04147nas a2200145 4500008004100000022002500041245012700066210007100193260001600264300000900280520363100289100002203920700002203942856003703964 2025 eng d a0022-3751, 1469-779300aHigh‐frequency electrical tuning and linear filter properties of Knollenorgan electroreceptors of mormyrid electric fish0 aHigh‐frequency electrical tuning and linear filter properties of cJun-15-2025 a1-223 a

Electrical tuning allows auditory, vestibular, and electrosensory receptor cells to filter sensory signals and selectively transmit specific stimulus frequencies. In auditory hair cells, electrical tuning results from membrane potential resonance produced by voltage‐gated Ca and K(Ca) channels, with variable kinetics that generate different tuning properties. Such resonance has been observed only up to ∼1 kHz, however. Additionally, in most species that employ electrical tuning, hearing is constrained to this relatively low‐frequency range, raising the question of whether electrical tuning can extend to higher frequencies. Here we investigated this possibility by studying tuning and transduction properties of Knollenorgans, a class of tuberous electroreceptors of mormyrid electric fish. These organs, which generate spike‐like receptor potentials, detect species‐specific electric organ discharges (EODs). To test whether fish with brief EODs had correspondingly high‐frequency electrical tuning, we recorded tuning curves from Knollenorgans of three species, Brevimyrus niger, Gnathonemus petersii, and Pollimyrus adspersus, which have EODs with spectral components exceeding 5 kHz. All species had receptors tuned to a range of frequencies tiling the species‐specific EOD spectrum, with best frequencies extending beyond 10 kHz in P. adspersus. We also computed the impulse response of each Knollenorgan by reverse‐correlating spikes elicited by white noise stimuli. After incorporation of a spike threshold non‐linearity, convolving the impulse response with arbitrary stimulus waveforms successfully predicted spike patterns experimentally evoked by these inputs. These analyses demonstrate that differential electrical tuning properties of Knollenorgans produce distinct, well‐timed spike responses that reliably encode time‐varying electrical signals at frequencies up to 20 kHz. imageKey points Knollenorgans, among the tuberous electroreceptors of mormyrid electric fish, are modified hair cells that transduce electrical signals into spike‐like receptor potentials. Knollenorgans in three species of mormyrids are tuned to frequencies matched to the frequencies present in the species‐typical electric organ discharges, suiting them for electric communication. The frequency of highest sensitivity of Knollenorgans can extend well beyond 10 kHz, far exceeding the limit for electrical tuning mechanisms estimated from mechanosensitive hair cells. The timing and probability of spiking by Knollenorgans are accurately predicted by a model composed of linear filtering followed by non‐linear rectification and spike thresholding. Differential filtering by different Knollenorgans produces distinct outputs to the same input, with high‐tuned receptors effectively transmitting well‐timed spikes, on a microsecond time scale, in response to electrical stimuli up to 20 kHz.

1 aRaman, Indira, M.1 aHopkins, Carl, D. uhttps://doi.org/10.1113/jp28829902463nas a2200157 4500008004100000022002500041245016500066210006900231260001600300520186800316100001602184700002202200700002202222700002102244856004002265 2023 eng d a0962-1083, 1365-294X00aDiet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus)—A hybrid capture/HTS metabarcoding approach0 aDiet in phenotypically divergent sympatric species of African we cDec-21-20233 a

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study documents the overall diet of the genus Campylomormyrus and examines the hypothesis that the Campylomormyrus radiation is caused by adaptation to different food sources. We performed diet assessment of five sympatric Campylomormyrus species (C. alces, C. compressirostris, C. curvirostris, C. tshokwe, C. numenius) and their sister taxon Gnathonemus petersii with markedly different snout morphologies and EODs using hybrid capture/HTS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, that is fauna at the bottom, the water surface and the water column. A major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results indicate that different snout morphologies and the associated divergence in the EOD could translate into different prey spectra. This suggests that the diversification in EOD and/or morphology of the feeding apparatus could be under functional adaptation.

