@article {614, title = {Derived karyotypes in two elephantfish genera (Hyperopisus and Pollimyrus): lowest chromosome number in the family Mormyridae (Osteoglossiformes)}, volume = {15}, year = {2021}, month = {Oct-08-2021}, pages = {345-354}, abstract = {

The African weakly electric elephantfish family Mormyridae comprises 22 genera and almost 230 species. Up-to-date cytogenetic information was available for 17 species representing 14 genera. Here we report chromosome number and morphology in Hyperopisus bebe (Lacep\ède, 1803) and Pollimyrus isidori (Valenciennes, 1847) collected from the White Nile system in southwestern Ethiopia. Both taxa displayed the diploid chromosome number 2n = 40, but they differed in fundamental numbers: FN = 66 in H. bebe and FN = 72 in P. isidori; previously the same diploid chromosome number 2n = 40 was reported in an undescribed species of Pollimyrus Taverne, 1971 (FN = 42) from the same region. Our results demonstrate that not only pericentric inversions, but fusions also played a substantial role in the evolution of the mormyrid karyotype structure. If the hypothesis that the karyotype structure with 2n = 50\–52 and prevalence of the uni-armed chromosomes close to the ancestral condition for the family Mormyridae is correct, the most derived karyotype structures are found in the Mormyrus Linnaeus, 1758 species with 2n = 50 and the highest number of bi-armed elements in their compliments compared to all other mormyrids and in Pollimyrus isidori with the highest number of bi-armed elements among the mormyrids with 2n = 40.

}, issn = {1993-078X, 1993-0771}, doi = {10.3897/compcytogen.v15.i4.67681}, url = {http://dx.doi.org/10.3897/compcytogen.v15.i4.67681}, author = {Simanovsky, Sergey and Medvedev, Dmitry and Tefera, Fekadu and Alexander Golubtsov} } @article {613, title = {First cytogenetic information for five Nilotic elephantfishes and a problem of ancestral karyotype of the family Mormyridae (Osteoglossiformes)}, volume = {14}, year = {2020}, month = {Aug-19-2020}, pages = {387-397}, abstract = {

The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (G\ünther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

}, issn = {1993-078X, 1993-0771}, doi = {10.3897/compcytogen.14i3.52727}, url = {http://dx.doi.org/10.3897/compcytogen.14i3.52727}, author = {Simanovsky, Sergey and Medvedev, Dmitry and Tefera, Fekadu and Alexander Golubtsov} } @article {561, title = {Electric Organ Discharges of Cyphomyrus petherici (Mormyridae, Osteoglossiformes) from the White Nile Basin}, journal = {Doklady Biological Sciences}, volume = {481}, year = {2018}, month = {Jan-07-2018}, pages = {142 - 145}, abstract = {

The waveform and some characteristics of the electric organ discharges have been studied in 11 individuals of Cyphomyrus petherici, the only representative of the genus in the Nilotic fauna. The discharge is characterized by three to five phases with a prevalence of the second phase in terms of the relative amplitude and a wide variability of the total duration of discharge (from 212 to 558 \μs). The comparison of the discharges of the species under study with those in the congeneric species and representatives of the genus Pollimyrus (which previously encompassed C. petherici) demonstrates a general similarity of the C. petherici discharges with those of Cyphomyrus, but not Pollimyrus. This is in agreement with the correspondence of the discharge characteristics observed in other mormyrids to the phylogenetic position and taxonomic status of the species.

}, issn = {0012-4966}, doi = {10.1134/S0012496618040038}, url = {http://link.springer.com/10.1134/S0012496618040038}, author = {Baron, V. D. and Orlov, A. A. and Alexander Golubtsov} } @article {547, title = {New insights into the molecular phylogeny and taxonomy of mormyrids (Osteoglossiformes, Actinopterygii) in northern East Africa}, journal = {Journal of Zoological Systematics and Evolutionary Research}, year = {2017}, month = {Feb-09-2019}, abstract = {

Based on morphological data and analysis of mitochondrial cytochrome b gene and nuclear (S7 intron 1) DNA sequences, the phylogenetic relationships of all Pollimyrus species known from the Omo-Turkana enclosed basin and Nile system below the Murchison Falls were solved. A mormyrid \“Pollimyrus\” petherici is distantly related to all other studied Pollimyrus species and clusters together with Cyphomyrus species forming with the later a monophyletic group. Moreover, the West African (but not the Congo River) populations of Cyphomyrus psittacus, the type species of the genus, seem to be conspecific to C. petherici. That is, the range of the genus Cyphomyrus is extended toward the Nile and Omo-Turkana basins. This genus belongs to the large clade widely distributed in sub-Saharian Africa and characterized by the presence of a chin appendage. Significance of this character for mormyrid phylogeny is discussed. Two distinct lineages of Pollimyrus occurring sympatrically in the White Nile tributaries and previously reported as the light and dark forms of Pollimyrus isidori together with five other congeneric species studied form a monophyletic group. The light form apparently represents P. isidori distributed in the Nile system downstream of the Murchison Falls and West Africa; the dark-colored form (designated as Pollimyrus \“D\”) represents a distinct phylogenetic lineage inhabiting both the Omo-Turkana and the White Nile basin. Morphological and ecological data suggest that this form may be conspecific to East African Pollimyrus nigricans or most probably represents a new species.

}, doi = {10.1111/jzs.12186}, url = {http://doi.wiley.com/10.1111/jzs.12186}, author = {Levin, Boris A. and Alexander Golubtsov} } @article {898, title = {Variation of electric organ discharge in Mormyrus kannume (Mormyridae) from south-western Ethiopia in relation to individual size, sex and reproductive status}, journal = {Journal of Ichthyology}, volume = {54}, year = {2014}, month = {3/2014}, pages = {177 - 185}, abstract = {

Five variables of the electric organ discharge (EOD) were studied in 132 freshly caught individuals of Mormyrus kannume from the Gibe and Gojeb rivers (the enclosed Omo-Turkana system) and Baro River (the White Nile system) in south-western Ethiopia, East Africa. Most individuals exhibited the typical biphasic EODs with an initial head-positive phase followed by a head-negative phase exceeding initial one in the relative amplitude. In three repeated samples from the Gibe, stable differences in the discharge variables between females and males were found, while no sex differences were observed in other samples. In three cases, a positive correlation between the individual size and discharge duration was found: in two male subsamples from the Gibe and in a mixed sample of both sexes from the Gojeb. In most samples studied, some males exhibited the outstandingly long EOD duration. At the same time, no relationships between the discharge variables and reproductive status of individuals were found. The possible influence of individual and intra-individual variations on the results of inter-population and interspecific comparisons of the discharge variables in mormyrids are highlighted.

}, issn = {1555-6425}, doi = {10.1134/S0032945214020039}, url = {http://link.springer.com/10.1134/S0032945214020039http://link.springer.com/content/pdf/10.1134/S0032945214020039}, author = {Alexander Golubtsov and Orlov, A. A.} }