@article {615, title = {Marcusenius elegans: a replacement name for Marcusenius gracilis Kramer 2013 (Osteoglossiformes: Mormyridae), a secondary junior homonym of Marcusenius senegalensis gracilis (Pellegrin 1922)}, volume = {5175}, year = {2022}, month = {Aug-18-2022}, pages = {499-500}, abstract = {

The West African mormyrid Marcusenius gracilis Kramer 2013 is a secondary homonym of Gnathonemus gracilis Pellegrin 1922 when both species are placed in the same genus Marcusenius (International Code of Zoological Nomenclature, article 57.3). Marcusenius gracilis was first described by Kramer (2013: 123), based on a holotype and 16 paratypes from Ivory Coast, West Africa. The taxon was subsequently treated as a valid species of Marcusenius by Kramer \& Wink (2013: 2334), and by Fricke et al. (2022). Kramer (2013) was not aware of Gnathonemus gracilis Pellegrin 1922, which was originally described by Pellegrin (1922: 221), based on a specimen from the Gribingui River, Lake Chad basin, in today\’s Central African Republic. The holotype is extant (MNHN 1922-0023). The taxon was treated as a synonym of the West African species Marcusenius senegalensis (Steindachner 1870), but as a valid subspecies (Gosse 1984: 89, L\év\êque et al. 1991: 138). Marcusenius senegalensis gracilis (Pellegrin 1922) has precedence over Marcusenius gracilis Kramer 2013, and the latter must be renamed when both taxa are classified in genus Marcusenius. Marcusenius elegans nom. nov. is herein proposed as the replacement name for Marcusenius gracilis Kramer 2013. The new species epithet is based on the Latin word elegans, meaning elegant, referring to its slender body; the name is treated as an adjective.

}, issn = {1175-5334, 1175-5326}, doi = {10.11646/zootaxa.5175.4.8}, url = {http://dx.doi.org/10.11646/zootaxa.5175.4.8}, author = {Fricke, R. and Bernd Kramer} } @inbook {605, title = {Communication and Waveform Analysis in Weakly Electric Fishes With Special Emphasis on Mormyrids}, booktitle = {The Senses: A Comprehensive Reference}, year = {2020}, pages = {255-280}, publisher = {Elsevier}, organization = {Elsevier}, edition = {2nd}, abstract = {

The electric sense in fishes was discovered in the 1950s. African snoutfish (Mormyridae) and South American knifefishes (Gymnotiformes) generate electric fields for testing their environment by Active Electrolocation, and for communication. These fishes\’ electric organ discharges (EODs) are species-specific (or \–characteristic) pulses or continuous waves, and vary widely in waveform, duration (frequency) and strength. In mormyrids the sequence (or pattern) of pulse intervals carries motivational and species-specific information. In a natural hybrid species complex, choosy females of the parent species block a speciation reversal by their preference for conspecific EOD waveforms, and rejection of the hybrid form. Electrosensory discrimination thresholds appear adapted to the fine detail of the EOD pulse waveforms on a ms-scale, with spectral cues not required in Pollimyrus adspersus. In some mormyrid species, breeding males add a strong D.C. component to their EOD, which attracts females but also\ low-frequency sensitive catfish predators. In several species, specific EOD patterns, as well as loud vocalizing, accompany courtship and spawning. The larvaes\’ early EODs of long pulse duration and initially low rate is replaced by an adult short EOD in young juveniles; parental care is present in Pollimyrus species. Three syntopic species gave examples of conflictual and cooperative electrocommunication in a semi-natural environment. Eigenmannia, a wave gymnotiform fish, is highly phase sensitive to stimuli of 0 Hz frequency difference, which evoke a Jamming Avoidance Response (which is a frequency shift away from the stimulus). The strength of the JAR depends on the phase difference stimulus to EOD. At a sufficient frequency difference, trained, food-rewarded Eigenmannia discriminate waveforms by a temporal mechanism that does not require spectral cues. Eigenmannia is incapable of discriminating stimuli that are phase-locked at maintained frequency identity.