1 aAmen, Rahma1 aHavenstein, Katja1 aKirschbaum, Frank1 aTiedemann, Ralph uhttp://dx.doi.org/10.1111/mec.1724801927nas a2200157 4500008004100000022001400041245006100055210006100116260001600177490000600193520147300199100001901672700001601691700002001707856004201727 2023 eng d a2517-484300aHistology of Convergent Probing Appendages in Mormyridae0 aHistology of Convergent Probing Appendages in Mormyridae cJan-01-20230 v53 a

Mormyridae is an early diverging family of Teleostean fishes that produce an electric field for navigation and communication using an electric organ. This clade has a diverse array of soft-tissue rostral appendages, such as the chin-swelling, the Schnauzenorgan, and the tubesnout combined with a Schnauzenorgan, that have evolved multiple times. Here we assess if macroscopically convergent, soft-tissue rostral appendages are also histologically convergent. Further, we investigate how the histology of these appendages can inform their function. We sampled independent gains of the chin-swelling and Schnauzenorgan to understand similarities and differences in their anatomies. We show that macroscopically convergent rostral appendages are also convergent at a histological level, and different types of rostral appendages share a similar anatomy; that said, minor differences likely relate to their specific functions. Based on a comparison of the skeletal muscle distribution and the differing attachment shapes of each appendage to the dentary, we conclude that the Schnauzenorgan is capable of a wider range of movements than the chin swelling. Furthermore, the anatomy suggests that these soft-tissue rostral appendages likely function as electrosensory foveas (i.e., an appendage that focuses a sensory system). Lastly, these histological data support the hypothesis that the chin swelling may be a precursor to the Schnauzenorgan.

1 aPeterson, Rose1 aEvans, A, J1 aHernandez, L, P uhttp://dx.doi.org/10.1093/iob/obad00101771nas a2200217 4500008004100000022001400041245006900055210006500124260001600189300001000205490000800215520117700223653001701400653001601417653000801433653001701441100001701458700001701475700002001492856004101512 1976 eng d a0302-982400aThe electric organ of a mormyrid as a current and voltage source0 aelectric organ of a mormyrid as a current and voltage source cJan-01-1976 a65-880 v1103 a

We have examined how the electric organ discharge (EOD) of a mormyrid (Gnathonemus petersii) is affected by changes in resistive load (Figs. 3, 4, 5). We have also shown how this load depends on resistivity and distance to non-conducting boundaries (Figs. 10, 11). When resistive load was varied, voltage and current were related in a linear, battery-like manner for the initial, head positive phase of the EOD (Figs. 4, 5). This linear relation made it possible to estimate first phase e.m.f, and source resistance. For the second, head negative phase, however, voltage rose to a peak and then fell as resistance increased. Furthermore, the waveform of the second but not the first phase was strongly affected by load changes. These second phase features were shown to reflect a dependence of second phase e.m.f, on first phase current. A linear and battery-like relation between second phase voltage and current was seen when first phase load was held constant while varying second phase load (Fig. 6). These results on the behavior of the whole electric organ can be understood in terms of the underlying properties of the cellular generators, the electrocytes

10aconductivity10aelectrocyte10aEOD10aeod waveform1 aBell, C., C.1 aBradbury, J.1 aRussell, C., J. uhttp://dx.doi.org/10.1007/bf0065678201616nas a2200169 4500008004100000022001400041245015000055210006900205260001600274520099000290100002601280700002501306700002001331700002101351700002201372856005201394 2022 eng d a1432-135100aIntergenus F1-hybrids of African weakly electric fish (Mormyridae: Gnathonemus petersii ♂ × Campylomormyrus compressirostris ♀) are fertile.0 aIntergenus F1hybrids of African weakly electric fish Mormyridae  c2022 Feb 043 a

Hybridisation is an important element of adaptive radiation in fish but data are limited in weakly electric mormyrid fish in this respect. Recently, it has been shown that intragenus hybrids (Campylomormyrus) are fertile and are able to produce F2-fish. In this paper, we demonstrate that even intergenus hybrids (Gnathonemus petersii ♂ × Campylomormyrus compressirostris ♀) are fertile. Three artificial reproduction (AR) trials, with an average fertilisation rate of ca. 23%, yielded different numbers of survivals (maximally about 50%) of the F1-hybrids. The complete ontogenetic development of these hybrids is described concerning their morphology and electric organ discharge (EOD). Two EOD types emerged at the juvenile stage, which did not change up to adulthood. Type I consisted of four phases and Type II was triphasic. The minimum body length at sexual maturity was between 10 and 11 cm. Malformations, growth and mortality rates are also described.

