@article {672, title = {Review of the southern African slender stonebashers, genus Heteromormyrus Steindachner 1866 (Teleostei: Mormyridae), with description of six new species}, journal = {Journal of Fish Biology}, volume = {108}, year = {2025}, month = {Sep-17-2025}, abstract = {

Recent molecular studies have advanced our knowledge of the taxonomic diversity and generic placement of the slender stonebashers, previously placed in the genus Hippopotamyrus, in southern Africa. These fishes were recently transferred to the genus Heteromormyrus whose range encompasses the Kwanza, Kunene, Okavango, Zambezi, Pungwe and Buzi River systems in southern Africa, as well as the southern tributaries of the Congo River system. The present study builds on previous research that identified at least eight candidate species within the Heteromormyrus ansorgii species complex by providing formal descriptions for six new species and redescriptions of Heteromormyrus pauciradiatus and H. ansorgii s.s. The Kwanza River system is peculiar because it currently has five known species in this genus, some of which are co-distributed, whereas the other river systems have only one or two species in this genus. Two of the new species, Heteromormyrus dolichorhynchus sp. nov. and Heteromormyrus angusticaudata sp. nov., are endemic to the Kwanza River system. Heteromormyrus xanekweorum sp. nov. is confined to the Okavango River system, Heteromormyrus chilembwei sp. nov. occurs in the Ruo River (lower Zambezi River system), Heteromormyrus tangwenai sp. nov. is endemic to the Pungwe River system and Heteromormyrus ndauorum sp. nov. is endemic to the Buzi River system. Species in this genus exhibit high morphological similarity, but they can be separated by a combination of characters, including scale counts, dorsal- and anal-fin ray counts, vertebral counts, caudal peduncle depth, position of nostrils, head shape and variation in colour pattern. Taxonomic diversity within this genus is likely to be higher than currently known, and future studies, particularly in the Kwanza and upper Zambezi rivers, are anticipated to uncover additional new species.

}, keywords = {Diversity, freshwater, mormyrids, southern Africa, Taxonomy}, issn = {0022-1112, 1095-8649}, doi = {10.1111/jfb.70191}, url = {https://doi.org/10.1111/jfb.70191}, author = {Mutizwa, Tadiwa I. and Kadye, Wilbert T. and Bragan{\c c}a, Pedro H. N. and Chakona, Albert} } @article {644, title = {Trophic ecology of the African riverine elephant fishes (Mormyridae)}, volume = {14}, year = {2024}, month = {Aug-01-2024}, abstract = {

Multiple species of the elephant fishes (Mormyridae) commonly coexist in sympatry in most African tropical rivers and lakes. In this study, we investigated the trophic ecology and potential trophic niche partitioning of eleven mormyrid fish species from the Sanaga River system in Cameroon using the stable isotope composition of carbon and nitrogen in the muscle samples. Albeit most mormyrids mainly feed on invertebrates, we found differences in isotope ratios, and we report signs of the trophic niche partitioning among species. We further found significant differences in isotopic signatures within the Mormyrus genus, suggesting ecological niche diversification among three closely related species. We have also evaluated differences in the isotopic signals between seasons in four species, which could be possibly caused by species migration and/or anthropogenic agricultural activities. To evaluate body shape, we applied geometric morphometric analyses, and we show that most of the species are clearly morphologically separated. We focused on the mormyrid ecomorphology to identify a possible interaction between shape and ecology, and we found a relationship between the \δ13C (but not \δ15N) isotopic signal and morphology, suggesting their interplay during mormyrid evolution. Overall, we present robust evidence of the trophic niche partitioning within the mormyrid species community, and we integrate trophic ecology with morphometrics, shedding light on the enigmatic evolutionary history of these fascinating African fishes.

}, keywords = {mormyrids, stable isotopes, trophic ecology, trophic position, trophic resource portioning}, issn = {2045-7758, 2045-7758}, doi = {10.1002/ece3.70173}, url = {http://dx.doi.org/10.1002/ece3.70173}, author = {Sommer, Gina Maria and Njom, Samuel Didier and Indermaur, Adrian and Nyom, Arnold Roger Bitja and Jandov{\'a}, Kate{\v r}ina and Kukla, Jaroslav and Petrt{\'y}l, Miloslav and Hork{\'a}, Petra and Musilova, Zuzana} } @article {617, title = {Karyotype of a Nigerian population of Hyperopisus bebe (Osteoglossiformes: Mormyridae) revealed another evolutionary lineage in the monospecific genus: Hyperopisus}, journal = {Ife Journal of Science }, volume = {24}, year = {2022}, month = {20 October 2022}, pages = {361-370}, chapter = {361}, abstract = {

This study provides data on the gross chromosome morphology, including centromeric and silver nitrate banding of a Nigerian population of Hyperopisus bebe, sampled from Asejire Reservoir, Osun River basin. The chromosomes of the fish samples were extracted using the Giemsa staining technique, and the centromeric and silver nitrate bandings were analyzed based on standard cytogenetic methods. The H. bebe population had a chromosome number of 2n = 40 and a karyotype formula of 2n = 40 (24m+6sm+10st/a), FN = 70. C-bands were restricted to the centromeric regions, suggesting that Robertsonian events are the major mechanism in the karyotype evolution in the population. Currently, H. bebe represents the only species in the genus Hyperopisus. The karyomorph data from this study suggest that the fish sample belongs to another species. However, other systematic approaches are needed to establish its taxonomic status.

