Electric organ discharges of South African Marcusenius species (Teleostei: Mormyridae) and their effectiveness as indicators of local species diversity

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 headnegative 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.

Electroreception, electrogenesis and electric signal evolution

“…Myers 1960 (Kramer & van der Bank, 2011), Marcusenius (Kramer, 2013a;Kramer et al, 2007Kramer et al, , 2016aKramer et al, , 2016bKramer & Wink, 2013),…”

“…e.g. Campylomormyrus (Feulner et al ., ; Feulner et al ., ; Lamanna et al ., ), Cyphomyrus Myers 1960 (Kramer & van der Bank, ), Marcusenius (Kramer, ; Kramer et al ., , , ; Kramer & Wink, ), Mormyrops (Kramer, ), Mormyrus (Kramer, ; Moritz, ), Paramormyrops (Arnegard et al ., , , ; Arnegard & Hopkins, ; Gallant et al ., ; Rich et al ., ; Sullivan et al ., ), Petrocephalus (Kramer et al ., ; Lavoué et al ., , ; Lavoué & Sullivan, ; Moritz et al ., ), Pollimyrus (Kramer et al ., ; Markowski et al ., ) and Stomatorhinus Boulenger 1898 (Sullivan & Hopkins, ).…”

Deep genetic and morphological divergence in the Hippopotamyrus ansorgii species complex (Teleostei: Mormyridae) in southern Africa

“…Southern Africa was previously assumed to have low diversity of mormyrid fishes, with only nine recognized species, which were all considered to have broad distribution ranges (Skelton, 2001). Nonetheless, over the past two decades, several integrative taxonomic studies in the region have shown that most mormyrid genera contain a number of species that were previously unknown to science (Kramer, 2013; Kramer et al ., 2003; Kramer et al ., 2004; Kramer et al ., 2007; Kramer et al ., 2012; Kramer et al ., 2016; Kramer & Swartz, 2010; Kramer & van der Bank, 2000; Kramer & van der Bank, 2011; Kramer & Wink, 2013; Maake et al ., 2014). These studies have led to the description of 17 new species and the resurrection of 1 species, indicating that mormyrid diversity in southern Africa remains underestimated.…”

“…studies in the region have shown that most mormyrid genera contain a number of species that were previously unknown to science (Kramer, 2013;Kramer et al, 2003;Kramer et al, 2004;Kramer et al, 2007;Kramer et al, 2012;Kramer et al, 2016;Kramer & Swartz, 2010;Kramer & van der Bank, 2000;Kramer & van der Bank, 2011;Kramer & Wink, 2013;Maake et al, 2014). These studies have led to the description of 17 new species and the resurrection of 1 species, indicating that mormyrid diversity in southern Africa remains underestimated.…”