1 aKorniienko, Yevheniia1 aNzimora, Kingsley, C1 aVater, Marianne1 aTiedemann, Ralph1 aKirschbaum, Frank uhttps://mormyrids.efishgenomics.com/fr/node/60800328nas a2200109 4500008004100000245003900041210003900080300002100119490000800140100001700148856005300165 1916 eng d00aDie Schnauzenorgane der Mormyriden0 aDie Schnauzenorgane der Mormyriden a650-670, Pl. VII0 v1151 aStendell, W. uhttps://www.biodiversitylibrary.org/page/975360102502nas a2200145 4500008004100000022001300041245011400054210006900168260001600237520196500253100002202218700002902240700002102269856006602290 2016 eng d a0928425700aObject discrimination through active electrolocation: Shape recognition and the influence of electrical noise0 aObject discrimination through active electrolocation Shape recog cJan-12-20163 a

The weakly electric fish Gnathonemus petersii can recognise objects using active electrolocation. Here, we tested two aspects of object recognition; first whether shape recognition might be influenced by movement of the fish, and second whether object discrimination is affected by the presence of electrical noise from conspecifics. (i) Unlike other object features, such as size or volume, no parameter within a single electrical image has been found that encodes object shape. We investigated whether shape recognition might be facilitated by movement-induced modulations (MIM) of the set of electrical images that are created as a fish swims past an object. Fish were trained to discriminate between pairs of objects that either created similar or dissimilar levels of MIM of the electrical images. As predicted, the fish were able to discriminate between objects up to a longer distance if there was a large difference in MIM between the objects than if there was a small difference. This supports an involvement of MIMs in shape recognition but the use of other cues cannot be excluded. (ii) Electrical noise might impair object recognition if the noise signals overlap with the EODs of an electrolocating fish. To avoid jamming, we predicted that fish might employ pulsing strategies to prevent overlaps. To investigate the influence of electrical noise on discrimination performance, two fish were tested either in the presence of a conspecific or of playback signals and the electric signals were recorded during the experiments. The fish were surprisingly immune to jamming by conspecifics: While the discrimination performance of one fish dropped to chance level when more than 22% of its EODs overlapped with the noise signals, the performance of the other fish was not impaired even when all its EODs overlapped. Neither of the fish changed their pulsing behaviour, suggesting that they did not use any kind of jamming avoidance strategy.

1 aSchumacher, Sarah1 ade Perera, Theresa, Burt1 avon der Emde, G. uhttp://linkinghub.elsevier.com/retrieve/pii/S092842571630030402878nas a2200157 4500008004100000022001400041245008600055210006900141260001600210520234200226100001602568700003102584700001902615700001802634856006802652 2016 eng d a0270-647400aSensory flow as a basis for a novel distance cue in freely behaving electric fish0 aSensory flow as a basis for a novel distance cue in freely behav cNov-24-20163 a

ABSTRACT

The sensory input that an animal receives is directly linked to its motor activity. Behavior thus enables animals to influence their sensory input, a concept referred to as active sensing. How such behavior can serve as a scaffold for generating sensory information is of general scientific interest. In this article, we investigate how behavior can shape sensory information by using some unique features of the sensorimotor system of the weakly electric fish.

Based on quantitative behavioral characterizations and computational reconstruction of sensory input, we show how electrosensory flow is actively created during highly patterned, spontaneous behavior in Gnathonemus petersii. The spatiotemporal structure of the sensory input provides information for the computation of a novel distance cue, which allows for a continuous estimation of distance. This has significant advantages over previously known non-dynamic distance estimators as determined from electric image blur.

Our investigation of the sensorimotor interactions in pulsatile electrolocation show, for the first time, that the electrosensory flow contains behaviorally relevant information only accessible through active behavior. As patterned sensory behaviors are a shared feature of (active) sensory systems, our results have general implications for the understanding of (active) sensing, with the proposed sensory flow based-measure being potentially pertinent to a broad range of sensory modalities.

SIGNIFICANCE STATEMENT

Acquisition of sensory information depends on motion, as either an animal or its sensors move. Behavior can thus actively influence the sensory flow, and in this way, behavior can be seen as a manifestation of the brain's integrative functions. The properties of the active pulsatile electrolocation system in Gnathonemus petersii allow for the sensory input to be computationally reconstructed, enabling us to link the informational content of spatiotemporal sensory dynamics to behavior. Our study reveals a novel sensory cue for estimating depth that is actively generated by the fishes' behavior. The physical and behavioral similarities between electrolocation and other active sensory systems suggest that this may be a mechanism shared by (active) sensory systems.

1 aHofmann, V.1 aSanguinetti-Scheck, J., I.1 aGomez-Sena, L.1 aEngelmann, J. uhttp://www.jneurosci.org/cgi/doi/10.1523/JNEUROSCI.1361-16.201601242nas a2200157 4500008004100000022001400041245009700055210006900152260001600221300001400237490000700251520074400258100001701002700001501019856005001034 2005 eng d a0022-111200aThe anal fin complex in a weakly discharging electric fish, Gnathonemus petersii(Mormyridae)0 aanal fin complex in a weakly discharging electric fish Gnathonem cJan-01-2005 a266 - 2750 v663 a

An examination of the permanent bony structures of the anal fin complex in the mormyrid fish, Gnathonemus petersii, revealed two new structural sexual dimorphisms: longer proximal pterygiophores and wider anal fin rays in males than in females. Both structures are thought to facilitate the male’s courtship-associated anal fin reflex. Adult male mormyrid fishes are characterized by a dorsally directed indentation of the posterior body wall (anal fin indentation). The expression of this indentation in males, presumably driven by anal fin musculature, was correlated with the fish’s gonadal state: large indentations were associated with high gonado-somatic indices and small indentations with low indices.