}, keywords = {Chromosome rearrangements, Cytogenetics, karyomorphs, mormyrids, Robertsonian events}, doi = {10.4314/ijs.v24i2.15}, url = {https://www.ajol.info/index.php/ijs/article/view/233919}, author = {Jegede, OI} } @article {543, title = {Intragenus (Campylomormyrus) and intergenus hybrids in mormyrid fish: physiological and histological investigations of the electric organ ontogeny}, journal = {Journal of Physiology-Paris}, year = {2017}, month = {Jan-01-2017}, abstract = {

African weakly electric mormyrid fish show a high diversity of their electric organ discharge (EOD) both across and within genera. Thanks to a recently developed technique of artificial reproduction in mormyrid fish, we were able to perform hybridizations between different genera and within one genus (Campylomormyrus). The hybrids of intergenus hybridizations exhibited different degrees of reduced survival related to the phylogenetic distance of the parent species: hybrids of the crosses between C. rhynchophorus and its sister genus Gnathonemus survived and developed normally. Hybrids between C. rhynchophorus and a Mormyrus species (a more basal clade compared to Campylomormyrus s) survived up to 42 days and developed many malformations, e.g., at the level of the unpaired fins. Hybrids between C. numenius and Hippopotamyrus pictus (a derived clade, only distantly related to Campylomormyrus) only survived for two days during embryological development. Seven different hybrid combinations among five Campylomormyrus species (C. tamandua, C. compressirostris, C. tshokwe, C. rhynchophorus, C. numenius) were performed. The aim of the hybridizations was to combine species with (1) either caudal or rostral position of the main stalk innervating the electrocytes in the electric organ and (2) short, median or long duration of their EOD. The hybrids, though they are still juveniles, show very interesting features concerning electrocyte geometry as well as EOD form and duration: the caudal position of the stalk is prevailing over the rostral position, and the penetration of the stalk is dominant over the non-penetrating feature (in the Campylomormyrus hybrids); in the hybrid between C. rhynchophorus and Gnathonemus petersii it is the opposite. When crossing species with long and short EODs, it is always the long duration EOD that is expressed in the hybrids. The F1-Hybrids of the cross C. tamandua x C. compressirostris are fertile: viable F2-fish could be obtained with artificial reproduction

}, keywords = {Artificial reproduction, Campylomormyrus, Electric organ ontogeny, Hybrids, mormyrids}, issn = {09284257}, doi = {10.1016/j.jphysparis.2017.01.003}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425717300037}, author = {Frank Kirschbaum and Nguyen, Linh and Baumgartner, Stephanie and Chi, Linda and Wolfart, Rene and Elarbani, Khouloud and Eppenstein, Hari and Korniienko, Yevheniia and Guido-B{\"o}hm, Lilian and Victor Mamonekene and Vater, Marianne and Ralph Tiedemann} } @article {464, title = {Notes on the electric organ discharges (EODs) of four Mormyrus-species (Osteoglossomorpha: Mormyridae) from the Nilo-Sahelo-Sudan ichthyofaunal province of Africa}, journal = {Cybium}, volume = {39}, year = {2015}, month = {05/2015}, pages = {3{\textendash}10}, chapter = {3}, abstract = {

Field studies on the electric organ discharges (EODs) of Mormyrus species are rare, likely due to their biology hindering live capture in large numbers. Here the EODs of four Nilo-Sahelo-Sudanic species, Mormyrus caschive Linnaeus, 1758, M. kannume Forssk\ål, 1775, M. hasselquistii Valenciennes, 1847 and M. rume Valenciennes,1847, are compared and discussed. Their discharges are largely equal to each other, mainly showing differences in length and peak of Fourier transformation with less pronounced differences in the relative amplitude of phases within an EOD. The discharge properties allow species discrimination, at least within eco-regions, and thus likely play a role in species recognition.

}, keywords = {electric organ discharge, EODs, mormyrids, Mormyrus}, url = {http://www.researchgate.net/profile/Timo_Moritz/publication/276247346_Notes_on_the_electric_organ_discharges_(EODs)_of_four_Mormyrus-species_(Osteoglossomorpha_Mormyridae)_from_the_Nilo-Sahelo-Sudan_ichthyofaunal_province_of_Africa/links/5553180908ae6943a}, author = {Moritz, T.} }