}, isbn = {9780128054093}, doi = {10.1016/b978-0-12-805408-6.00027-0}, url = {https://epub.uni-regensburg.de/43937/1/Kramer\%2C\%20The\%20Senses\%202020_corrected.pdf}, author = {Bernd Kramer} } @article {582, title = {Female choice by electric pulse duration: attractiveness of the males{\textquoteright} communication signal assessed by female bulldog fish, Marcusenius pongolensis (Mormyridae, Teleostei)}, journal = {Journal of Experimental Biology}, volume = {211}, year = {2008}, month = {Mar-06-2009}, pages = {1969 - 1977}, abstract = {

In adult males of the South African weakly electric bulldog fish, Marcusenius pongolensis, the duration of the electric organ discharge (EOD) increases with body size over lifetime. Although there is experimental support for intrasexual selection (male\–male competition) having shaped the males\&$\#$39; EOD pulse duration in evolution, nothing is known about intersexual selection, such as female choice. Playback of 25 natural male EODs of pulse duration varying from 320 \μs (close to the average female value) to 716\μ s, to eight female experimental subjects elicited approach, head butts and circling behaviour. The rate of head butts on the dipole electrode model increased significantly with stimulus pulse duration in seven out of eight experimental subjects. In ten experimental female subjects we contrasted the shortest playback pulse with simultaneous playback of one of four longer ones (424, 524, 628 and 716 \μs). Pooled responses for all experimental subjects were stronger for the dipole playing back the longer pulse in a pulse pair. The difference in the number of head butts (\Δhead butts) that were dealt the two dipoles per 60 s test session increased significantly with the difference in pulse duration (\Δpulse duration). The increase followed a significant linear trend (P\<0.0001). Similar results were obtained for \Δassociation time, \Δcircles with head butts, and\Δ circles without head butts. These results suggest that a male\&$\#$39;s reproductive success is enhanced by longer, i.e. more attractive EODs, and that both intra- and intersexual selection must have played a significant role in shaping the EOD of male M. pongolensis.

}, issn = {0022-0949}, doi = {10.1242/jeb.016949}, url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.016949https://syndication.highwire.org/content/doi/10.1242/jeb.016949}, author = {Machnik, P. and Bernd Kramer} } @article {581, title = {Electrosensory prey detection in the African sharptooth catfish, Clarias gariepinus (Clariidae), of a weakly electric mormyrid fish, the bulldog (Marcusenius macrolepidotus )}, year = {2000}, abstract = {

During their seasonal runs in the Okavango and other freshwater bodies in southern Africa, the sharptooth catfish, Clarias gariepinus, specialises on the bulldog, Marcusenius macrolepidotus, as its main prey. We examined whether the catfish can locate bulldogs by detecting their pulse-type electric organ discharges (EODs). The electrosensory threshold for single-cycle, monopolar square-wave pulses was exceedingly low (down to 13 \µVp\–p/cm for 4-ms pulses) in trained, food-rewarded sharptooth catfish (n=4), confirming the results of Lissmann and Machin who were, however, unable to identify a biological function. Other stimulus pulse waveforms (single-cycle, monopolar as well as bipolar sine-wave pulses) were also effective stimuli according to their spectral low-frequency energy contents (0\– 30 Hz). Male bulldogs display an EOD pulse approximately 10\× the duration of female EODs (\≈0.5 ms). The C. gariepinus threshold for field-recorded playbacks of a male bulldog EOD (of long duration) was 103 \µVp\–p/cm, whereas the brief female and juvenile EODs were not detected (using intensities of natural EODs). EODs of other mormyrids were detected when either monopolar or of long duration. Signal source amplitude increased linearly with standard length (SL) in bulldogs. Signal reach, as calculated from signal source amplitude and receiver sensitivity, is up to 150 cm for a large male bulldog (SL 27.5 cm), and 83 cm for a male that has just turned sexually mature (SL 12.6 cm). Therefore, most bulldogs eaten by catfish are probably male, in agreement with the size distribution of bulldogs found in catfish stomachs. These results suggest that sharptooth catfish rely heavily on their acute electrical sense during hunting, and an important function for electroreception in an African catfish has been identified.

}, doi = {10.1007/s002650000232}, url = {http://link.springer.com/10.1007/s002650000232}, author = {Hanika, S. and Bernd Kramer} } @article {570, title = {Phylogenetic relationships between eight African species of mormyriform fish (Teleostei, Osteichthyes): resolution of a cryptic species, and reinstatement of Cyphomyrus Myers, 1960}, journal = {Biochemical Systematics and Ecology}, volume = {24}, year = {1996}, pages = {275-290}, chapter = {275}, abstract = {