1 aGreisman, L.1 aMoller, P. uhttp://www.blackwell-synergy.com/toc/jfb/66/101371nas a2200157 4500008004100000022001400041245011500055210006900170260001600239300001400255490000700269520085400276100001801130700001501148856005001163 1998 eng d a0022-111200aA sexually dimorphic basal anal-fin ray expansion in the weakly discharging electric fish Gnathonemus petersii0 asexually dimorphic basal analfin ray expansion in the weakly dis cJan-09-1998 a638 - 6440 v533 a

Male Gnathonemus petersii (Mormyridae) exhibit two structural, sexually dimorphic characters: anal-fin ray bone expansion and an indentation of the posterior ventral body wall (formerly described as anal-fin indentation). Females lack this bone expansion, but may show a slight indentation. Morphometric data on both characters were obtained from radiographs of 414 fish (males and females) ranging in size from 60 to 276 mm Ls. Both body wall indentation and bone expansion began to develop in males of about 120 mm Ls. At 160–180 mm, the sex ratio of fish with expansion to fish without expansion was 50 : 50. Androgens seem to affect the expression of both these sexual dimorphisms. Bone expansion may provide increased bone surface for muscle attachment and thus facilitate the anal-fin reflex during courtship behaviour.

1 aPezzanite, B.1 aMoller, P. uhttp://www.blackwell-synergy.com/toc/jfb/53/300340nas a2200121 4500008004100000245003100041210003100072300000700103490000700110653002200117100003100139856004800170 1862 eng d00aEine neue art von Mormyrus0 aEine neue art von Mormyrus a640 v2810aMormyrus petersii1 aGünther, Albert, C. L. G. uhttp://biodiversitylibrary.org/page/716051600411nas a2200109 4500008004100000245007600041210006900117300001200186490000900198100002600207856006800233 1899 eng d00aA revision of the genera and species of fishes of the family Mormyridae0 arevision of the genera and species of fishes of the family Mormy a775-8210 v18981 aBoulenger, George, A. uhttp://www.biodiversitylibrary.org/item/97095#page/919/mode/1up00460nas a2200121 4500008004100000245009000041210006900131260004500200300001100245490000600256100002600262856005000288 1909 eng d00aCatalogue of the Fresh-Water Fishes of Africa in the British Museum (Natural History)0 aCatalogue of the FreshWater Fishes of Africa in the British Muse aLondonbBritish Museum (Natural History) a29-1450 vI1 aBoulenger, George, A. uhttps://biodiversitylibrary.org/page/3788960900399nas a2200109 4500008004100000245009100041210006900132300001400201490000700215100001800222856004900240 1919 eng d00aPoissons du Gribingui recueillis par M. Baudon. Description de sept espèces nouvelles0 aPoissons du Gribingui recueillis par M Baudon Description de sep a201–2140 v441 aPellegrin, J. uhttp://biodiversitylibrary.org/page/3598078801508nas a2200133 4500008004100000245011100041210006900152260001200221300001400233490000700247520105100254100001701305856005201322 1936 eng d00aZoological results of the George Vanderbilt African Expedition of 1934. Part III,–The fresh water fishes0 aZoological results of the George Vanderbilt African Expedition o c07/1936 a243–3350 v883 a

The Academy is fortunate in securing the very interesting collection obtained by this expedition. Considering the wide range of localities or stations across transcontinental Africa, of which 39 are listed in part 1 of the present series of papers,’ only 7 yielded fishes. These are: (13) Athi River Crossing, (17) Kitala, (23) Saidi’s Village, (24) Vube, (26) Eki- bondo’s Village, (27) Fort Sibut and (33) Nola. Other smaller lots of materials were later received from 30 kilometers east of Kribi, Cameroons, and Batangafo, Chad Basin. The specimens number nearly 3000, representing 115 species, of which 10 are described as new genera or subgenera and 36 as new species or sub- species. This is surely a remarkable showing, especially in view of the comparatively short amount of time available and the mobility of the expedition. To Mr. George Vanderbilt is due special acknowledgment for his per- sonal interest in the collecting of the specimens, and amassing comprehen- sive series for the museum of the Academy.

