of which by synonymization (three valid subspecies). We reinstate the synonymized species, and recognize Petrocephalus tanensis (Whitehead and Greenwood, 1959) from the Tana River in Kenya, also using electric organ discharges. The Okavango delta (Botswana) is inhabited by Petrocephalus okavangensis sp. nov. and Petrocephalus magnitrunci sp. nov., and the Namibian Cunene River by Petrocephalus magnoculis sp. nov. We recognize Petrocephalus petersi sp. nov. for the Lower Zambezi River (Mozambique), and Petrocephalus longicapitis sp. nov. for the Upper Zambezi River (Namibia). The Lufubu River in Northern Zambia is inhabited by Petrocephalus longianalis sp. nov. For the southern churchill, Petrocephalus wesselsi Kramer and Van der Bank, 2000, we confirm intraspecific and interspecific differentia- tion. Sequence data from mitochondrial DNA confirm differentiation of two new western and two eastern species, forming mutual sister groups.

}, keywords = {allopatric speciation, electric organ discharges, molecular genetics, morphometrics, Systematics}, issn = {ISSN 0022-2933}, doi = {10.1080/00222933.2012.708452}, url = {http://dx.doi.org/10.1080/00222933.2012.708452}, author = {Bernd Kramer and Roger Bills and P. Skelton and Michael Wink} } @article {823, title = {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}, journal = {Journal of Natural History}, year = {2014}, month = {12/2013}, pages = {1 - 35}, issn = {1464-5262}, doi = {10.1080/00222933.2013.807950}, author = {Bernd Kramer and F. Herman van der Bank and Michael Wink} } @article {852, title = {Morphological and electrophysiological field observations on electric freshwater fish of the genus Mormyrops M{\"u}ller 1843 (Teleostei: Mormyridae) from West and southern Africa}, journal = {African Journal of Aquatic Science}, volume = {38}, year = {2013}, month = {11/2013}, pages = {31 - 41}, abstract = {

Different specimens of Mormyrops anguilloides (Linnaeus 1758) were reported to display electric organ discharge (EOD) pulses of either initially head-positive or initially negative polarity, a hypothetical sex difference that has not been substantiated to date. The morphology and EODs of M. anguilloides of both sexes and a sexually mature size from the Comoé and Bandama rivers, Côte d\’Ivoire, and the Lower and Middle Zambezi, Mozambique, displayed initially positive EODs. The morphologically similar M. breviceps Steindachner 1895 of both sexes and a sexually mature size from the Bandama River displayed initially head-negative EODs of biphasic waveform and long duration (0.93\–1.15 ms) in the very-low-frequency spectral range. Mormyrops anguilloides from the Comoé and Bandama rivers were differentiated in caudal peduncle depth and in EOD waveform, pulse duration and spectral energy content. The former samples displayed a biphasic, lower-frequency EOD pulse of up to 0.42 ms duration, the latter a tetraphasic, high-frequency EOD of up to 0.33 ms. It is suggested that reports of EODs of both polarities in M. anguilloides indicate the presence of an unrecognised species.

}, issn = {1727-9364}, doi = {10.2989/16085914.2013.791244}, url = {http://dx.doi.org/10.2989/16085914.2013.791244}, author = {Bernd Kramer} } @article {882, title = {Differentiation in morphology and electrical signalling in four species of para- and sympatric Marcusenius (Teleostei: Mormyridae) from C{\^o}te d{\textquoteright}Ivoire, West Africa}, journal = {Marine and Freshwater Behaviour and Physiology}, volume = {46}, year = {2013}, month = {03/2013}, pages = {105 - 133}, abstract = {

Marcusenius Gill, 1862 species were sampled from the Bandama River and the Comoé River in Côte d\’Ivoire, West Africa. Marcusenius gracilis sp. nov. was differentiated from M. senegalensis (Steindachner, 1870), Marcusenius ussheri (Günther, 1867) and M. furcidens (Pellegrin, 1920) in electric organ discharges (EOD), and morphologically from all other West African congeners. Principal component analysis showed significant morphological differentiation among the four Ivorian species. Principal component 1 was loaded most strongly by characters affecting swimming power and manoeuvrability. The morphologically most similar pair, M. furcidens and M. gracilis sp. nov., are distinguished by their EOD waveforms and a sexual dimorphism in the anal fin base in the latter not present in the former. M. ussheri is distinguished by a sexual dimorphism in its EOD waveform not observed in the other three species. This system is an opportunity to study how far the fine-tuning of char- acter displacement among syntopic species can go.

}, issn = {1029-0362}, doi = {10.1080/10236244.2013.796161}, author = {Bernd Kramer} } @article {876, title = {East{\textendash}west differentiation in the Marcusenius macrolepidotus species complex in Southern Africa: the description of a new species for the lower Cunene River, Namibia (Teleostei: Mormyridae)}, journal = {Journal of Natural History}, volume = {47}, year = {2013}, month = {09/2013}, pages = {2327 - 2362}, abstract = {

This paper critically compares the Southern African bulldog fish species Marcusenius macrolepidotus (Peters, 1852), inhabiting the eastern Lower Zambezi River, and Marcusenius altisambesi Kramer et al., 2007, inhabiting the central Upper Zambezi River, with bulldog fish samples from the western lower Cunene River, a 2600-km range from the Indian Ocean to the Atlantic. The three species or forms are well differentiated in morphology and molecular genetics, and dif- ferentiation is also present in electric organ discharges. Marcusenius altisambesi and the Cunene sample, which we recognize as Marcusenius multisquamatus sp. nov., are closely related and form a sister taxon to M. macrolepidotus. This result is based on the analysis of mitochondrial cytochrome b sequences and genomic Inter-simple-sequence-repeat fingerprinting. Morphological adaptations to life in a torrential escarpment river seem to be present in M. multisquamatus sp. nov. when compared with M. altisambesi, which lives in a reservoir river that periodi- cally floods the savannah.

}, issn = {1464-5262}, doi = {10.1080/00222933.2013.798699}, author = {Bernd Kramer and Michael Wink} }