Phylogenetic relationships between seven elephantfish species from five genera (Mormyridae) that are endemic to southem Africa, and the Nile knifefish of the sister family, Gymnamhidae, were determined using biochemical genetic data, behaviour (the waveforms of the electric organ discharge), morphology, and habitat and food preferences. The results confirmed the existence of an undescribed species of Hippopotamyrus, and that H.ansorgii and H.discorhynchus are not congeners.These distinctions had been suggested by differences in electric organ discharge wavefonns and are here substantiated by morphological and genetic data. We recommend the reinstatement of Cyphomyrus discorhynchus (Peters, 1852). Genetic distance (D, Nei, 1972) values suggest confamilial genera (D average of 1.09 for all species studied, and 0.715 for southern African species), with the exception of the sympatric and congeneric species: H. ansorgii and H. sp. (D=0.423). Phylogenies based on morphological and electrophoretic data are congruent.

}, doi = {10.1016/0305-1978(96)00026-9}, url = {https://www.sciencedirect.com/science/article/pii/0305197896000269?via\%3Dihub}, author = {F. Herman van der Bank and Bernd Kramer} } @article {541, title = {Electric organ discharges of South African Marcusenius species (Teleostei: Mormyridae) and their effectiveness as indicators of local species diversity}, journal = {Zootaxa}, volume = {4200}, year = {2016}, month = {May-11-2018}, pages = {367}, abstract = {

Recent morphological and genetic studies have revealed two new species of snoutfish in South Africa, Marcusenius caudisquamatus and M. krameri, which had been confused with M. pongolensis, the South African bulldog fish. All known mormyriform fish are nocturnal and emit electric organ discharges (EODs) for communication that are characteristic for their species. This paper examines whether or not the EODs of these three closely-related South African species can be differentiated from each other. An EOD pulse of a bulldog fish consists of a head-positive phase P, followed by a head-negative phase N of short duration. We measured and compared six variables of the EOD pulse waveform for South African samples for the three species from different locations using MANOVA, ANOVA and Discriminant Analysis, with M. devosi from Kenya as an outgroup. The EOD waveforms, normalized to the same P-phase amplitude, varied significantly from each other in four variables, most strongly in the amplitude of the N phase and the duration of the P phase. In two species, M. devosi and M. krameri, there was no evidence of difference between sexes, in contrast to M. pongolensis and M. caudisquamatus whose male pulses were of longer duration. M. devosi and M. krameri were statistically significantly independent of each other and of any other group studied. By contrast, the M. pongolensis specimens from different locations showed a high degree of variability amongst each other, including significant separation, and overlap with M. caudisquamatus.

}, issn = {1175-5326}, doi = {10.11646/zootaxa.4200.310.11646/zootaxa.4200.3.2}, url = {http://biotaxa.org/Zootaxa/issue/view/zootaxa.4200.3}, author = {Bernd Kramer and Pholoshi A. Maake and Ofer Gon} } @article {496, title = {Marcusenius desertus sp. nov. (Teleostei: Mormyridae), a mormyrid fish from the Namib desert}, journal = {African Journal of Aquatic Science}, year = {2016}, month = {Jul-03-2016}, pages = {1 - 18}, abstract = {

We critically compared Marcusenius specimens from the mouth of the Cunene River on the Namibia/Angola border, a harsh desert environment on the Atlantic Ocean coast virtually devoid of aerial insects with aquatic larvae which are an important food item, with Marcusenius multisquamatus Kramer \& Wink, 2013 from the escarpment region of that same river, in a relatively rich and productive subtropical savannah environment. River mouth specimens were differentiated in morphology and electric organ discharges, as determined by ANOVA/MANOVA comparisons, principal component and discriminant analyses on morphological and electrophysiological characters, and genetics, including sequences of the mitochondrial cytochrome b gene, indicating reproductive isolation. Specimens from the river mouth differed from M. multisquamatus, their closest relatives, by having a shorter snout, a smaller eye diameter, and smaller nares separation. River mouth specimens were also differentiated from other, increasingly less-close relatives, such as M. altisambesi Kramer et al., 2007 from the Okavango River, Botswana, and from M. krameri Maake et al., 2014 from the Limpopo System, South Africa. We therefore designate the new species Marcusenius desertus sp. nov. for the Cunene River mouth population.

}, keywords = {ecology, electric organ discharges, genetic differentiation, morphology, phylogeography, speciation}, issn = {1608-5914}, doi = {10.2989/16085914.2015.1137855}, url = {http://www.tandfonline.com/doi/full/10.2989/16085914.2015.1137855}, author = {Bernd Kramer and F. Herman van der Bank and Michael Wink} }