1 aFowler, H.W. uhttps://mormyrids.efishgenomics.com/fr/node/12500398nas a2200121 4500008004100000245006700041210006600108260001200174300001100186490000700197100002000204856005200224 1928 eng d00aPesci raccolti dal March. Saverio Patrizi nel bacino del Congo0 aPesci raccolti dal March Saverio Patrizi nel bacino del Congo c08/1928 a1–280 v531 aVinciguerra, D. uhttps://mormyrids.efishgenomics.com/fr/node/13300497nas a2200133 4500008004100000245013100041210007000172260001200242300001400254490001600268100001400284700001300298856005200311 1937 eng d00aContribution à la faune ichthyologique du Congo Belge: Collections du Dr. H. Schouteden (1924-1926) et d’autres récolteurs0 aContribution à la faune ichthyologique du Congo Belge Collection c05/1937 a189–2940 v3 (fasc. 5)1 aDavid, L.1 aPoll, M. uhttps://mormyrids.efishgenomics.com/fr/node/12400469nas a2200109 4500008004100000245010700041210006900148260001800217300001200235100001500247856009700262 1964 eng d00aLes poissons du bassin du Tchad et du bassin adjacent du Mayo Kebbi étude systématique et biologique0 aLes poissons du bassin du Tchad et du bassin adjacent du Mayo Ke aParisbORSTOM a1–4831 aBlache, J. uhttp://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_2/memoires/19994.pdf00320nas a2200121 4500008004100000245003300041210003200074260001200106300000900118490000600127100001300133856005200146 1939 eng d00aLes Poissons du Stanley-Pool0 aLes Poissons du StanleyPool c12/1939 a1-600 v41 aPoll, M. uhttps://mormyrids.efishgenomics.com/fr/node/12200416nam a2200121 4500008004100000245005800041210005600099260005500155300000800210653001100218100001300229856005200242 1967 eng d00aContribution à la Faune Ichthyologique de l’Angola0 aContribution à la Faune Ichthyologique de l Angola aLisbonbCompanhia de Diamantes de Angola (DIAMANG) a38110aAngola1 aPoll, M. uhttps://mormyrids.efishgenomics.com/fr/node/10400437nas a2200109 4500008004100000245013100041210006900172300001200241490000700253100001600260856005100276 1990 eng d00aMise en synonymie de Gnathonemus brevicaudatus Pellegrin, 1919 avec Gnathonemus petersii Gunther, 1862 (Teleostei, Mormyridae)0 aMise en synonymie de Gnathonemus brevicaudatus Pellegrin 1919 av a125-1290 v141 aBigorne, R. uhttps://mormyrids.efishgenomics.com/fr/node/7100436nas a2200145 4500008004100000245001500041210001500056260004400071300001200115100001600127700001800143700001400161700001800175856009700193 1990 eng d00aMormyridae0 aMormyridae aParis, Tervuren (Belgium)bORSTOM, MRAC a122-1841 aBigorne, R.1 aLévêque, C.1 aPaugy, D.1 aTeugels, G.G. uhttp://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_6/Fau_trop/34060.pdf00308nas a2200121 4500008004100000245001500041210001500056260001800071300001200089490000600101100001600107856006300123 2003 eng d00aMormyridae0 aMormyridae bIRD/MNHN/MRAC a154-2220 v11 aBigorne, R. uhttp://www.ird.fr/editions/catalogue/ouvrage.php?livre=40900456nam a2200121 4500008004100000022002300041245005600064210004900120260004200169490000900211100001500220856009900235 2000 eng d aHyb: 3-540-14811-600aThe Mormyridae and other Osteoglossomorpha (CD-ROM)0 aMormyridae and other Osteoglossomorpha CDROM aNew YorkbSpringer Verlag, ETI-UNESCO0 v20001 aHarder, W. uhttps://www.amazon.com/Mormyridae-Osteoglossomorpha-Biodiversity-Database-CD-ROM/dp/354014811600507nas a2200193 4500008004100000020002200041245001900063210001800082260000800100300001400108490000600122100002100128700002400149700002200173700002800195700001800223700002100241856005100262 2007 eng d a978-2-7099-1621-900a12. Mormyridae0 a12 Mormyridae bIRD a220–3340 v11 aHopkins, Carl, D1 aLavoué, Sébastien1 aSullivan, John, P1 aStiassny, Melanie, L.J.1 aTeugels, G.G.1 aHopkins, Carl, D uhttps://mormyrids.efishgenomics.com/fr/node/35