Short Communication |
Corresponding author: Eva Hnátková ( hnatkova@tf.czu.cz ) Academic editor: Natalia Golub
© 2023 Eva Hnátková, Zuzana Majtánová, Vendula Bohlen Šlechtová, Joerg Bohlen, Petr Ráb.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Hnátková E, Majtánová Z, Bohlen Šlechtová V, Bohlen J, Ráb P (2023) Karyotype of Sabanejewia bulgarica (Drensky, 1928) (Teleostei, Cobitidae) from the Danube Delta, Romania. Comparative Cytogenetics 17: 157-162. https://doi.org/10.3897/compcytogen.17.103152
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The karyotype of the freshwater fish Sabanejewia bulgarica (Drensky, 1928), from the Danube Delta, was studied by conventional Giemsa staining and the C-banding technique. The diploid chromosome number was 2n = 50. The karyotype contained 2 pairs of metacentric (the first one was much larger than the second one), 6 pairs of submetacentric and 17 pairs of subtelocentric to acrocentric chromosomes. Pericentromeric blocks of heterochromatin were revealed in most of the chromosome pairs. The karyotype phenotype of S. bulgarica was the same as found for S. balcanica from Northern Carpathian Mountains.
C-heterochromatin, Chromosome number, cobitoid loaches, karyotype structure
Freshwater fishes of the genus Sabanejewia Vladykov, 1929 are small (max 15 cm TL), have a benthic lifestyle in river habitats and can be distinguished from all other genera of Cobitidae by a specific sexual dimorphism (males with lateral body swellings) (
Sabanejewia bulgarica
(Drensky, 1928) was originally described as a species of the genus Cobitis Linnaeus, 1758 occurring in the lowest Danube basin including the Danube River itself. Junior synonyms are C. albicoloris Chichkoff, 1932 and C. taenia tesselatus Pietschman, 1937 (
Chromosomes of the loaches of the genus Sabanejewia remain poorly studied.
The five Sabanejewia bulgarica specimens examined (all females) were collected in the Saint George Branch, Danube Delta (July 1997). The loach individuals arrived at the laboratory (Danube Delta Institute, Tulcea) in very bad condition and died subsequently. One female displayed the colour pattern and high body as described in original description by
Standard procedure for chromosome preparation followed
The diploid chromosome number was determined as 2n = 50 in all five individuals. The detailed karyotype analysis was carried out on a single specimen with morphological characters corresponding to the original description (Fig.
Our results enable us to compare the karyotype of Sabanejewia bulgarica with karyotypes of other species of this genus analysed so far (Table
In conclusion, the karyotype of S. bulgarica from the Danube Delta is very similar to karyotypes of other Sabanejewia species in respect of the chromosome number and morphological types of chromosomes, and is nearly identical with karyotype of S. balcanica from the Northern Carpathian range in Slovakia. Further detailed cytotaxonomic as well as other genetic surveys of populations of Sabanejewia throughout its distribution will answer problems of systematics of Danubian golden loaches.
Analysed females of Sabanejewia bulgarica from the Saint George Branch, Danube Delta A individual with colour pattern and high body as described in original description by
Karyotype of female Sabanejewia bulgarica arranged from conventionally Giemsa-stained (the first row) and sequentially C-banded (the second row, large blocks denoted by arrows) chromosomes. m – metacentric, sm – submetacentric, st – subtelocentric and a – acrocentric chromosomes.
Diploid chromosome numbers (2n) and karyotype structure of karyologically studied species of genus Sabanejewia. Types of chromosomes: m –metacentric, sm – submetacentric, st – subtelocentric, a – acrocentric.
Species | 2n | Karyotype characteristics | References | |||
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m | sm | st | a | |||
S. larvata | 50 | 2 | 3 | 11 | 9 |
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S. caspia | 50 | 2 | 3 | 11 | 9 |
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S. kubanica | 50 | 3 | 7 | 15 |
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S. aurata aurata | 50 | 3 | 6 | 16 |
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S. (aurata) balcanica | 50 | 2 | 6 | 17 |
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S. (aurata) balcanica | 50 | 2 | 6 | 17 |
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S. baltica | 50 | 2 | 8 | 15 |
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S. bulgarica | 50 | 2 | 6 | 17 | This study |
We thank to late T. T. Nalbant, Department of Taxonomy and Evolution, Institute of Biology, Bucharest, Romania, for determination of the loaches in this study and to Cristina Ene, Danube Delta Research Institute, for collection and providing the material for this study. This study was supported by project EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE and RVO: 67985904 (E. H., Z. M., V. B. Š., J. B., P. R.).
Eva Hnátková https://orcid.org/0000-0002-0892-9557